Weak current College】 【valve electric device selection method.

Because electric valve is a valve and actuator combination, so when the valve is to determine how to properly select, after the electronic device is related to the actual use of the ability to meet project needs. When you select electric device not only consider the foregoing work environment, electrical control and general technical performance, but also for electric appliance integrated technology performance should be fully taken into account.

1. electric device output torque and speed

Output torque value is the electric device of one of the important technical parameters, and also the use will need to select the important parameters. If you assembled electric valve selection of electric appliance when output torque is too large or less are not desirable. Because of General Electric appliance factory in the factory are required output torque value of testing and adjustment, is relatively accurate. If you choose to use very large output torque margin will make electric valve has a great potential danger in the event of failure to control protection will easily cause damage to the valve (valve stem, valve rupture) phenomenon, it is easy to result pipeline system. So the output torque margin choose too large is not desirable. If you are in practice not open valves belong to select is not reasonable.

On the electric device output speed determines, at the time of its opening and closing the valve is not strictly required, you should try to choose a slow speed.

Because unnecessary more speed, in the same torque demand will increase the motor power, this will not only a waste of energy, increasing construction costs, but also makes the electric device volume increase which resulted in many aspects of the waste.

Currently the self-developed electric appliance, in each frame size in design with the motor specification number (generally 2-3), as well as the main driving gears and worm changes the range of speed ratio is limited, so each frame size of torque tranche and speed are not numerous. tranche

2, electric appliance maximum thrust value allowed

If the valve axial force commitment by electric appliance (stem nut in electric appliance), its thrust values do not allow more than the allowed values for electric installations.

3. the valve stem nut of the number of maximum circling

In the selection of multi-turn valve electric device must indicate when the valve stem nut of the number of maximum spinning around, so you can correctly matching electric device position indication in the institution of the gear ratio, so that location indicates sufficient precision meets valve work on the valve to open and close degree of observation, easy impression, affecting its normal work.

4, the valve stem diameter of allowed values

Lifting the valve selection electric device should be aware of its allowed values through the valve stem diameter, the diameter of the stem must be less than the value. Additionally, for multi-turn electric actuator, the selection should also cover the stem height requirements (and the valve diameter for pain). Rotary valve is equipped with the valve cover.

5, valve and actuator connection

Valve and actuator connection type and size should be consistent with the national standard: GB/T12222-1989 multi-turn valve drive connections, GB/T12223-1989 part of rotary valves driven devices connection.

Currently, the part of the rotary valve electric device with mechanical limit to prevent cannot determine disc location, such valves and electric appliances connect screw and keyway position correspond to the requirements strictly.

【 Weak current College 】 decoration must know knowledge of PPR pipes

All new home decoration, especially in the water this piece, you will use to PPR pipe, now available in the brand so many, but you have learned how to distinguish the quality is good or bad? if you used the wrong product, home to become a flood plain, then not only expensive, but also the mood. You should understand some knowledge of PPR. These are necessarily need to know about:
1, PPR stuff.

PPR's chemical name for copolymer, as can be seen in its material form the polypropylene copolymer for gas, technology, it is a synthetic chemical materials. Market, the best raw material supply from PPR, Europe's no. 2 provider is Korea, China is no good-quality raw materials suppliers of PPR. Therefore, select the PPR pipe, then ask your PPR raw materials are from? due to cost factors, and indeed manufacturers select the raw material, but Korea unscrupulous manufacturers you will select the recovery of waste reprocessing. So, see the color you'll know about it.

2, the difference between hot and cold water pipes PPR.

Hot and cold water pipes of different wall thickness, can bear pressure, cold water pipe is 16 kg, hot water pipe is 20 kg. The thermal conductivity, they are not the same, cold water and hot water pipes can pass, cold water pipes should not pass the hot water. There are hot and cold pipes, mainly because of the cold water pipes require less, so can offer lower prices. If economic conditions permitting, all purchased using hot water pipe is the best strategy.

3 some of the features of the PPR.

A, health. Material exclusively by carbon, hydrogen, it is not added to any toxic heavy metal salt additives.

B, heat resistance, good insulation properties. Maximum use temperature up to 95 ° c, transient temperature up to 110 ° c, the long-term working temperature of 70 ° c, could be used as a hot water supply system of pipes, pipe thermal conductivity coefficient of only 1% of the second, has good insulation properties. PPR pipe in the rated temperature and pressure, long service life up to 50 years. PPR pipes, pipes for 50 years, and is achievable.

C, pipe connections. As a result of pipe, pipe fittings are made of uniform raw material processing, integrated hot-melt connection tubing, fittings, connecting parts accessories and pipe melt into a solid overall, the intensity is greater than the strength of the pipe itself, permanently eliminate water leakage risks.

D, green environmentally friendly, recyclable. Production, construction, used in the process without any pollution to the environment, and will not cause pollution. Production and construction waste to recycling, or you can directly use the reproduction of pipes and fittings. However, due to the inevitable dependence has not waste solid impurities, it can produce things color is certainly not pure.

4, correct identification of PPR pipe pros and cons of the method.

A look at PPR pipes: high quality soft colour and texture of oil, poor quality water mixed with the PPR due to poor quality plastic even lime powder, its colour is not natural, cut section dry oil free texture, so I feel like joining the chalk.

2 touch the PPR pipes: high quality both inside and outside wall smooth, no bump crack, inferior PPR pipe inner wall rough sense of a bump.

Three OK: PPR pipes using hand quality fixed weigh weight than inferior PPR pipes to PPR pipes, inferior than high-quality light some, due to the high quality of most metal fittings for PPR with three or more waterproof leakage grooves of copper (CU content greater than 50 per cent), the longer the copper parts dimensions, thickness also thicker, so-to-weight ratio inferior PPR pipes to some.

4 burning: high-quality raw materials of PPR is a hydrocarbon chain compounds, flame temperature higher than 800 ° c above, the ideal combustion case and sufficient oxygen conditions, Burns, only carbon dioxide and water vapour release, burning should be no smell and residue, but the poor quality of PPR pipes due to mixing with inferior plastics and other impurities, combustion will smell and residue. From PPR pipe cut thin slices with a lighter combustion to identification.

Don't forget-quality, it is actually more important than the pipe, so choose the accepted norms of brand-name products.

【 Weak current College 】 pipe standards introduced in common terminology

1) a generic term

① delivery status
Refers to the final delivery of the products of plastic deformation or the status of the final heat treatment. General delivery without heat treatment called hot-rolled or cold-drawing (rolling) State or manufacturing status; after heat treatment delivery of that State, or heat treatment under the heat of the category called normalizing (often), hardening and tempering, annealing, solid state. When ordering, order status indicated in the contract.

② by actual weight of the delivery or delivery by theoretical weight
Actual weight--the time of delivery, the product weight is the weight (and weighed) weight of delivery;
Theoretical weight--the time of delivery, the product weight is based on steel nominal size calculated by weight. The calculation formula is as follows (the weight of the delivery requirements according to the theory, indicate in the contract):
Pipe weight per metre of theory (steel density 7.85kg/dm3) calculation formula:
W=0.02466（D-S）S
Type: W--theoretical weight per m of steel pipe, kg/m;
D--pipe nominal outer diameter, mm;
S-pipe nominal wall thickness, mm.

③ guarantee conditions
Under current standards projects for inspection and ensure that they meet standard requirements, called guarantee conditions. Guarantee conditions are divided into:
A basic guarantee conditions, (also known as will guarantee conditions). Whether a customer is indicated in the contract. Shall be carried out according to the standards and to ensure that the test results meet standard requirements.
Such as chemical composition, mechanical properties, dimensional deviation, surface quality and testing, pressure experiment or flattening or flaring, process performance experiments are required insurance conditions.
B, agreements guarantee conditions: standard in addition to basic guarantee conditions, there are "according to the demand-side requirements, after consulting both supply and demand, and listed in the contract? quot; or when the demand-side requirements ... Should be indicated in the contract "; and the customer, on the basic guarantees in standard conditions with strict requirements (such as composition, mechanical properties, dimensional deviations, etc.) or an inspection item (such as the wall thickness of steel pipe ellipticity, does not equal). The above terms and requirements, in order, from both supply and demand, supply technical agreement signed and dated in the contract. Therefore, these conditions also known as Protocol guarantee conditions. There was agreement that the condition of the product, generally to the price increase.

④ batch
Standard in the "batch" means an inspection unit, i.e. the inspection lot. If the delivery unit unit, called delivery batches. When bulk delivery, a delivery group may include several inspection lot; when the delivery volume when an inspection lot can be divided into several batches of delivery.

The composition of "instalment" typically have the following requirements (see the related standards):
A, each batch shall be composed of the same grade (grade), same furnace (cans), or the same oven number, same size and same heat treatment system (furnace) of steel.
B, for high-quality carbon steel structure, fluid, can different furnace (pot) of the same brand, same size and same heat treatment system (furnace) of steel.
C, welded steel tubes each batch shall be composed of the same grade (grade), composed of the same specification of pipe.

⑤ high-quality steel and high-quality steel
In GB/T699-1999 and GB/T3077-1999 standards, its trademark followed by the word "A", as the high-quality steel, contrary to the generally high-quality steel.
High-quality steel in some or all of the following is greater than that of high-quality steel:
A range of element content, reduced;
B, reduce harmful elements (such as sulfur, phosphorus, copper) content;
C, guarantee a high purity (requires fewer non-metallic inclusion content);
D, guarantee a high mechanical and technological properties.

⑥ vertical and horizontal
Standard in longitudinal direction is parallel processing (that is, with processing direction); transverse denotes processing direction vertical (processing direction i.e. steel pipe axial).
Do impact energy experiment, vertical specimen orientation because of fracture and processing. Therefore calls the horizontal fracture; horizontal specimen fracture due to processing and parallel to the direction, therefore calls longitudinal fracture.

(2) steel pipe shapes, size terminology

① the nominal size and the actual size
A, nominal size: is the standard provisions is nominal, is users and enterprises looking for the ideal size is indicated in the contract size of order.
B, actual size: is the production process in actual size, this size is often greater than or less than the nominal size. This is greater than or less than the nominal dimensions of the phenomenon known as the deviation.

② deviation and tolerances
A, deviation: in the production process, because the actual size can be difficult to achieve nominal size requirements, that is often greater than or less than the nominal size, so the standard establishes the actual size and nominal size there is a difference between allowed. The difference is positive, called positive difference is negative the negative deviation of calls.
B, tolerance: standards of a plus or minus the sum of the absolute deviation value is called tolerance, also called "tolerance zone".
Deviation is directional, which means to "positive" or "negative" said; the tolerance is not directional, therefore, the deviation values are known as "tolerance" or "bear tolerance" is the wrong term.

③ delivery length
Delivery length also known as user requirements for length or contract length. The standard length for delivery in the following provisions:
A, usually length (also known as the non-fixed length length): where length is the length of the standard provisions within and no fixed length requirements, are known as usual length. For example, structural pipe standards: hot (squeeze. expansion) steel pipe 3000mm ~ 12000mm; drawing (rolling) steel pipe 2000mmm ~ 10500mm.

B, lengthLength: length length length should be generally, is within the scope of the contract in a fixed-length dimensions. But the actual operation are cut absolute length length is unlikely, therefore, standard provisions for length length allowed is deviation value.
Structural tube standard is:
Production length length length of tube than usual tubes yield drop large production companies fare request is reasonable. Increase the enterprise is not entirely consistent, usually on the basis of a benchmark price increase of 10%.

C, double length length: double length length length should be generally, the contract should specify single foot length and total length in multiples of the Constitution (e.g. 3000mm× 3 multiples of 3 3000mm, total length to 9000mm). Actual operation, should be based on the total length plus allows positive 20mm, plus every single foot length should be kept cut cushion. Structural tube, for example, provisions remain cut cushion: outside diameter ≤ 5 ~ 10mm 159mm; outer diameter > 10 ~ 15mm 159mm.
If the standard deviation of non-double length length and cutting margin requirement should be determined by supply and demand sides, consultations and indicate in the contract. Times the length scales with fixed length length, will give the production enterprise yield significantly reduced, thus producing enterprise is reasonable fare, the fare increases with the length length increases in basically the same.

D, scope length: the length of the range in the ordinary length, when a user requests a fixed length of the range, in the contract notice.
For example: typically has alength of 3000 ~ 12000mm and scope length length 6000 ~ 8000mm or 8000 ~ 10000mm.
Visible range is longer than length and generous double length length requirement, but the length of the stringent than usual, also production enterprises to bring yield reduction. Therefore manufacturers fare is justified, the increase in the basic prices increase on average 4%.

④ wall thickness are not
Pipe wall thickness is not possible throughout the same, in the cross-section and longitudinal tube wall thickness is not on the objective existence, namely the phenomena such as uneven thickness. In order to control this heterogeneity in some pipe standards set forth in the wall thickness is not allowed to index, as a general rule not exceed 80% of the wall thickness tolerances (after consultation with both supply and demand).

⑤ ellipticity
In circular pipe cross-section on the outer diameter of phenomena, that is, there are not necessarily mutually perpendicular maximum outer diameter and minimum outside diameters, the maximum outer diameter and the difference between the minimum diameter is oval degrees (or out-of-roundness). In order to control the ellipticity, steel pipe standards provides the oval of the General provisions allowing indicators, not more than 80% tolerance for the outside diameter (after consultation with both supply and demand).

⑥ bending
The length of the tube in a curve, on a number of its degree of curvature curve is called. Standard in bending is generally divided into the following two ways:
Local curvature: A, a metre long ruler by amount in the maximum bending of steel tubes, measuring its chord height (mm), which is the local curvature, numeric value with a unit for mm/m, represents a method such as 2.5mm/m. This method also applies to pipe ends are curvature.
B, full-length total curvature with a piece of string, from both ends of the tube, measuring pipe tensile bending Department Max chord height (mm), and then converting development degree (in m), a percentage of the length of the tube length bending.
For example: pipe length 8m, measured maximum chord height 30mm, the tube length bending should be:
0.03÷8m×100%=0.375%

⑦ oversize
Oversize or dimensions exceed the standards of tolerance. Here's the "size" mainly refers to the outer diameter and wall thickness of steel tubes. Usually someone put oversize habit called "tolerance in line", to equate deviation and tolerance is not known, you should call close "/" deviation. Here's deviation might be "positive" or "negative", rarely in the same batch of steel pipe in the positive and negative deviations are off-color ".

(3) chemical analysis terms

Chemical composition of steel is the relationship between the steel quality and end-use performance of one of the important factors, and also the preparation of steel products, as well as the final product is based mainly on heat treatment system. Therefore, the technical requirements of steel standards, often first establishes the applicable grade steel products (steel grade) and chemical composition, and the inclusion of standards in tabular form, is a production enterprise and customer acceptance of steel and steel products important constituents.

① steel melting components
General standards in chemical composition is the melting components. It is the steel smelting is complete, the chemical composition of the casting of the medium-term. To have a certain representation, that is, on behalf of the furnace or cans of average composition, sampling standard methods, the liquid steel into the sample mold, small ingots on a plane or drill sampling, in accordance with the provisions of the standard (GB/T223) for analysis, the results must conform to the standard range of constituents, and is also the basis of customer acceptance.

② finished components
The finished component called validation and analysis components, from the provisions on thefinished steel products (GB/T222) drillthrough or scrap of planing sampling, and in accordance with the provisions of the standard (GB/T223) for analysis of chemical composition. Steel in mold and plastic deformation, later because steel alloying elements in the uneven distribution of (segregation), thus allowing the finished product composition and scope of standard components (melting) discrepancies between the deviation value shall conform to GB/T222.

Steel production components mainly for the use or acceptance of the quality inspection departments using steel quality, production enterprises generally not do analysis of finished product (except as required by the user), but should ensure that finished products meet the standard requirements of.

③ the arbitral analysis
Because both laboratory analysis of the sameThe result of a significant difference and beyond two laboratories allow analysis of error, or a production company and sector, demand-side and supply-side on the same sample or the same analysis of finished steel products have differences, can be used by third-party analysis with rich experience of authority (such as the Chinese iron and Steel Institute or a commodity inspection eligible Inspection Department) for further analysis, namely that of the arbitral analysis. The results of the analysis of arbitration shall be final judgment.

(4), mechanical properties of terminology
Mechanical performance of steel products is to ensure that the final performance of steel (mechanical properties) of key indicators, it depends on the chemical composition of steel and its heat treatment system. In steel standards, according to the different usage requirements, establishes the tensile properties (tensile strength, yield strength and yield point, elongation) as well as hardness, toughness and indicators, as well as user requirements of high and low temperature performance, etc.

① tensile strength (σ b)
Specimens in the drawing process, pull off when the most vigorously (Fb), out to sample the cross-sectional area (So) from stress (σ), known as the tensile strength (σ b), N/mm2 (MPa). It represents the metal materials in the tension field resistance capacity of maximum. Formula:
Type: Fb--specimen pull off, when the most vigorously, N (n);
So--the original sample, mm2 cross-section.

② yield point (σ s)
With yield phenomenon of metal materials, sample drawing procedure in force does not increase (constant) is still able to elongate the stress that when the yield point. To force a drop occurs, you should distinguish between upper and lower yield point. Yield point in N/mm2 (MPa).
Upper yield point (σ s u): specimen yield and force first decline before the maximum stress;
The yield point (σ s l): when excluding the initial transient effects, yield the minimum of stress.
Yield point calculation formula is:
Type: Fs--sample drawing procedure yield strength (constant), N (n);
So--the original sample, mm2 cross-section.

③ fractured elongation (σ)
In the tensile test, the test sample after its scale distance, the length and the percentage of the gauge length, known as elongation. To σ represents, in%. Formula:
Type: L1-sample scale distance of la break length, mm;
L0--sample the original scale distance length, mm.

④ section shrinkage (ψ)
In the tensile test, after its sample la necking at maximum cross sectional cut amount and percentage of the original cross-sectional area, known as section shrinkage. Expressed in units of ψ. Calculated as follows:
Type: S0--sample raw cross-sectional, mm2;
S1--sample la after reducing the minimum cross-sectional, mm2.

⑤ hardness indicators
Metal material resistance hard objects the ability to pressure, surface, called the hardness. According to the test method and the scope of application, the hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, shore hardness and microhardness and high hardness. For tubes commonly have Brinell, Rockwell, Vickers hardness.

A, Brinell hardness (HB)
With a diameter of steel balls or carbide ball to the test force (F) onto the design surface, the provisions of the time after the removal of the test, the measurement of the surface of the specimen creasing diameter (L). Brinell hardness values is to test force divided by the indentation of a spherical surface area. To HBS (ball), N/mm2 (MPa).
The calculation formula is:
Type: F--into the metal surface of the test specimen, N;
D--testing steel ball diameter, mm;
D--the average diameter, mm for indentation.
Determination of Brinell hardness more accurate and reliable, but generally only applies to HBS 450N/mm2 (MPa) of metal materials, hard steel or a thin sheet does not apply. Standard in steel tube, the most widely used Brinell hardness, often to indentation to indicate that the diameter d hardness of the material that is both intuitive and convenient.

For example: 120HBS10/1000130: diameter 10mm steel ball in 1000Kgf (9.807KN) test force, keeping the 30s (seconds) measured Brinell hardness value 120N/mm2 (MPa).

B, Rockwell hardness (HK)
Rockwell hardness testing with Brinell hardness test, is indentation test methods. The difference is that it is measuring the depth of the indentation. That is, in preliminary Yong test force (Fo) and total test force (F) the role of the head (magic factory cone or ball) into the specimen surface, the provisions of the time, remove the main test, a measurement of the residual indentation depth increments (e) calculate the hardness values. Its value is a number without a symbol HR said that the ruler has A, B, C, D, E, F, G, H, K, and so on nine of the ruler. Which are commonly used in the steel hardness test is generally A ruler, B, C, HRA, HRB, HRC.

Hardness value calculated using the following formula:
When using A and C ruler test, HR = 100-e
When to useB ruler test, HR = 130-e
-E--residual indentation depth increment its assorted lines to provide unit 0.002mm said, that is, when the pressure head axial displacement of one unit (0.002mm), i.e. the equivalent of a number of Rockwell hardness changes. E value, the greater the hardness of the metal becomes low, while the higher hardness.
Scope of application of the above three rulers are as follows:
HRA (diamond cone pressure head) 20-88
HRC(Diamond cone pressure head) 20-70
HRB (diameter 1.588mm steel ball Indenter) 20-100

Rockwell hardness test is currently applied to a wide range of methods, including HRC in the use of steel pipe standards after Brinell hardness HB. Rockwell hardness can be applied to measuring the very soft to very hard metal materials, it makes up for Brinell method is not a simple compared to Brinell method, you can directly from the hardness machine dial readout hardness values. However, because of its small indentation, the hardness value less accurate Brinell method.

C, Vickers hardness (HV)

Vickers hardness test is also an indentation test method is a relative angle to 1360 of surface is pyramid of Diamond Head to the selected test force (F) onto the test surface, the provisions of the time after the removal of the test, measuring the length of two diagonal line indentation.

Vickers hardness value is test force divided by the surface area of the indentation, the calculation formula is:
Type: Vickers hardness HV--N/mm2, (MPa);
F-test force, N;
D--indentation the arithmetic mean of the two diagonals, mm.
Vickers hardness test force F used as 5 (49.03), 10 (98.07), 20 (196.1), 30 (294.2), 50 (490.3), 100 (980.7) Kgf (N), six levels, can measure hardness values in the range 5-1000HV.

Represents the method, for example: 640HV30/20 indicates 30Hgf (294.2N) test keep the 20S (seconds) for determination of Vickers hardness value 640N/mm2 (MPa).
Vickers hardness method can be used fordetermination of very thin metal materials and surface hardness. It has the Brinell, Rockwell method of the main advantages, while overcoming their weaknesses of basic, but not as convenient for Rockwell method. Vickers in pipe standards are rarely used.

⑥ impact strength indicators
Impact strength is reflected in the metal come oh external shocks load resistance, general impact toughness values (ak) and impact energy (Ak) indicated that their units are the J/cm2 and J (JOULE).

Impact toughness or impact energy test (hereinafter referred to as "impact test"), is divided into different test temperature and room temperature, low temperature and high-temperature impact test three; if the specimen notch shape can be divided into "V"-shaped gap and "U"-shaped notch impact test.

Impact test with a certain size and shape (10 × 10 × 55mm) specimen (the length of the Middle Office is "U" or "V"-shaped gap, the gap depth 2mm) on the test machine against shock loading under gap broken experiment.
A, shock absorption power Akv (u)--has a certain size and shape of the metal style, under the effect of the impact load absorbed by the break time. Unit is the joule (J) or Kgf.m.
B, impact toughness values akv (u)-shock absorbing work divided by sample gap at the bottom of the cross-sectional area. Unit is the Joule/cm2 (J/cm2) or kilogram force-m/cm 2 (Kgf.m/cm2). Formula:
Type: Akv (u)--specimen broken when the absorption of reactive power, Kgf.m (J);
S--sample gap at the bottom of the cross sectional area office, cm2.

Room temperature impact test temperature of 20 ± 50C; low-temperature impact test temperature range < 15 ~-1920C; high-temperature impact test temperature range of 35 ~ 10000C.

Low-temperature impact test the cooling medium is non-toxic, security, non-corrosive metal and not at the test temperature of solidification of liquid or gas. If ethanol (alcohol), carbon dioxide, solid (dry ice) or liquid nitrogen fog gas (liquid nitrogen).

【 Weak current College 】 small central air-conditioning installation problems---Power By 【 China power house network 】

In recent years, with economic development, the improvement of living standards, being a luxury apartments, small office buildings, villas, House, Penthouse, small size (about a few hundred square meters or so) demanding architectural type. Air conditioning industry urgently needs a product, to the advantage of both together. Some companies see this market, launched the small central air conditioning system. The system has inherited the central air conditioning system with good results and flexible arrangement of household air conditioners and highly intelligent features. From the cost, the small central air than traditional air conditioning cheap 30%-50%. Currently on the market of small central air-conditioning mainly has following several: a, household gas-fired air conditioning air-conditioning started in the 1930s in Sweden, it uses the low grade of gas to energy, energy-saving effect is remarkable. Over the past 10 years, due to the growing problem of energy, power shortages, United States, Switzerland, Germany, Japan's air conditioning industry has developed a number of excellent energy-saving effect is very significant conditioner. Common conditioner has three forms: lithium bromide absorption, ammonia absorption and gas heat pump. Currently on the market to lithium bromide absorption gas air conditioning, usually by means of gas-fired air conditioning LIBR absorption of ammonia gas-fired air conditioning system, air conditioning and gas gas heat pump applications. As China's energy structure changes, natural gas in total energy consumption in proportion to the growing use of air conditioning can simultaneously address consumption in summer too small and too concentrated power, the problem of insufficient power supply. Achieve reductions of peak power, energy balance. With gas prices much lower than the price of gas from the implementation of the strategy, the development of gas-fired air conditioning and bright future. Need to make is that the gas-fired air conditioning refrigeration cycle low thermal coefficient, some constraints on their development. On this issue, to be further development and research. Second, air source heat pump air heat pump is the main form of conditioning, in room rooms, penthouse floor structure, small villas in the broader application, its forms are the three major: (1), type of household air-source heat pump, central air conditioning blowers group produce thermal (cold) wind, like road into the room, compared to other household air conditioning system, which means less investment, and the introduction of fresh air, can realize the indoor and outdoor air circulation, no difference in each room, you can improve the indoor air of ecological housing environment and thermal environment of effective technical means, but building storey need meet wind pipe layout requirements. (2), air-cooled heat pump, Central produce thermal (cold) water, to the air conditioning terminal devices (such as fan coil units, air supply unit, etc.) in the way convenient control and Terminal number matching flexible, construction area of relatively large occasions also applies. But the presence of condensation water discharges and water leakage problems, cost relative to the other two air-source heat pump system is relatively high. (3), the central air conditioner VRV frequency, that is, the current market often referred to as "a few" air conditioning. It is a fluorine, en direct cooling and heating with heat pumps and air conditioning, a desk with several indoor and outdoor unit, each room separately control. Its advantage is that the system is simple, and there is no architectural layers high. Its disadvantage is not easy to leak detection, refrigerant volume decrease occurs, but find no fault in leak location, you can only rely on the continuous supply of refrigerant to maintain the normal operation of the air-conditioning system. 3, water source heat pump water source heat pump is in fact used for the whole building or large living area, etc. Here, we do it is because the air conditioning system to host distributed to each of the air-conditioned area, making it possible to reach extension adjustable, not one or two of use and to start the whole system, resulting in a waste of energy, and a separate kWh meter with users connected burden on the user's own cost. Water source heat pump system mainly two kinds of system: closed-loop water source heat water air conditioning system (central heat stations dispersed all household water source heat pump unit) and the central water-source heat pump hot water system (large water-source heat pump chiller plus indoor air blower plate Tube). Water source heat pump system is electric powered, water as a source of cold (heat). Compared with the air-source heat pumps, high performance coefficient, and is not affected by the outdoor temperature, more suitable for the northern region. The disadvantage is the high initial investment. Currently on the market than the applicable water source heat pump system is a closed loop water water-source heat pump system, it is a double tube closed water systems, parallel connection residential buildings located in each household's water source heat pump unit, summer end unit with circulating water to cool, winter away from heat circulating water. Indoor air flows through the turbine room side of the heat exchanger (summer-winter-evaporator, condenser), like tube system into the main room with air conditioning and heating. The system is installed in a room thermostat for unit commitment and adjust the room temperature, and a separate measurement. Closed water loop without insulation, all lines are almost all in the building, and the circulating water temperature is moderate, not in the pipe surface condensation or substantial loss of heat. 4. heat pump systems utilize the regenerative properties of the soil, advantage buried in the soil of heat pipes for heating and heat exchange, winter, cooling in summer. Its characteristics are placed at will, does not occupy the surface of the external space, take full advantage of the natural low grade heat, energy saving and environmental protection. Its disadvantage is involved hydrogeologic, shall collaborate; higher initial investment system; can cause soil heat to the building as both have a certain influence. The system currently used in small villas. On the small central air-conditioning installation, there is no dedicated standard, mainly with reference to the large central air conditioning and air conditioner installed the corresponding specification. The wind pipes, water pipes can reference a large central air conditioning refrigerant piping is installed, you can reference the household air-conditioning installation; indoor air layout reference large central air conditioner, while outdoor machines installed then you can reference the household air-conditioning installation. In addition, in the small central air conditioner is installed, there are several points to the problem:
1. small central air-conditioning of indoor unit is generally installed in the ceiling, in determining their install location, you should be aware of: (1) indoor installation location near cannot have power (such as electric heaters, gas stoves, etc.) and the steam source, etc. (2) blow out of the air flow through the human activities should be the main plants, no obstructions in the vicinity of the exhaust outlet. (3) host to distance TV, audio, etc. to avoid a meters above the mutual interference.

(4) the air inlet around do not prevent the inhalation of air in placing obstaclesObstructions. (5) away from heat and gas supply Department. (6) at both ends and should leave room for the above. (7) don't get close to high-frequency equipment, high power wireless devices, so as not to interfere with the normal working air conditioning. 2. in determining the small central air outdoor machine installation location, you should be aware of: (1) small central air outdoor machine is generally higher than the domestic split-type air-conditioning, outdoor machine should be installed in the ground or be able to host its weight on the roof, as a result of conditions necessary to take measures to secure fixed (some larger unit cannot mount). (2) to avoid installation in places where combustible gas leak. (3) to keep the air flowing around the outdoor unit, should be left around a certain space. (4) avoid sunshine directly, if necessary with a sun visor, but does not impede ventilation. (5) select the outlet no obstructions. 3. when the installation should be close coordination of the decoration project. Small central air-conditioning at installation time, particularly in the residential installation, the use of each room, decorated in different styles, such as: ceiling height, materials, lighting, such as the layout. During the installation of a small central air-conditioning before must conscientiously to distinguish between the use of the rooms feature, combined with decoration requirements determine how to air from downward and feed back or side of air, and then determine the style of the diffusers. In a outlet lifting units and installation, to acquire all the room ceiling height and material practices, choice of appropriate installation, so you can make new air conditioning system to comply with the safe, practical, aesthetic requirements. To sum up, although the small central air conditioning in our short history, and some of the technology has not matured, but it's there, after all, fill the air conditioning field, it makes small construction and residential customers can enjoy a higher quality of modern air conditioning, also allows existing air-conditioning industry become diversification, both from a technical or market prospects, the small central air conditioning are also huge space for development. As a construction enterprise, you must grasp the development direction of the market, constantly mastering new technologies and new techniques in order to be in a competitive market.
Editorial: Shin Bo Hun

【 Weak current College 】 bearing selection and usage notes---Power By 【 China power house network 】

With social progress and development, the mechanization of production and life has been widely used. Bearing as the machinery is an indispensable part of the scope of its use are also increasingly widespread, because as long as the rotation of the bearing.

Bearings in machinery mainly supporting and reduce friction, thus bearing accuracy, noise, etc. are directly related to the use of machinery and life. But business people always encounter customers that use the best bearings or imported bearing its efficiency is not high, this is related to the use and selection of the bearing. Perhaps some people will say "bearing service and select the user, I only look at what the user wants to sell me something." But as a qualified sales personnel in addition to mastering their own product knowledge, but also proficient in the use of the product, namely doctors-sales, according to the users of ancillary products performance, using criteria to select the best matching bearing. This is the world's major companies popular specialized manufacturing and sales, the way in this

Because bearing type number range, the following will be primarily on the use of the widest range of deep groove ball bearings in use and select some analysis. Want to know about bearing less one can deepen understanding of the bearing.

I. bearing selection

1. the choice of bearing type: bearing type is normally provided by the user's technical staff under products use conditions and withstand the load on the bearing. The main business people understand whether a user's actual load and the selected bearing, if the bearing does not meet requirements, should advise the customer as soon as possible, but the election model unless special products in select models generally does not have any problems.

2. selection of the bearing clearance: users purchase bearings generally only tells what type, grade, rarely on bearing clearance requests, business people must ask the bearing of the conditions of use, including the bearing speed, temperature, combined with tolerance are directly related to the selection of the bearing clearance. General at 3500 RPM motor speed below most CM clearance, such as high temperature and high speed motor requires a relatively large clearance. Bearing clearance after Assembly will bore of swollen and outer circle of narrow and result in a reduction of the quantity of the clearance = interference × 60% (bearing housing is aluminum). For example, prior clearance is bearing Assembly, assembly 0.01mm when interference is 0.01mm, bearing the clearance after Assembly to 0.004mm. In theory, bearing noise zero clearance and life are the best State, but in actual operation taking into account issues such as the temperature rise, the bearing clearance after Assembly to 0.002mm-0.004mm better.

3. selection of oils and fats: fats is generally chosen is depending on the bearing speed, temperature, noise requirements and starting torque, etc., require business people on the various oils and performance very well.

4, bearing seal type selection: bearing lubrication can be divided into oil lubrication and grease lubrication. Oil lubricated bearings usually choose forms bearing grease lubricated bearings for general use shields or sealing rubber seals. Dust cover for high-temperature or use environment good parts, seals Division contact seal and non-contact seal, contact seal dustproof performance but large starting torque, non seal starting torque, the sealing property is not the contact type.

The bearing is currently in auto motor bearing, appliance motor bearings, motor bearings, motor bearings and other health care professions are specialized manufacturing so that bearing noise and life to achieve peak performance.

Second, the bearing should be used for attention

1, shaft and housing tolerances of selection and room control: bearing pressed into the bearing after rotating flexible without blocking. If there are significant rotation not flexible, the axis size is too big, tolerance to go down. If the bearing pressed into the shaft rotation by hand after the apparent "sand" in the sense that it may be that the shaft tolerance is too large or axis of roundness. Therefore, control the shaft and housing tolerances to room control the roundness, the current domestic many manufacturers only tolerance control, control of roundness.

2. bearing Assembly methods: because the bearings are high-precision products, such as improper easily assembled on bearing raceways caused damage, causing damage to the bearing. Bearings in the Assembly should be dedicated mold, cannot beat, when the pressure in the axis forces only small ring, pressurized circle can only force large circle. Assembly required pneumatic or hydraulic, upper and lower mould when the press to from a State level, such as a slant cause bearing Raceway damage due to stress, and the bearings have guide rings.

3. Assembly of foreign bodies to prevent: bearing in the rotor dynamic balance is made easy when the dynamic balance of iron filings into the bearing internal, it is therefore advisable to do dynamic balance before loading bearings. Some manufacturers in order to assemble and convenient, when assembling in bearing Interior coloured some oil or grease lubricated, but often the operations staff is difficult to control, and if oil or grease in the bearing interior product to stay more in the bearings rotate easily along the shaft into the bearing. Bearings, preferably not coated with oil or grease, e.g. non-smear is the control shall be accumulated to stay inside the bearing.

4, paint and Rust prevention: the paint and rust is characterized by multiple in sealed-motor, motor Assembly will sound very good, but putting in the warehouse for some time, the motor noise become very large, remove the bearings have serious rust. Previously many manufacturers will be regarded as bearing problems, through our ongoing publicity, now motor factory was aware of the problems mainly insulating varnishes. The problem is mainly due to the volatile acidity of insulating material at a certain temperature, humidity, corrosive substances, formed under the bearing raceway caused damage to the bearing corroded. The problem is only a selection of good insulating varnishes, and after drying, ventilation time Assembly.

Bearing life is and manufacture, Assembly, use are closely related, must in every aspect, the bearing is the best running conditions, thus lengthens the service life of the bearing.

【 Weak current College 】 direct-fired LIBR absorption chiller room design---Power By 【 China power house network 】

Direct-fired LIBR absorption chiller (hereinafter chiller) applies to the following areas:

1. user area is rich in oil, gas resources;

2. local environmental protection requirements do not allow the use of coal-fired boiler and electric tension or expensive tariffs;

3. oil and gas can be used, should carefully weigh the use of, or the success of fuel gas. General priority using city gas, city gas supply if not, you should consider using a light oil. Heavy oil with a sulphur content higher, generally should not be used.

Been fired LIBR absorption chiller models selection principle

1. choose the burning machine models

Chiller from its use of energy can be divided into fuel oil-, gas-and oil and gas on the dual-purpose type; from functionality can be divided into three-(with refrigeration, heating and sanitary hot water three functions), air conditioning (with refrigeration, heating function) and single cooling (with cooling function). Single cooling two cheaper than before, three-and-price close to the air conditioning. Selection should be based on the user's requirements for water supply parameters; it should also be an economic comparison, to reduce the room for a time investment.

2. determination of load

Determine chiller for cooling (heat) load, except in the calculation of air conditioning load, increasing the unit itself and water system in the cold (hot) loss (usually lo% ~ 15%), consideration should be given to the cold (hot) water and cooling water dirt factors, on the amount of cold (heat). Unit in the refrigeration system of hot water at the same time, the cooling capacity corresponding lower, unless the increase high-voltage generator, this factor should also be considered. Different cold (hot) load, you should choose the burning machine.
General direct machine rated heating capacity is its rated cooling capacity of 80 percent. But they can according to user's requirements, select the quantityof heat is greater than or equal to the cooling capacity of special models. The heating capacity chiller is the heating of heat and hot water heat health, or either (both of which can be individually rated heating capacity).

3, the number of

General use 2-4 chiller, small and medium-sized project selection 2, a large selection of 3, 4 large selection. Unit between mutual as spare and rotate. From easy maintenance management perspective, try to use the same model, same specifications unit, from the standpoint of energy and, if necessary, you can also choose different models and different load unit combination.

4. determination of working pressure

Chiller work pressure, directly affect the cost of its cost and system safety and reliability, should be based on appropriate air-conditioning system, heating and water system, hot water system in the unit set the elevation at the pressure of work, to determine the chiller evaporator, condenser and water heaters work pressure. Homemade chiller of evaporator, condenser and water heater tube bundles of working pressure is 0, 8MPa (standard type) to meet the General requirements of the building, design, priority should be to reduce equipment costs. Located at the top or bottom of super high-rise building basement or absorption unit, its pressure is often more than 0, 80MPa. If you consider that the use of air conditioning water system vertical not partition scheme for safe, reliable and economically reasonable, you can special order to manufacturer selection pressure 0.81 — 1.6MPa's enhanced unit. Otherwise, should take water system partition, decompression measures to reduce the pressure on the bottom of the unit, so that less expensive ordinary unit to apply.

5. determination of fuel

Choose what kind of fuel, according to the local economy of fuel supply situation and identify the technical results of the comparison. When there are reliable sources (city gas or natural gas, etc.), youshould first use gas; when only oil (light or heavy fuel oil), you should first consider the use of light gas oil (diesel). A light oil system, heavy oil system simple and convenient to run management, eliminating the need for heating oil. Of course, if you have a cheap source of heavy fuel oil, should also be taken into account. If the user to predict gas does not completely meet your needs (daily gas peak cause gas shortage or years less than a season volume), you can select the oil and gas dual-fuel dual-purpose type units, in order to meet the different stages of the supply of the particular circumstances of different fuels. Dual-fuel units because it has a dual function, expensive, users should be on the increase and decrease operating costs, reasonable comparison.

2 architectural design of direct-fired machine room

Since chiller for negative pressure operation equipment, its room settings can be set according to the architectural characteristics of flexible. And since chiller to burn oil and gas, natural gas, etc., so the engine room security comparison strict, must meet the national standard specifications for the design of the boiler room, the senior civil building design fire protection standard, the architectural design fire protection standard, the town gas design code, and other requirements.

1, room location

Room location should be set at the desired place of cold, cold load centres in General should consider building the first layer to save covers.

Basement, ground floor, floor, roof can be set in the engine room, but fuelled with liquefied petroleum gas (LPG) and density than air greater gas should not be set in the semi-underground and ground floor of a building or structure. For high-rise building, computer room in the basement or ground floor yishe. Located in the basement, ventilation and drainage more difficult; for super high-rise building, consider room located in the floor or roof. Set up, will bring a rangeof issues, such as water pump room noise and vibration, the crew hoisting, maintenance more difficult, the equipment load on structural design requirements are higher, at present, the lack of experience, must be taken seriously.

If direct combustion in the engine room must be located in the basement, you should think about ventilation and drainage problems, you should also consider lifting and hoisting plan population and reserved; if located in the floor and the roof, you should consider water system design and structural load-bearing and lifting scheme, etc.

Cooling water, cold water pressure too high occasions (e.g. more than o.8MPa), consider room located on the floor or roof. Noise and vibration due to the pump. Water pump room and the host application wall separates the House.

Large and medium-sized cooling machine room should be set first, control room, garage and toilet facilities, or in combination with other room (such as water pumping station, the air conditioning room, etc.). Conditions should be set.

2, room size is OK

First of all should meet the requirements of the unit itself, should stay out of maintenance space, the space around the basic unit of not less than: above about side 1.2m, as 1.5m; the other side as before and after the end of the o.8m 1.5m at one end and leave a washing pipe space (equivalent to the body length in order to facilitate the cleaning of heat exchanger tube). Washing pipe space can take advantage of doors, Windows. Setup 2 or more units when maintenance space can share; second, you should also consider pumping stations, water treatment equipment, power distribution control room, rest room and other subsidiary room dimensions. Located in the basement of the House, if too many over the pipeline, for easy installation, reduced pipe fighting, part of the pipeline underneath the unit. At this time, the room storey you should also consider unit below the overhead piping space (normally clear height of not less than 0.5m) height.

Weak current College】 【analysis of ground source heat and hot water heating system combines the features of.

<br> Because of the heat pump (heat pump, water source heat pumps) for the low-water temperature, which makes it as low-temperature hot water floor heating (hereinafter referred to as the "hot-water floor heating") system .of a heat source. Because of the heat pump in Shijiazhuang application range is becoming more and more widely, it is a heat pump combination with hot-water heating for residents. This article in Shijiazhuang city, district heating system applications, for example, analysis .of ground source heat and hot water heating system based on the combination of features. <br> <br> An introduction to the Garden State <br> <br> Ann residential district is a project of Hebei Commission approval of a large affordable housing projects ., from Shijiazhuang municipal affordable housing development center. Community planning 36 hectares, with a total construction area 33.43 million square meters, can provide boutique residence in the community more than 3000. Community development will enhance the city's image, to speed up the process of urbanization .in the Southeast Division, urban economic prosperity have immeasurable impact. The project is divided into two phases of construction, the first phase of the project already in December 2007 have been delivered to the owner's key. <br> <br> Ann residential district is .located in Shijiazhuang city development main direction - Southeast direction, press the city master plan, the community in the city center. Since no municipal heat supply facilities, combined with the heat pump has several advantages, so the community planning will heat pumps as a heat .source, part of building a water source heat pump, part of the building using ground source heat pump, indoor heating system in the form of low-temperature floor heating. <br> <br> Ground source heat pump technology was born in the mid .-1980s. The technology intelligently leverage storage in the heat of the Earth surface, extracting heat from the ground in winter, the summer heat in the building and placed underground for winter and summer heating and cooling needs energy. Compared with other sources of energy, .this energy is obviously very energy efficient - to produce 100% usable thermal energy, General heating boiler needs a 110% to 120% of primary energy (fuel or gas), and this resource is not renewable, burning after causing environmental pollution. But the .opposite of ground source heat pump system, producing the same amount of heat energy, it only requires a power of 1 / 4, other 3 / 4 of the energy from the nature of the renewable energy in free. Ground source heat pump consists of a .ground-coupled heat exchanger, the switch either horizontally installed in a pit, or to the u-tube vertically mounted in the shaft. Different pipe Groove or shaft of a heat exchanger into parallel connection, and then through a different set pipe enters the building .and building water loop. In the liquid temperature is low, the system needed to join the antifreeze, northern areas of application should pay special attention. <br> <br> On-site survey <br> <br> In the decision to use .ground-source heat pump, related departments on situations in the field have accurate and detailed resources. Although some areas may be ground source heat pump installed because some special situation increases the equipment or installation costs, but most of the region is suitable for installation. .According to engineering practice, the adaptability to any place of the assessment should take full account of the situation of the local geology, including loose soil in the natural state and load the density, soil and water-bearing layers of the situation after the load, .the rock layers of rock bed structure. <br> <br> According to the geological reports, relevant aspects for ground source heat pump system. The beginning of the work on the identification of local conditions, to ensure that the design period to avoid experiencing .potentially complex issues, and design departments also need such information in order to select the most suitable drilling and mining equipment, and you can save a lot of time and money. <br> <br> Programme selection <br> <br> In the .field on the basis of the findings of the investigation to determine the heat exchanger is the layout: layout with a vertical shaft or horizontal layout. <br> <br> On the surface area of the site available is one of the factors must be considered .. <br> In layout, the vertical spacing of 4.6 meters above sea level, this is to ensure that in most cases the shaft between the thermal noise and (or) is the accumulation of heat is negligible, and you can guarantee that after that .determine the various parameters of the shaft to meet design requirements. <br> <br> Although the double u-tube/shaft structure of heat than single u-tube/shaft structure per ton of heat exchanger requires additional pipeline, but assessment showed that .for less drill shaft and savings can compensate for the increase in the number of pipeline and increased costs. <br> <br> Parallel pipe vertical heat exchanger and in-line pipe vertical heat exchanger, u-tube wells can be smaller, which can .reduce costs, cost pipeline antifreeze. Due to the smaller pipe making easier, labour costs may also be reduced. And U-shaped tube diameter of the shaft diameter is reduced correspondingly smaller, drilling costs can be reduced correspondingly. Parallel pipe heat exchanger same loop .sets all of the connected shafts of heat radiation is the same, and in-line heat exchanger each shaft of heat is different. <br> <br> Vertical soil heat exchanger depending on the load of the building. Building load is building type, .size, position, internal load (that is, the device uses heat, lighting, heating), outdoor air permeability, solar radiation heat gain and maintain structures and ventilation function. Other soil heat exchanger volume along with the average temperature and overburden (soil) .and rock, underground floors have heat transfer coefficient, the efficiency of heat pump and heat exchanger tube size. <br> <br> Ground source heat pumps and water heating to warm the advantages of combining <br> <br> Ground source heat pump .system with very little outdoor equipment and rooms can be arranged in the basement, saving costly maintenance and security costs. There is no roof, no roof-bearing, modification or obscurations, greatly reducing the external noise and architectural beauty has been very well maintained. .<br> <br> Residential community using ground source heat pump is an important reason - will give developers bring great benefits. The benefits of using ground source heat pumps, for those who do not have municipal heat supply of the community particularly obvious. And .municipal heat supply of the community can also use ground-source heat pump. This is because municipal heat supply interface charges quite expensive: residential General 40 Yuan / square meter, andThe Government has a file, prohibiting the developer from the owners receive heating set tariff .. On the other hand, the ground-source heat pump running cost is low, but the Government has not yet promulgated file specific provisions to the heat pump to heat source of community residents in winter heating costs charged value. Currently the owners pay for the .class fee and municipal heating heating heating period the same, ie (4 months) 18.4 Yuan / square meters. In this way, you can get some property companies. In the garden, indoor heating is used in low-temperature floor heating. Because of .the heat pump of water temperature is 50 ° c ~ 60 ° c and meets the radiant floor heating system is not higher than 60 ° c, without increasing the heat transfer equipment, significantly reducing investment, this is also combined the two greatest advantage. < .br> <br>.