Weak current College】 【pump knowledge (2).

<br> <br> Pump parameters <br> 1, the flow q <br> Flow is the pump in unit time transporting out liquid volume (volume or weight). <br> Volume flow rate Q said units used are: m3 / .s, m3 / h, l / s. <br> Quality flow using Qm representation, the unit is: t / h, kg / s, etc. <br> Mass flow rate and volume flow of: <br> Qm = ρQ .<br>-Ρ-liquid density (kg/m3, t/m3), room temperature water ρ = 1000kg/m3. <br> 2. lift h <br> Lift is a water pump is pumping unit weight liquid inlet from the .pump (pump inlet flange) to pump outlet (pump outlet flange) energy value. That is a Newtonian liquids obtained through effective energy pump. Its unit is N · N = m / m, that is, the pump pumping liquid liquid column height, .used for short m. <br> 3. rotational speed n <br> Speed is the pump shaft revolutions per unit of time, expressed by the symbol n, the unit is the r / min. <br> 4, NPSH NPSH <br .> NPSH also called net positive suction head, is that the main parameters of cavitation performance. NPSH internally used Δ h said. <br> 5. power and efficiency <br> Pump power usually refers to the input power, that is, the original .motivation to support shaft power on, so it is called axis power, expressed with P; <br> Pump power also known as the output power, using Pe. It is the unit of time from the pump delivery out of liquids in pump of effective .energy. <br> Since the head is the pump output unit weight liquid from the pump the effective energy, therefore, lift and mass flow rate and the product of the gravitational acceleration is the unit of time from the pump output of liquid obtained by effective .energy - that is, the effective power of the pump: <br> Pe = ρgQH (W) = γQH (W) <br>-Ρ-pump liquid density (kg/m3); <br> Γ-pump liquids of severe .(N/m3); <br> Q-pump flow (m3 / s); <br> H-pump head (m); <br> G-gravity Acceleration (m/s2). <br> Shaft power P and .the difference between the effective power Pe as a loss of power within the pump, the size used to measure the efficiency of the pump. Pump efficiency as the effective power and shaft power ratio, η said. <br> What is flow? what letters .? how to conversion? <br> Unit time pump discharge liquid volume called flow, flow with Q said measurement unit: m3/hour (m3 / h), in liters / second (l / s), L / s = 3.6m3 / .h = 0.06m3/min = 60L/min <br> G = GQ ρ ρ for weight as liquid specific gravity <br> Example: a pump flow 50m3 / h, the weight per hour when pumping? water density ρ is 1000 kg / .m3. <br> Solution: G = Q ρ = 50 x 1000 (m3 / h · kg/m3) = 50000kg / h = 50t / h <br> What is head? what letters? what measurement units conversion and pressure? and .formula? <br> Unit weight liquid obtained by pump energy called lift. Pump head cover suction, approximate to pump outlet and inlet pressure difference. Lift with H, units are meters (m). Pump pressure P said, Mpa (MPA), .H = P / ρ. If p is 1kg/cm2, H = (lkg/cm2) / (1000kg/m3) H = (1kg/cm2) / (1000 kilograms/m3) = (10000 kg/m2) / 1000 kg ./ m3 = 10m1Mpa = 10kg/cm2, H = (P2-P1) / ρ (P2 = outlet pressure P1 = inlet pressure) <br> What is NPSH? what is suction units represent the respective? letters? <br> Pump working .liquid inlet of the impeller for certain vacuum pressure will produce vapour, vaporization of the liquid bubble in a particle impact campaign, the impeller and other metal surface erosion, thus undermining the impeller and other metal, the vacuum pressure is the pressure of vaporization, NPSH .refers to the entrance of the suction pump unit weight of the liquid exceeds vaporization pressure surplus energy. Unit, dimensioning with m (NPSH) r. Suction is required NPSH Δ h: the pump allows absorption liquid vacuum degree, ie pump allows the height of .the installation, the unit used m. <br> Îü ³ ì = ± ê (10.33 m)-NPSH-security (0.5 m) <br> Standard atmospheric pressure can pressure pipeline vacuum height 10.33 m. <br> For example: a pump required .NPSH 4.0 m, suction Δ h? <br> Solution: Δ h = 10.33-4.0-0.5 = 5.83 m <br> Multi-functional water pump controls the valve standards <br> The technical requirements of the standard are described below: < .br> 1 pressure-temperature degree level <br> Multi-functional water pump controls the valve-pressure-temperature rating by shell, internals and control management system materials for pressure-temperature rating. Multi-functional water pump controls the valve at a temperature .of maximum allowable working pressure from shell, internals and control management system materials at a temperature below maximum allowable working pressure value for the minimum value. <br> 1.1 iron shell of pressure-temperature rating shall conform to GB/T17241.7. <br .> 1.2 steel shell of pressure-temperature rating shall conform to GB/T9124. <br> 1.3 for GB/GB/T9124 T17241.7, does not provide for pressure-temperature rating of the material, the relevant standard or design requirements. < .br> 2 valve body <br> 2.1 valve flange <br> The flange should be made with the body as a whole. .Steel flange types and dimensions shall conform to GB/T17241.6, technical conditions shall conform to GB/T17241.7; steel flange types and dimensions shall conform to GB/T9113.1, technical conditions shall conform to GB/T9124. <Br .> 2.2 body length of structure are shown in table 1. <br> 2.3 minimum wall thickness of the valve body <br> Cast iron body of minimum wall thickness shall conform to GB/T13932-1992 in table 3, casting the minimum wall thickness .of the valve should be consistent with the JB/T8937-1999 in table 1. <br> 3 cover the diaphragm holder <br> 3.1 bonnet and patch, patch-seat and the valve connection flange type should be used. <br> 3.2 .diaphragm, and the number of the connection bolt valve shall not be less than four. <br> 3.3 bonnet and the diaphragm of the minimum wall thickness according to 2.3 requirements. <br> 3.4 bonnet and a flange of diaphragms seat should be round. .Flange type of sealing the surface may be flat or raised, plane type or bump-type. <br> 4 valve stem, valve plate gently closed, main valve plate <br> 4.1 slow closing valve and the valve should be connected fastening and reliable .. <br> 4.2 slow closing gate and the main valve plate sealing type should use metal sealed type. <br> 4.3 main valve plate and slide the stem must be flexible and reliable. <br> 4.4 main gate and the main valve seat sealing .can be metal seal and non metallic seals two type. <br> 5 the diaphragm <br> 5.1 patch performance shall conform to table 2 (see next page). <br> 5.2 appearance quality of the diaphragm should be consistent with the provisions of .the HG/T3090. <br> 5.3 when applied to drinking water, the security of the diaphragm material shall conform to GB/T17219. <br> 6 control management system <br> Control tube system components should be capable of withstanding a valve maximum .operating pressure, the site shall not be compromised. <br> 7 material <br> 7.1 main spare part material selection should be JB/T5300. <br> 7.2 copper alloy castings shall conform to GB/T12225; gray iron castings shall conform to .GB/T12226, its tensile strength should be not less than 200MPa; ductile iron castings shall conform to GB/T12227; carbon steel castings shall conform to GB/T12229; austenitic steel castings shall conform to GB/T12230. <br> 7.3 steel multi .-functional water pump controls the valve castings appearance quality should be consistent with the provisions of the JB/T7927, iron castings, multi-functional water pump controls the valve appearance quality reference JB/T7927. <br> 8 shell strength <br> Multi .-functional water pump controls the valve-body strength shall conform to GB/T13927. <br> 9 sealing performance <br> Multi-functional water pump controls the valve sealing performance shall conform to GB/T13927. <br> 10 cleanliness <br .> Cleanliness of multi-functional water pump controls the valve should be consistent with the provisions of the JB/T7748. <br> 11 painting <br> When you applied to drinking water, multi-functional water pump controls the valve cavity finishing materials security .shall conform to GB/T17219. The outer surface of the coating is not required, special requests in the order indicated in the contract. <br> <br> <br> <br>.