How to choose a suitable melt pump extrusion?

　　How to choose a suitable melt pump extrusion?

　　The melt pump extrusion selection principle and the basic conditions for the selection, as follows:

　　1, according to the arrangement, terrain conditions, water conditions, operating conditions of the device, determine the choice of horizontal, vertical, and other types (pipeline, diving, liquid-type, non-blocking, self-priming, gear, etc.) pump.

　　2, according to the nature of the liquid medium to determine the water pump, heat pump or pumps, chemical pumps or Naifushibeng or trash pump, or the use of non-clog pump.

　　Pumps installed in explosive areas, should be based explosive area classification, with the corresponding proof motors.

　　3. The size of the flow, determine the menu or double suction pump suction pump; according to lift height, menu-level pump or multi-stage pump, high-speed pumps or low speed pump (air conditioning pump), multistage pump efficiency is lower than the single-stage pump, such as menu-level and multi-stage pumps can use the same pump, the first choice of single-stage pumps.

　　4, to determine the specific types of stainless steel melt extrusion pump

　　What determines the choice of the series of pumps, the maximum flow can press, (in the absence of the maximum flow rate, typically preferably 1.1 times the normal flow rate as the maximum flow rate), an enlarged head takes 5% -10% of the balance of these two properties after The main parameters to determine the type of specific models or series of characteristic spectrum. Proceed as follows:

　　Using a pump characteristic curve, find the required flow values ​​on the horizontal axis, find the lift values ​​on the vertical axis, from the two values ​​lead up and right vertical or horizontal line, right on the intersection of two lines characteristic curves, the The pump is to choose a pump, but this ideal situation rarely, usually run into the following two conditions:

　　The first: the intersection of the characteristic curve upward, indicating that flow to meet the requirements, but the head is not enough, this time, if the head almost the same, or a difference of about 5 percent, still the choice, if the head is far too small, then choose a larger pump head . Or try to reduce the pipeline pressure losses.

　　The second: the intersection at the bottom of the characteristic curve, the pump characteristic curve in trapezoidal fan range, the initial set of this type, then how much difference according to the head, to decide whether to cut impeller diameter,

　　If the head difference is small, do not cut, if the head a big difference, just press the desired Q, H ,, according to its ns and cutting formula, cutting impeller diameter, if the intersection does not fall within the scope of the trapezoid fan, to be elected head compared small pumps. When selecting a pump, sometimes we have to consider the production process requirements, use of different shapes QH characteristic curve.

　　5, the pump model is confirmed, to approximate physical and chemical medium water pump water pump or the transmission medium is required then the relevant catalog or samples for corrections to the table based on the model performance or the performance curve, see the normal operating point falls within the Pump priority area? effective NPSH is greater than the (NPSH). NPSH can also turn to the geometric corrections to mounting height?

　　6, for the delivery viscosity greater than 20mm2 / s of liquid pump (or a density greater than 1000kg / m3), must take the test water pump characteristic curve in terms of the viscosity (or the density) of the performance curve, in particular for suction performance and Input power for serious computing or less nuclear.

　　7, stainless steel melt pump extrusion determine the number of units and standby rate:

　　The normal operation of the pump, generally only one, because a large pump and two small pumps working in parallel rather, (refer to head, the same flow), large pumps more efficient than small pump, so to speak from the energy point of view rather optional one NTU pump instead of two small pumps, but in case of the following situations, consider two pumps in parallel cooperation:

　　High traffic, a pump can not reach this traffic.

　　50% of the need for a large spare pump rate, can be changed two smaller pump, two spare (total of three)

　　For some large pumps, the choice of 70% of the pump flow requirements parallel operation, do not spare the pump when a pump overhaul, another pump still bear 70% of the production of transport.

　　Required 24 hours of non-stop operation of the pump, it should spare three pumps, one run, a backup, a repair.

　　8, under normal circumstances, customers can submit their election pump basic conditions given by the Division I selection or recommend a better pump. If the institute in the design of plant equipment, the type of pump has been determined, according to the Institute configuration requirements.

　　9, determine the number of units and spare pump rate:

　　The normal operation of the pump, generally only one, because a large pump and two small pumps working in parallel rather, (refer to head, the same flow), large pumps more efficient than small pump, so to speak from the energy point of view rather optional one NTU pump instead of two small pumps, but in case of the following situations, consider two pumps in parallel cooperation:

　　High traffic, a stainless steel melt pump extrusion reach this traffic.

　　50% of the need for large pumps alternate rate, can be changed two smaller pump, two spare (a total of three lift)

　　For some large pumps, the choice of 70% of the pump flow requirements parallel operation, do not spare the pump when a pump overhaul, another lift pump still bear 70% of the production of transport.

　　Required 24 hours of non-stop operation of the pump, it should spare three pumps, running, a backup, a repair.