According to pump selection principle and selection of basic conditions, the specific operation is as follows:
1. According to the layout of equipment, topography, water level conditions and operating conditions, the choice of horizontal, vertical and other types (pipeline type, submersible type, submerged type, non-clogging type, self-priming type, gear type, etc.) Pump.
2, according to the nature of the liquid medium to determine the water pump, hot water pump or pump, chemical pump or corrosion-resistant pump or impurity pump, or non-clogging pump.
Pumps installed in the explosive area should be based on the explosion area level, using the appropriate explosion-proof motor.
3, according to the size of the flow, to determine the menu suction pump or double suction pump; according to the level of the head, single-stage pump or multi-stage pump, high speed pump or low speed pump (air conditioning pump) Single-stage pump and multi-stage pump can also be used when the first choice of single-stage pump.
4, to determine the specific type of pump
After determining which pump to use, you can press the maximum flow, (in the absence of the maximum flow, it is usually desirable to 1.1 times the normal flow as the maximum flow), take 5% -10% head lift after the performance of these two The main parameters, in the spectrum or series of curves to determine the specific model. Operation is as follows:
Use the pump characteristic curve to find the desired flow value on the abscissa and the desired lift value on the ordinate. Draw the vertical or horizontal lines from the two values, respectively, and the intersection of the two lines falls exactly on the characteristic curve. The pump is the pump of choice, but the ideal situation is usually very small, usually encounter the following two situations:
The first: the intersection point in the characteristic curve above, indicating that the flow to meet the requirements, but the lift is not enough, this time, if the lift is about the same, or a difference of about 5%, can still be used, if the lift a lot of difference, . Or try to reduce the pipeline resistance loss.
The second: the intersection point below the characteristic curve, in the fan characteristic trapezoidal trapezoidal range, it is initially set under this model, and then according to how much head difference, to decide whether to cut the impeller diameter,
If the head difference is small, do not cut, if the head is a big difference, according to the required Q, H, according to its ns and cutting formula, cut the impeller diameter, if the intersection does not fall within the range of fan-shaped trapezoidal, Small pump. Pump selection, and sometimes have to consider the production process requirements, choose different shape QH characteristic curve.
5, the pump model is determined, the pump or transport medium near the water of the physical and chemical pump, need to go to the relevant product catalogs or samples, according to the model performance chart or performance curve correction to see whether the normal working point falls on the Pump priority work area? The effective NPSH is greater than (NPSH). Can also be reversed in order to NPSH geometric installation height?
6, for the delivery of liquid viscosity greater than 20mm2 / s (or density greater than 1000kg / m3), be sure to test the pump characteristics of the water into the viscosity (or the density) of the performance curve, especially for the inhalation performance and Input power carefully calculated or more nuclear.
7, to determine the number of pumps and spare rate:
The normal operation of the pump, generally only one, because a large pump and parallel work of two small pumps, (referring to the head, the same flow), the pump efficiency is higher than the small pump, so from the point of view of energy-saving options rather Ning Taiwan big pump, rather than two small pumps, but in the case of the following circumstances, consider the two pumps in parallel cooperation:
A lot of traffic, a pump can not reach this traffic.
For large pumps that require a 50% standby rate, two smaller pumps can be changed to work, two for backup (three in total)
For some large pumps, pumps with a 70% flow rate can be used in parallel without a backup pump. When one pump is undergoing overhaul, the other pump still takes over 70% of the production.
On the need for 24 hours of continuous operation of the pump, spare pump should be three, one running, a spare, a maintenance.
8, under normal circumstances, customers can submit their "basic conditions of pump selection", given by the Division I choose or recommend a better pump products. If the design institute in the design of equipment, the pump model has been determined, according to the design institute requirements configuration.
9, to determine the number of pumps and spare rate:
The normal operation of the pump, generally only one, because a large pump and parallel work of two small pumps, (referring to the head, the same flow), the pump efficiency is higher than the small pump, so from the point of view of energy-saving options rather Ning Taiwan big pump, rather than two small pumps, but in the case of the following circumstances, consider the two pumps in parallel cooperation:
A lot of traffic, a pump can not reach this traffic.
For large pumps requiring a 50% standby rate, two smaller pumps can be changed to work, with two spares (total of three)
For some large pumps, the pump with 70% of the flow rate can be selected for operation in parallel without a spare pump. When one pump is undergoing maintenance, the other pump still takes 70% of the production.
On the need for 24 hours of continuous operation of the pump, spare pump should be three, running, a spare, a maintenance.
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