1, determine the specific type of gear pump

After determining what series of pumps to choose, you can press the larger flow, (in the absence of larger flow, usually take 1.1 times of the normal flow as the larger flow), take the enlarged margin of 5%-10% of the head of these two performance parameters, in the spectrum or series of characteristics of the curve to determine the specific model.The operation is as follows:

Use of pump characteristic curve, find the flow on abscissa values, find the head on the ordinate, upward from the two values, respectively, and lead to the right vertical or horizontal line, two line intersection point lies squarely on the characteristic curve, it is to choose the pump, but this ideal rarely, often meet with the following two conditions:

One: the intersection point is above the characteristic curve, which indicates that the flow meets the requirements, but the head is not enough. At this point, if the head is similar, or the difference is about 5%, you can still choose. If the head differs a lot, you can choose a pump with a larger head.Or try to reduce the line resistance loss.

Two kinds: intersection point under the characteristic curve, in the pump characteristic curve fan trapezoid range, on the preliminary set this model, and then according to how much difference in head, to decide whether to cut impeller diameter,

If the head difference is very small, do not cut, if the head difference is very big, according to the required Q, H, according to its NS and cutting formula, cutting impeller diameter, if the intersection point does not fall in the range of the fan trapezoid, should choose the pump with a smaller head.When choosing pump, sometimes must consider the production process requirements, choose different shape Q-H characteristic curve.

2. According to the nature of the liquid medium, determine whether the cleaning pump, hot water pump or oil pump, chemical pump or corrosion resistant pump or impurity pump, or use non-clogging pump.

The pump installed in the explosion area shall adopt corresponding explosion-proof motor according to the grade of the explosion area.

3. Select horizontal, vertical and other types (pipe type, diving type, liquid type, non-clogging type, self-pription type, gear type, etc.) pumps according to the arrangement of devices, topographic conditions, oil level conditions and operating conditions.

4. After the pump model is determined, for pumps or pumps with physicochemical medium similar to oil, it is necessary to go to the relevant product catalog or samples and modify according to the performance table or performance curve of the model to see whether the normal working point is in the preferred working area of the pump.Whether the effective NPSH is greater than (NPSH).Can you also reverse the NPSH correction to the geometric mounting height?

5, according to the flow, determine the single suction pump or double suction pump;According to the height of the head, single-stage pump or multi-stage pump, high speed pump or low speed pump (air conditioning pump), multi-stage pump efficiency is lower than single-stage pump, such as single-stage pump and multi-stage pump can also be used, the first choice of single-stage pump.

Determine the number of pumps and reserve rate:

For the normal operation of the pump, generally only one, because a large pump and parallel operation of the two small pump equivalent, (refers to the same head, flow rate), large pump efficiency is higher than small pump, so from the point of view of energy conservation would rather choose a large pump, rather than two small pumps, but in the following circumstances, you can consider two pump parallel cooperation:

The flow is very large, a gear pump can not reach this flow.

For large pumps that require a 50% spare rate, two smaller pumps can be changed to work with two spare pumps (three lifts in total)

For some large pumps, can choose 70% flow requirements of the pump parallel operation, no spare pump, in a pump overhaul, another lift pump is still responsible for the production of 70% of the transport.

6. For liquid pumps with viscosity greater than 20mm2/s (or density greater than 1000kg/m3), it is necessary to convert the characteristic curve of oil experimental pump into the viscosity (or the density under) performance curve, in particular, it is necessary to carefully calculate the suction energy and input power or core.

7, to determine the number of gear pump and standby rate:

For the normal operation of the pump, generally only one, because a large pump and parallel operation of the two small pump equivalent, (refers to the same head, flow rate), large pump efficiency is higher than small pump, so from the point of view of energy conservation would rather choose a large pump, rather than two small pumps, but in the following circumstances, you can consider two pump parallel cooperation:

The flow rate is too high for one pump to reach.

For large pumps that require a 50% spare rate, two smaller pumps can be modified to work with two spare pumps (three in total).

For some large pumps, can choose 70% flow requirements of the pump parallel operation, do not need to spare pump, in a pump overhaul, another pump is still responsible for the production of 70% of the transport.

For pumps that need to operate continuously for 24 hours, there should be three spare pumps, one for operation, one for standby and one for maintenance.

8. In general, customers can submit their basic conditions for choosing pumps, and our company will give selection or recommend better pump products.If the design institute in the design of equipment, the pump model has been determined, according to the design institute requirements.

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