According to the gear pump selection principle and selection of basic conditions, the specific operation is as follows: 1, according to the layout of the device, topography, water conditions, operating conditions, to determine the choice of horizontal, vertical and other types (pipe, submersible, The following formula, non-clogging, self-priming, gear, 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, Determine the specific type of gear pump to determine the choice of what series of pumps, you can press the maximum flow, (in the absence of maximum flow, it is usually desirable to 1.1 times the normal flow as the maximum flow), take 5% -10% margin After the lift of the two main parameters of performance, in the spectrum or series of characteristic curve to determine the specific model. The operation is as follows: Use the pump characteristic curve, find the required flow value on the abscissa, find the required lift value on the ordinate, from the two values ​​were drawn up and down, respectively, vertical or horizontal line, intersection of two lines just fall in the characteristic curve , Then the pump is the pump to be selected, but this ideal situation is generally 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 not enough head, this When the lift is almost the same, or a difference of about 5%, can still be used, if a lot of head difference, then choose a larger head pump. Or try to reduce the pipeline resistance loss. The second: the intersection of the curve below the characteristic curve, in the fan characteristic trapezoidal trapezoidal range, initially set this model, and then according to head difference between how much to decide whether to cut the impeller diameter, if the head difference is small, do not cut, if According to the required Q and H, according to its ns and cutting formula, cut the impeller diameter, if the intersection does not fall within the range of fan-shaped trapezoid, should choose a pump with smaller head. 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 gear pump and spare rate: For 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), large pump efficiency Therefore, it is better to choose a large pump rather than two smaller pumps in terms of energy saving. However, in the following cases, two pumps may be considered in parallel connection: a large flow rate and a single pump can not reach this flow rate. For large pumps requiring a 50% standby rate, two smaller pumps can be changed and two spares (totaling three) can operate in parallel for some large pumps with a choice of 70% flow rate, without a backup pump, When one pump is undergoing maintenance, the other pump still carries 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, the customer can submit the basic conditions of its election pump, given by the Division I choose 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 configuration. 9, to determine the number of pumps and spare rate: For 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 rather choose a large pump rather than two small pump, but in the following cases, consider the two pumps in parallel cooperation: a large flow, a gear pump can not reach this flow. For large pumps requiring a 50% back-up rate, two smaller pumps can be changed to work with two spares (for a total of three). For some large pumps, a pump with a 70% flow rate can be used in parallel without a backup pump, When one pump is undergoing maintenance, the other pump lift still assumes 70% of the delivery on 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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