According to the gear pump selection principles and basic conditions, the specific operation is as follows:
1: Gear Pump Installation arrangement
According to the arrangement of the device, terrain conditions, water level conditions, operating conditions. Determine the choice of horizontal, vertical and other types. Such as (pipe type, submersible, liquid type, non-blocking, self-priming, gear type, etc.) gear pump.
2: Nature of liquid medium
According to the nature of liquid medium, determine water gear pump, hot water gear pump or stainless steel gear pump or corrosion resistant gear pump or impurity gear pump. Or the use of non-blocking gear pump.
The gear pump installed in the explosion area should adopt the corresponding explosion-proof motor according to the explosion area grade.
3: Flow size
According to the flow size, determine the single suction gear pump or double suction gear pump. According to the head height, choose single-stage gear pump or multi-stage gear pump. High speed gear pump or low speed gear pump (air conditioning gear pump). High speed gear pump ought to use high speed jaw shaft coupling. Multi-stage gear pump efficiency is lower than single-stage gear pump. Such as single-stage gear pump and multi-stage gear pump can also be used, first choose single-stage gear pump.
4: Characteristic Curve of Gear Pump
Determine the specific type of the gear pump, make sure to choose what series gear pump, can according to the maximum flow. (when there is no maximum flow, usually the normal flow of 1.1 times the maximum flow), take up 5% - 10% allowance after the head of the two main parameters. The performance of the spectrum chart or series of characteristic curve to determine the specific models. The operation is as follows:
Using gear 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. Then the gear pump is to choose the gear pump. But this ideal is generally very few, often meet with the following two conditions:
Conditions
(1) Intersection above the characteristic curve, which shows that the flow meets the requirements. But the head is not enough, at this time, if the head is similar, or 5% or so, can still be selected. If the head difference is a lot, then choose the larger head gear pump. Or try to reduce line resistance losses.
(2): Intersection point below the characteristic curve, in the gear pump characteristic curve fan trapezoid range, the model is initially set, and then according to the head difference, to determine whether to cut the impeller diameter.
If the head difference is very small, do not cut, if the head difference is very large, according to the required Q, H. According to the cutting formula, cutting impeller diameter, if the intersection does not fall in the fan trapezoid range, should be selected with small head gear pump. Gear pump selection. Sometimes must consider the production process requirements, the selection of different shapes q-H characteristic curve.
5: Determined gear pump selection model
After the type of gear pump is determined, the water gear pump or the physical and chemical medium of the transmission medium is nearly like water gear pump. And then to the relevant product catalog or sample, according to the model performance table or performance curve correction. To see whether the normal working point falls in the priority working area of the gear pump.
6: Viscosity
For the conveying viscosity is greater than 20mm²/s of the liquid gear pump (or density is greater than 1000kg/m3). Be sure to convert the water experimental gear pump characteristic curve into the viscosity (or the density) of the performance curve, especially to the absorption energy and input power carefully calculated or core. For liquids with viscosity greater than 1000cst, the pump must be equipped with a gear motor to reduce speed.
7: Pumps Number of units and reserve rate
Determine the number of gear bitumen pump and reserve rate: For normal operation of the gear pump. Usually only one. Because a big gear pump with the parallel operation of two small gear pump, (the head and flow rate is the same). Big gear pump efficiency is higher than the small gear pump, therefore, from energy saving point of view would rather choose a big gear pump. Instead of two small gear pump. But in case any of the following circumstances, can consider to two sets of gear pump in parallel cooperation:
Flow is very large, a gear pump can not reach the flow.
For the need to have 50% of the reserve rate of large gear pump, can be changed to two smaller gear pump work, two standby (a total of three).
For some large gear pumps, can choose 70% flow requirements of the gear pump parallel operation, no spare gear pump. In a gear pump maintenance, another gear pump is still responsible for 70% of the production of transport.
The need for 24 hours of continuous operation of the gear pump, should be standby three gear pumps, a running, a standby, a maintenance.
8: Choose the basic conditions of gear pump
Under normal circumstances, customers can submit their "basic conditions of gear pump". By the pump manufacturing enterprises to give the selection or recommend better gear pump products. If the design institute in the design of equipment, gear pump type has been determined, according to the requirements of the design institute configuration.
Gear pump selection to consider the work pressure, flow, speed. Quantitative or variable, variable way, volume efficiency, total efficiency, life and prime mover type, noise, pressure pulsation rate, self-priming ability. Also consider the compatibility with hydraulic oil, coupling type, size, weight, etc. These factors, some have been written in the product sample or technical data, to carefully study. Unclear place is best to consult regular gear pump manufacturers related gear pump selection manual content.
