2015年1月25日星期日

Detailed Instructions of Choosing Pumps Part 1

According to the basic principles presented before and the basic conditions, the detailed instructions are as below: 1. According to the layout, terrain conditions, water conditions, operating conditions of the device, make sure to choose horizontal, vertical, or other types pump (pipeline, diving, liquid-type, non-clogging, self-priming, gear, etc.). 2. According to the nature of the liquid medium to determine if clear water pump, heat pump, oil pump, chemical pump/ corrosion resistant pump, trash pump or non-clog pump. Note: When pump installed in explosive areas, based on the regional level of the explosion, the corresponding explosion-proof motors should be applied. 3. According to the flow, make sure to choose single suction pump or double suction pump; according to head level, choose single stage pump or multi stage pump, or high speed pump and low speed pump (air conditioning pump). Take note that the efficiency of multi-stage pump is lower than that of single-stage pump, when both single-stage pump and multi-tage pumps can be used at the same time, the first choice is single-stage pump. 4. Choose the specific model of the pump After choosing which series of Screw Pumps are used, you can according to the maximum flow rate (in the absence of the maximum flow rate is usually desirable to 1.1 times of the normal flow rate as the maximum flow rate), take an enlarged head 5% -10%, the balance of these two properties after the main parameters to determine the specific model or series on the type spectrum characteristic curve. Operation is as follows: Using a pump characteristic curve, find the desired flow values on the horizontal axis, find the lift values on the vertical axis, up and to the right from the two values cited vertical or horizontal line, right on the intersection of two lines characteristic curves, the pump is the right choice, but this ideal situation is rare, usually run into the following two conditions: The first: the intersection is above over the characteristic curve, which shows the flow meet the requirements, but the head is not enough, in this situation, if the head is almost the same, or a difference of about 5%, you can still choose this pump, while a lot of difference, it’s suggested to select larger head pump. Or try to reduce pipeline pressure loss. The second: the intersection is at the bottom of the characteristic curve, when it’s inside of the characteristic curve trapezoidal range, you can choose this model, and then depending on difference of head, decide whether to cut the impeller diameter. If the head difference is small, do not cut, if the head a big difference, according to the desired Q and H, based on their ns and cutting formula, cut impeller diameter, if the intersection does not fall within the scope of the fan trapezoid, to select small head pump. When selecting a pump, sometimes you have to consider the production process requirements to choose different shapes Q-H characteristic curve. Honghai pump. More instructions will be updated soon.

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