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What are the flow rates of mechanical diaphragm metering pumps

- Nov 20, 2017 -

What are the flow rates of mechanical diaphragm metering pumps?

Flow rate of mechanical diaphragm metering pump

The flow rate of mechanical diaphragm metering pump is divided into theoretical flow, rated flow, maximum (measured) flow and stroke flow.

(1). The theory of flow without considering any volume loss of the pump, according to the main structure parameters of the pump (maximum stroke volume) and pump flow rate calculation; (2). The rated flow in rated conditions (temperature and pressure), the design of the pump should be prescribed during normal operation of pump outlet the flow of nominal value; (3). The maximum (measurement): flow at rated conditions (temperature, pressure) and the maximum (100%) stroke, the pump in normal operation when the measured discharged from the pump outlet flow; (4). Travel flow: at rated conditions (temperature and pressure) under the normal operation of the pump in the specified travel from the pump outlet measured discharge flow; according to the national standard (GB/T7782-2008 mechanical diaphragm metering pump) stipulates that "the actual flow of the pump at rated conditions shall not be lower than the rated pump capacity value 。” The actual flow rate under the rated condition should be controlled within the "(100~120)% rated flow value" stipulated in the quality classification of JB/T53192-1999 mechanical diaphragm metering pumps. API675-1994 (R2000) "volumetric pump mechanical diaphragm metering pump" standard stipulates that the rated capacity should be at least 110% of the maximum capacity required." (5). The actual flow of the pump: mechanical diaphragm metering pump at rated conditions (maximum range, rated pressure, rated conditions), the actual flow rate is generally greater than the rated flow pump value for the flow of values not according to the length of the rated flow multiplied by the stroke of the percentage of simple calculation, but can not be this calculated and measured the error according to the measurement accuracy assessment of pump, metering pump in the specified accuracy assessment only travel flow stability accuracy and reproducibility precision, has nothing to do with the specific value. 9) performance curve of mechanical diaphragm metering pump:

The performance curves of the 7 mechanical diaphragm metering pump is indicative of the pump stroke, corresponding flow in different size under pressure, it mainly has two, namely the stroke and flow pressure and flow rate (Q-S) and (Q-P), the change curve of travel and the flow curve is the main user guide. The pump performance curve can only be based on the pump in the factory test, according to the provisions of "test method of mechanical diaphragm metering pump" standard, measured flow value in different pump stroke and pressure, through the calculation of the pump flow calibration curve, when using the user's difference and test conditions at the factory can the factory in accordance with the flow calibration curve for flow control of the pump. According to the national standard test, mechanical diaphragm metering pump factory test is carried out in accordance with the room temperature water conditions (except for special dielectric diaphragm metering pump quality test specified by the user), if the medium and condition of user and factory testing physical properties (temperature, density, viscosity, particle size differences, etc.) in official use first, users should use the transmission medium, re calibration of flow curve under the operating conditions. In the bidding or ordering, users often ask us to improve the performance curve of the pump, these curves can only be theoretical (or empirical), and can not replace the actual performance curve of the pump. The theory of performance curve of mechanical diaphragm metering pump should be a straight line, but not 45 degrees (100% stroke point and maximum flow value of the length of the line set the same), should be more than 46 degrees; the starting point is not in the diagonal of 0 points, but 3% to 6% stroke point position of partial process big small flow and high pressure; less than 10% diagonal dashed lines, because < 10% error travel flow is large, generally do not check; the maximum flow rated pressure is generally 110% of the rated flow, the higher the rated pressure flow rich degree is smaller, the real flow and theoretical flow under the zero pressure close to. 3. the characteristics of reciprocating displacement pump 1) structural characteristics: with Yu Zhu (Live) plug or other elastic components in the liquid cylinder working chamber reciprocating movement, resulting in a cyclical change in the volume of work. The working chamber is separated from the outside by the sealing device (packing and valve group) and communicated with the pipeline system through the valve (suction and discharge valve group). 2) performance characteristics: several assumptions of hydraulics research: A. fluid is continuous; B. transport medium is incompressible; C. does not take into account the influence of viscosity. (1) instantaneous flow is pulsating: a) the reciprocating pump has the suction and discharge process. (b) column (Live) plug in the displacement process, the speed is changed. The average flow (pump flow) is constant, the pump flow depends only on the main parameters of the pump, in theory and discharge pressure independent, and with the transport medium temperature, viscosity and other physical and chemical properties have nothing to do, in fact, we should consider the influence of medium leakage. (ZnsdQ*60****) 4/ (2p= (L/h) type: D: column (Live) plug diameter; s: stroke length; N: Reciprocating number; Z: working cylinder number. Pump discharge pressure depends on the characteristics of the pipeline (back pressure and resistance).

8. It has strong adaptability to transportation medium, and can transport high temperature, low temperature, high viscosity, suspension, liquefied gas, etc.. There is good self-priming performance. When the suction height is not too high, the liquid chamber can not pour liquid medium before the pump starts. 3) a safety valve must be installed on the discharge line of the reciprocating pump to ensure that the discharge pressure of the pump is not higher than its rated value. 4) before the start of the reciprocating pump, the exhaust valve must be opened on the pipeline, and the pipeline is not allowed to plug, so as to avoid the pump overpressure, burning motor, pipeline rupture and other accidents. 5) reciprocating pump allows depressurization, does not affect the flow

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