How to size and select Considering the inlet pressure, backpressure and filling head conditions, select the pump size which meets the capacity requirements of the application. Condensate pumps Mechanical pumps and pumps traps
9
How to use the sizing chart
P 2 = 1.7bar g Return main pressure and pipe length
Plant 1500 kg/h
Reservoir
Operating pressure 5.2bar g
Lift = 9.2m
0.3m Filling head
MFP14
The known data
Condensate load 1500 kg/h Steam pressure available for operating pump 5.2 bar g Vertical lift from pump to the return piping 9.2 m Pressure in the return piping (piping friction negligible) 1.7 bar g Filling head on the pump available 0.3 m
Flowrate kg/h
Example DN50 pump capacities
Note: It is strongly recommended that the maximum motive / backpressure differential is between 2 - 4 bar g.
Selection example Firstly calculate the total effective lift against which condensate must be pumped. Total effective lift is calculated by adding vertical lift from the pump to return piping (9.2 m) to the pressure in the return piping (1.7 bar g). To convert pressure in the return pipe into pressure head, divide it by the conversion factor of 0.0981:- P 2 = 1.7 bar g ÷ 0.098 1 = 17.3 m Pressure head (lift) The total effective lift then becomes calculable :- 9.2 m + 17.3 m The total effective lift is 26.5 m Now that the total effective lift has been calculated, a pump can be selected by plotting the known data onto the graphs on page 9. 1. Plot a horizontal line from 5.2 bar g (Motive pressure). 2. Plot a line indicating 26.5 m lift. 3. From the point where the motive pressure line crosses the m lift line, drop a vertical line to the X axis. 4. Read the corresponding capacity (2400 kg/h). The capacity charts shown are for single pumps. The capacities should be doubled or tripled to give the capacities of the duplex or triplex pumped packages. Note: The MFP14-PPU packages are not supplied with a connecting condensate return manifold. Ideally each pump should have its own dedicated return line to a vented receiver or holding tank. If the duplex pump returns are to be joined together to create a collective return line, care should be taken to ensure that it is adequately sized to accommodate the instantaneous discharge rate of all pumps discharging at the same time. Failure to do this may result in reduced capacity of the packaged pump unit.
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TI-P681-01 CMGT Issue 6
Page 12 of 14
MFP14-PPU (Vented) Automatic Pump Packaged Units
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