Spirax Sarco - Catalogo Agosto 2017

Condensate pumps

Mechanical pumps and pumps traps

Page 4 of 6

Plant

1500 kg/h

Reservoir

Filling head

metres (m)

Capacity multiplying factors

DN25

DN40

DN50

DN80 x DN50

0.15

0.90

0.75

0.80

0.30

1.00

0.60

1.15

1.10

1.20

1.05

0.90

1.35

1.25

1.30

1.15

6.1.17

Pump

size

% Backpressure Vs Motive pressure (BP/MP)

10%

20%

30%

40%

50%

60%

70%

80%

90%

Capacity multiplying factors

DN25

1.20

1.25

1.30

1.35

1.40

1.43

1.46

1.50

1.53

DN40

1.20

1.25

1.30

1.35

1.40

1.43

1.46

1.50

1.53

DN50

1.02

1.05

1.08

1.10

1.15

1.20

1.27

1.33

1.40

DN80 x DN50

1.02

1.05

1.08

1.10

1.15

1.20

1.27

1.33

1.40

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.

How to use the sizing chart

= 1.7barg

Return main

pressure and

pipe length

Operating

pressure

5.2 barg

Condensate load

Steam pressure available for operating pump

Vertical lift from pump to the return piping

Pressure in the return piping (piping friction negligible)

Filling head on the pump available

Lift = 9.2m

1500kg/h

5.2 bar g

9.2 m

1.7 bar g

0.15 m

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Example

DN50 pump capacities

0.15 m

Filling head

MFP14

The known data

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:-

= 1.7 bar g ÷ 0.0981 = 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 5.

1. Plot a horizontal line from 5.2 bar g (Motive pressure).

2. Plot a line indicating 26.5 m lift.

3. Fromthepointwherethemotivepressurelinecrosses

the m lift line, drop a vertical line to the X axis.

4. Read the corresponding capacity (2 400 kg / h).

Note: As the filling head is different to 0.3 m, then the capacity

calculated above must be corrected by the appropriate factor

selected from the table opposite.

Capacity multiplying factors for other filling heads

For motive fluids other than steam, see the table below.

Final pump selection

The size of pump selected in this case would be DN50.

This has the capability to pump:-

0.75 x 2400 kg/h = 1800 kg/h

easily coping with a condensate load of 1500 kg/h.

Note: If the motive fluid is not steam, then the capacity above must

be multiplied by the appropriate factor in the table below.

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Flowrate kg/h

Capacity multiplying factors for motive gas supplies (other than steam)

MFP14, MFP14S and MFP14SS Automatic Pumps

TI-P136-02 ST Issue 12

Page 4 of 6

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