How to select a centrifugal pump
Calculation example for the selection of a centrifugal pump
Case A Istallation data
- Q (Flow) = 42 m
3
/h
- Hga (geometric head inlet) = 3,5 m
- Hgp (geometric head outlet) = 39 m
- 5 m DN 100 mm diameter suction pipe complete with 1 elbow
and 1 foot valve
- 70 m DN 80 mm diameter delivery pipe with 1 non-return valve, 1
gate valve and 3 sweep elbows
Hg = Hgp + Hga = 39 + 3,5 = 42,5 m Geometric head of the installa-
tion
A) Operation with suction lift
Hg
Δpc = total head loss
Suction side:
5 m Ø100 piping
1 Elbows
1 Foot valve
Delivery side:
70 m Ø 80 pipe
1 Non-return valve
1 Gate valve
3 Elbows
Total
pc = 0,12 m
pc = 0,045 m
pc = 0,46 m
pc = 5,25 m
pc = 0,5 m
pc = 0,05 m
pc = 0,09 m
Δpc = 6,5 m.
Ø 80 Pipe
70 m Length
4.93.180.1
Ø 100 Pipe
5 m Length
Foot valve
B) Operation under positive suction head
Hg
Hgp
Hga
Considering that the calculation has been made for new pipes, an
increase of 15/20% is to be applied for ageing etc. Therefore the
total head loss Δp amounts to about 8 m.
Therefore, the total manometric head which the pump must achieve is:
Hmt = Hg + Δp = Hgp + Hga + Δpc = 39 + 3,5 + 8 = 50,5 m total.
The pump type NM 50/20AE can be chosen (see pump diagram)
Case B Istallation data
- Q (Flow) = 42 m
3
/h
- Hga (geometric head inlet) = 3,5 m
- Hgp (geometric head outlet) = 39 m
- 5 m DN 100 mm diameter suction pipe complete with 1 gate valve
and 1 foot valve
- 70 m DN 80 mm diameter delivery pipe with 1 non-return valve, 1
gate valve and 3 sweep elbows
Hg = Hgp - Hga = 39 - 3,5 = 35,5 m Geometric head of the installation
Δpc = total head loss
Suction side:
5 m Ø 100 piping
1 Non-return valve
1 Gate valve
Delivery side:
70 m Ø 80 pipe
1 Non-return valve
1 Gate valve
3 Elbows
Total
pc = 0,12 m
pc = 0,5 m
pc = 0,05 m
pc = 5,25 m
pc = 0,5 m
pc = 0,05 m
pc = 0,09 m
Δpc = 6,5 m
Considering that the calculation has been made for new pipes, an
increase of 15/20% is to be applied for ageing etc. Therefore the
total head loss Δpc amount to about 8 m.
Therefore, the total manometric head which the pump must achieve is:
Hmt = Hg + Δp = Hgp - Hga + Δpc = 39 - 3,5 + 8 = 43,5 m total.
Hgp
Hga
Ø 80 Pipe
70 m Length
4.93.100
Ø 100 Pipe
5 m Length
492
