Multistage Pump
Multistage Pump
A multistage pump is a type of pump which contains 2 or more impellers which may be of the same or different types i.e low NPSH suction impeller, double suction impeller or combination with Centrifugal first stage and side channel stage impellers.
What are the multi stage pump parts?
The multistage pump parts are very similar to those of the standard Centrifugal pump except for the Multistage Centrifugal pump where the additional parts are diffusers which efficiently channel the fluid into the eye of the impeller or to the following stage. In the side channel pump, there are intermediate plates with the scalloped side channel and liquid parts.
In multistage centrifugal pumps, because of the high thrust that is generated due to the impellers facing in the same direction, there will be a thrust balance device i.e balance disc or balance drum which reduces the thrust to a level which can be managed by a standard sized thrust bearing.
How does a multi stage pump work?
A multistage pump operates by one impeller feeding into the next impeller and the number of impellers required depend on the discharge pressure requirement. Liquid enters the pump and then passes through the various number of impellers in a sequence from the left to right.
What are the applications and uses for multi stage pumps?
The applications for multi stage pumps are many and varied and can be used for delivering water to high rise buildings, reverse osmosis (RO), boiler feed water, spraying, high pressure cleaning, water works, heating, condensate, fuel delivery, oil and gas production, power generation & mining and other high pressure and temperature applications..
What are the different types of multi stage pumps?
Types of multistage pumps include;
What are the advantages of using a multi stage pump?
If we were to compare the Centrifugal multi stage pump to a high pressure duty pump – the Centrifugal multi stage pump even though it is more complex and costly, it would probably be a better hydraulic fit, have a better efficiency and be more reliable. With its hydraulic modules, the ability to supply additional impellers and its ability to trim those impellers, the duty point can me met exactly without compromise. The selection is more likely to be close to ‘BEP’ and will run efficiently and reliably.
Multi stage pumps can be configured to have an interstage bleed off if there are multiple duty points required. It may be possible to run a multistage pump at a lower speed than a single stage centrifugal pump which may offer an efficiency advantage but it will certainly run much quieter which is an important consideration in today’s world. A 3 dBA increase represents a doubling of sound as the sound scale is logarithmic.
What is difference between a single stage and a multi stage pump?
A single stage pump uses one impeller whereas a multi stage pump uses 2 or more impellers (some manufacturers use 80 or more impellers).
There are additional components in a multi stage pump which are required for channelling the fluid from the first stage to the following stage i.e diffusers.
Multi stage pumps have a thrust balance device and there may also be intermediate bearings (lubricated by the pumpage) to steady the shaft plus other minor differences.
How do you read a multistage pump curve?
You read a multi stage pump curve in exactly the same way as you read any other pump type curve however some manufacturers will publish single stage curves which means that this has to be multiplied out to establish the number of stages required, however be aware that the side channel pumps have their maximum power at zero flow and the power decreases with increasing flow which is the reverse of a centrifugal pump.
