explain the procedure please.

Here is the answer I gave to another question on centrifugal pump startup. The only difference with a canned pump is the fact that they tend to be much easier to prime due to their geometry.

Assuming the pump is properly primed, The main considerations in starting up a centrifugal pump is the suction and discharge systems, the presence or absence of a check valve in the discharge and its condition as well as the pressure capability of the two systems.

A pump may be pumping against no discharge pressure or it may be pumping against an existing pressure. In the case of no pressure, you need to have the discharge valve closed otherwise you may overload the driver.

If there is existing pressure in the discharge line, there is no concern with over loading either the pump or driver on start up since the pump develops no load until it starts to rotate and build head. If there is a check valve in the discharge and the block valve is open, there is essentially no flow (and therefore no load) until the head developed exceeds the pressure in the discharge line.

The real consideration is having back flow from the discharge to the suction. That is the reason for a properly selected check valve that is properly maintained so it will function as designed. In the case of high pressure pumps where the discharge pressure can exceed the suction pressure to the extent that the suction system could fail it is very important that either the pump be started with the discharge closed or with a properly operating check valve.

One should note that if the pump is multistage, there may be a minimum flow requirement that needs to be worked into the start up procedure to assure there is minimum flow established as soon as possible.

I would assume the only consideration in starting a vacuum pump is the question of maintaining an existing vacuum. In that case you would need as a minimum a check valve in the line to prevent back flow and the loss of the vacuum. Otherwise starting should be similar to starting a centrifugal pump. The final consideration being concern for not overloading the driver on initial startup.

in past it is impossible but i wanna know that in these days there are it?

1. #Any centrifugal pump can not handle gases with liquids.
2. Please learn about priming of centrifugal pumps.
3. #Suppose a centrifugal pump is running on 2900 RPM and if you want to run it for expelling gases, you have to run the pump at a speed of [2900*800] RPM that is practically impossible.
4. # only regenerative turbine pumps can handle little amount of vapours upto some extent .But these pumps are not purely centrifugal as there are two actions while pumping:
5. centrifugal and shearing action.
6. # Go through the following link and understand that self priming pump also needs priming:http://www.otspumps.com/products/PDFmanu…

The power is proportional to the cube of the pump speed.

You will need to create the pump curves for your pump, or the vendor may have one you can use, or adapt to your fluid with a density coefficient.

http://www.engineersedge.com/fluid_flow/

We have two series connected 2.2 kw (3HP) centrifugal pumps used for domestic water supply from ground floor to over head tank at 25 m high. Delivery line has 100 mm dia. reduced to 40 mm dia. GI pipe If we change the 40 mm dia. GI pipe to 75 mm dia. GI or PVC pipe, will there be any saving on pumping time?

Yes, a turbine pump is centrifugal pump because the amount of fluid that is displaced depends on the resistance of the existing piping system (given a constant speed).

A positive displacement pump is going to have a fixed volumetric displacement for a given speed.

Really what I think you mean when you say “turbine pump” is a turbine driven centrifugal pump. In other words a high energy pump, like a boiler feed water pump.

Why did it heat up?
Estimate how many degrees F per hour the water heated up and explain your reasoning.

Can we calculate it for reciprocating pumps also? if yes, how? Is there any thumb rule for this?

I would like how is the pump’s suction head related to its operational head? or discharge head? or on its performance…