VS4 Pumps - Shaft Length Limitation

There is no specific limitation, there are however practical limitations. When you say shaft length, do you mean the overall length from coupling to end of shaft, or the distance from top of pit (mounting plate) to impeller centre line? If the latter then around 2.1 maybe 2.3 meters is about maximum, though some OEM's go longer. I get twitchy around 1.8 meters. There are practical limitations on shaft diameter depending on power input, product characteristics etc. Temperature and expansion need to be considered. As you get longer you need thicker shafts and bigger bearings. Eventually the cost is just not worth it and you need another solution. Go with the OEM limits, but even then be aware that OEM's are a bit optimistic so be conservative if you want long service life.

If you are considering a VS4 pump then it is not a cantilever type. The API designation for a vertical cantilever pump is a VS5. With regard to a VS4 pump the practical maximum length is around 10 metres depending on the size and weight of the pump and motor combination. If you require further data please visit www.amarinth.com.

Can't do the smiley thing from gmail, but the embarrased one would do. Took cantilever at face value and did not even think to look up the API number.

The Shaft Lenght for VS4 is limited because of the vibration and torsion, it will increase the wear of bearings and reduce the service life of the components. That is the reason why Vendors commonly sell VS4 Pumps with shafts not longer than 2.0 meters. Usually this kind of pumps are used in Sumps and work automatically, it means: it starts when the level in the sump is over the High level and stops when the level is above the Low. Then if it is not necessary to work with this system you can use a submersible pump and you will not worried about the shaft lenght.

The VS4 pumps are particularly suited to oil production drains duties where there is a mixture of water and various oil fractions sometimes including sour gas and CO2. As the pump does not require a mechanical seal to operate it has an advantage over electro-submersible pumps which require a double seal system.

JUST FOR YOUR INFO. WE HAVE A VS4 pump mounted on vessel with Mech seal.

API 682 Seal Code: C2A1A0261 Gas Seal.

Fluid is - 99.9% minimum Tri-ethylene Glycol (TEG)

I'm sorry I didn't mean to mislead what I meant is that a seal is not needed for the pumps hydraulic performance. However a seal can be fitted at the pumps top plate to prevent leakage of vapour from the tank the pump is mounted in. It is therefore possible to maintain the seal without having to remove the pump from the tank.