Liquid Ring in Vacuum Pump

Yes, too much water is a good explanantion for a high power absorbed and a motor overload.

This is due to the excessive pressure drop at the discharge port , where the gas and the seal liquid (water) are coming out of the pump. Pumps with a conical distributor (Nash or Cutes design) have larger ports (larger than with flat sided distributors) and the "conical"-pumps will be able to "digest" more water.

If you need more seal water than the pump is able to handle (because of an high heat load, condensation of vapours,..) then use a precondenser and reduce the seal water flow.

Hope it helps, PS, www.cutes-europe.com

Refer the figure, indicated as 'R', the thickness of the liquid ring is proportional to the power consumed.

The right amount of liquid required for optimum performance is normally controlled by orifice, either located outside or inside the machine.

These are mostly of fixed size and shape from manufacturer to manufacturer. If the effective orifice dia (opening) enlarges due to corrosion and erosion, there is a tendency for more liquid in circulation.

Investigate on these line and restore the original size of the orifice and established the required amount of liquid inside the machine.

Have you checked to see if the pump has developed scale around the casing or impellor?

In some instances, if the condensor is run at a higher temp, then scale can be formed if the sealing water is too hard.

Hi Mzreeb,

I do not think that you can have 'excessive' seal water in the vacuum pump casing inside. By its characteristics, any excessive will be discharged by the centrifugal force of the impeller. And actually, that is the fundamental of operation of vacuum ring pump.

If the motor tripped repeatedly, I would like to suggest to check the followings.

Some of them could be already checked by you.

1. Check your currency meter. Is it checking the currency correctly? Sometimes mere malfunctioning of currency meter causes tripping of the important machine. This is to identify whether your trip is real trip by the overloading or not.

2. If it is the real trip, check the casing inside and confirm there is no damage, scale, erosion nor corrosion. There could be damage or error on assembly which can allow more water to be induced inside the casing.

3. Why is the motor problem always free from the responsibility when the trip is arose? If you do not find any suspicious while checking 1 and 2, then motor can be the matter. Is it brand new motor or very old motor. Does its noise sould normal or not. Bearing trouble sometimes causes the overload and trip.

All these ideas are based on the fact that there is no change in process condition!!

No change in Gas, No change in suction and discharge condition, No change in temperature!!!

I hope this will be helpful for you... Thanks!!