liquid ring pump locked up!

[mec5216]

Hello!

In the process plant I work, we have a NASH luquid ring vacuum pump. It was working very well, until it suddenly locked up. We have been told by the operators that the pump operated for some time with no sealing luquid.
When we opend the pump to see what was going on, we found that the wear between the left cone and the rotor had been so intense that these two pieces were welded together.
My question is if this lack of sealing liquid was the only or main cause for the problem. I'm saying that because the sealing liquid has no function of lubricating or cooling the movable parts of the pump, its only function is to work as a piston, suctioning and discharging the gas.

Thanks!

 

[MikeHalloran]

I don't think you're gettng the full story from the operators. ... but yes, the pump should be able to run indefinitely with no sealing liquid flow. ... during which time it won't pump squat, so a change in the process should make it noticeable, or the seal liquid supply should have a flow or pressure switch connected to an alarm.



Mike Halloran
Pembroke Pines, FL, USA

 

[ccfowler]

I recommend that you pay very close attention to all of the details, and be cautious of dismissing possibilities too early in your evaluation of the whole situation. In my experience, nearly every burned up bearing has happened while associated with an oil reservoir that was full to the proper level of cool, clean lube oil of the correct type, if one could accept the obvious physical evidence at the site. Sometimes, lubrication wasn't the actual problem, but the cool, clean lube oil was almost certain to be found anyway, "just in case."

In your situation, I would want to pay very close attention to the possibilities involving alignments or excessive bearing loadings. Something happened that allowed parts to come into contact where no contact should have been able to occur.

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.

 

[Artisi]

a few photo's might well go a long way in sorting out some constructive feedback.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[mec5216]

Actually this loss of vacuum in the process is not noticed immediatley by the operators. But it's already been studied the possibility of installing a switch pressure connected to the alarm.
What we could see up to this moment in disassembling the equipment, is that bearing house from both sides shown marks of excessive looseness and eccentricity. As well, there was an excessive number of gaskets between the housing and the head of the pump in both sides.
Theses are the facts observed up to now, and that I think that have contribuited a lot to the problem of the pump.

Below there are some photos I took, including the are of contact between the rotor and the cone.

 

[mec5216]

photo

 

[mec5216]

photo of the rotor attached to the cone

 

[mec5216]

bearing house showing wear pattern