×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Liquid Ring Vacuum Pump Questions
2

Liquid Ring Vacuum Pump Questions

Liquid Ring Vacuum Pump Questions

(OP)
I work in a hospital and we are having problems with our medical vacuum system.

The system is made up of three Beacon MedAes Camel (camel back?) units with Nash liquid ring vacuum pumps.

My first question is about the water supply. We are using unsoftened city water and in a short period of time all three pumps have frozen up and we have had to de-scale the pumps using Rydlyme.

Last night we installed a Descalamatic to help with the water hardness issues. Is this the right application for a Descalamatic?
Do they work as advertised?

Currently pump 3 is timing out and going into alarm. This happens right before they freeze up. There is a fitting on the inlet side of the pump that looks like a relief valve. It has holes at the bottom and when the pump is activated it starts sucking air. The same fitting on pump 2 is starting to do the same.

What is the purpose of the fitting and is the air intake related to the scale build up in the pumps?

As you can tell I'm not an expert on these pumps and any troubleshooting and maintenance info would be greatly appreciated.




 

RE: Liquid Ring Vacuum Pump Questions

Go to NASH for technical info on these.
They have good info.
You need good quality water that is as cold as possible.
 

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

RE: Liquid Ring Vacuum Pump Questions

No, the Descalamatic.com "magnetic descaler" will not affect deposits left by evaporating water in a vacuum pump.  Anybody telling you it will needs to explain where the calcium/magnesium oxide/carbonate go when the water evaporates.

RE: Liquid Ring Vacuum Pump Questions

(OP)
That was my initial thought on the Descalamatic. There is no substitute for soft water. I had customers use other types of magnets on their dish washing machines and they never worked.
I thought this might be different.

 

RE: Liquid Ring Vacuum Pump Questions

Check with NASH first.  Find their local rep.

You'll need softened water that is cold, as stated above.

Is it possible to replace these pumps? I've only used a few liquid ring pumps, and I never had them sucking air from a housing fitting.

How much vacuum do you need to pull? How often..? What kind of loading?

RE: Liquid Ring Vacuum Pump Questions

(OP)
Thanks for the link bimr. It confirms my suspicions in a language I don't uderstand!

The bottom line is that the devices tested did not work as advertised. I'll forward the link to our CE. Hopefully this will lead to us installing a real water softener, filters and a pressure regulator.  

Pump 3 froze up again two nights ago leaving us with two pumps that have to be scaling up as we speak.

Ports, if it was up to me we would have had a Nash rep on site a long time ago. It looks like short term savings is winning out over long term savings.

We maintain 22" with set points of 19" and 24".  The pumps cycle continuously with roughly a five to six minute run time. As soon as a pump shuts off it takes about two minutes for the vacuum to reach the 19" set point.   

RE: Liquid Ring Vacuum Pump Questions

2
Do you have of your process water blowing down to a drain? Water in liquid ring pumps evaporates rapidly and minerals will concentrate until they precipitate. You can't simply add water without draining some also.

RE: Liquid Ring Vacuum Pump Questions

Compositepro,

When I used a liquid ring pump, we did a once through on it.. all of the water went straight through to the drain. *Research is wasteful.

In his case.. are they recycling the water back to a tank, and you're thinking of a flush cycle or blowdown on that tank?

RE: Liquid Ring Vacuum Pump Questions

Some liquid leaves the pump with the gas. This is usually captured and recirculated. Some of the liquid also evaporates in the pump. As you point out, the liquid need not be recirculated, and this blowdown to drain will prevent mineral build-up. But using no recirculation will also usually result in an unnecessarily high water useage. Total recirculation is easy to achieve but will eventually ruin the pump.  

RE: Liquid Ring Vacuum Pump Questions

Composite, well then, if he can talk them into spending the money.  I'd think they'd be better off with a small oil vacuum pump. A Busch or an Edwards.

RE: Liquid Ring Vacuum Pump Questions

Perhaps, but the application is a hospital. So uses probably include suctioning body fluids. These should be trapped before getting into the piping but the vapor flow will be high volume, dirty, and not deep vacuum. That's a good application for a liquid ring pump.

RE: Liquid Ring Vacuum Pump Questions

(OP)
An update on the liquid ring pumps if anyone is interested.
Pump 2 froze up several weeks ago and the powers that be decided to rent a Busch just like ports suggested.

Last I heard they were getting bids on replacing all three pumps with Busch pumps.

 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources