Liquid Ring Vacuum Pump Questions 2

[raunchhand]

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.

 

[EdStainless]

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


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Plymouth Tube

 

[btrueblood]

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.

 

[raunchhand]

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.

 

[ports394]

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?

 

[bimr]

The descalamatic device is a gadget sold by deluded inventors and will basically do nothing. The US Army did a report on this particular gadget that scientifically proved it did not work.

http://www.culligan.com/uploadedFil..._Free_Solutions/Army Corps_pwtb_420_49_34.pdf

The fitting is either an anti-cavitation valve or an automatic drain valve.

 

[raunchhand]

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.

 

[Compositepro]

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.

 

[ports394]

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?

 

[Compositepro]

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.

 

[ports394]

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.

 

[Compositepro]

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.

 

[justabitconfused]

The device you describe could be an ejector on the liquid ring pump, used to help increase the vacuum you can pull on the unit. See here for an explanation of how it works

http://innoleague.com/How to increase Vacuum of LR Vac Pump.pdf.

 

[raunchhand]

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.