Service Hotline: 02/05/2001

February 2, 2001
/ Print / Reprints /
/ Text Size+



From Ted King Alpena, MI

Using a vacuum pump to remove air and moisture, is it necessary to use two tap valves for evacuation? I do, but a lot of service technicians don’t.

I know the cap tube is a small diameter device quite long in length. Can all air and moisture be removed from a low tap only? I’ve read articles that two valves should be applied to remove air and moisture from the entire system.


By John Healy Past International RSES President Colorado Springs, CO

It is most important to use evacuation from both the high and low side at the same time. This method not only saves time, but also is more thorough. Yes, pull a complete vacuum by using two valves pulling from the high and low sides at the same time. It is the only way to completely prepare a system for recharging.

Freezer Fires


From Harold Heffert Bellmore, NY

I remember a question written some time ago about what to do after a freezer fire. My question concerns what precautions could have been taken to prevent the fire and whether adding nitrogen to the system would have prevented the fire.


By Daniel Kramer, P.E. Patent Attorney and former chief engineer for Kramer-Trenton

I think adding nitrogen to the system to prevent what is a rare occurrence is not a good practice. Further, I’m not even sure that adding nitrogen would have prevented the fire. After all, I recall the system you mentioned as having R-404A, which itself is not flammable.

I once encountered a drier that got too hot to hold after it was opened. A drier manufacturer I questioned advised that the flames arose because the aluminum compressor bearings or pistons had been ground into a powder from too much liquid refrigerant floodback into the compressor.

The aluminum in pots and pans is coated with an oxide film. The film prevents any reaction with the air. However, when the aluminum particles reside in the drier, they have not been exposed to oxygen and, therefore, they have no protective oxide film.,p> When the drier is opened, the particles are exposed to the oxygen in the air. The oxidation process they undergo in forming the protective film raises the temperature of the drier.

In your case, maybe there was a felt pad on which the aluminum powder collected, and the oxidation of the aluminum powder raised the temper-ature of the felt pad high enough to cause it to burst into flame.

Publication date: 02/05/2001

You must login or register in order to post a comment.



Image Galleries

2014 Energy Efficiency Forum

Highlights from the 25th annual Energy Efficiency Forum in Washington, D.C.


NEWSMakers: Jason Vogelbaugh

Jason Vogelbaugh of Alpha Controls drops in to the NEWSMakers podcast to discuss his role with the company, the InsideIQ Building Automation Alliance, and current energy-efficiency projects being worked on. Posted on Sept. 26.

More Podcasts


NEWS 09-29-14 cover

2014 September 29

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe


DOE has denied AHRI’s petition for reconsideration of walk-in standards. Is it getting harder to reach consensus on efficiency standards?
View Results Poll Archive


2014 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

Clear Seas Research


Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.


Magazine image
Register today for complete access to ACHRNews.com. Get full access to the latest features, Extra Edition, and more.


facebook icontwitter iconyoutube iconLinkedIn i con