Ammonia vs other refrigerants

[Wilson1977]

Hi people,

I've been asked to look at a site that has large ammonia equipment. Having been in the trade for 20 years I've worked on most things except ammonia! What are the main things to take into account and the differences to other refrigerants? I understand that I need to get 2078 part 3 & 4 to add to my fgas 2079, so that'll be my next move. Any advice on this would be greatly appreciated.

Thanks

[RANGER1]

Wilson,
Pretty open question to answer, but here's a few things even though were only guessing what your plant may be.

Probably no TX valves, as most systems use liquid overfeed & hand expansion valves.
You may see vessels with liquid pumps on the bottom of them pumping ammonia out to the rooms etc.

A small leak & everyone will tell you about it if you don't know.

You have to be think ahead of any situation if servicing equipment or breaking into system.
Ammonia there is no second chances to mistakes.

Ammonia is slow to evaporate unlike other refrigerant. It needs heat, so pumping things out takes longer
to empty things out of strainers, low spots etc.

[Wilson1977]

Hi Ranger1,

The plant installed is 3 x Grasso RC612 compressors and 3 x Grasso RC4212 compressors serving freezer coldroom and chiller coldroom. Various other components are evaporative condensers, valve stations, surge drums, liquid pumps, intercooler. I'm going to have a site visit soon to have a look! I would class myself as pretty adaptable to things I havent worked on but are the differences in operation very different? When you say no second chances, in what respect?

Thanks for the response

[mrfreezeit]

Might take a look at RETA publications. They have a basic manual called "Ammonia What you don't know can and will hurt you."

Sounds like a 2 stage system with liquid recirc. Surge drums may be for a flooded system, unless the vessels were mistaken as surge drums instead of the recirculation vessel for the pumps.
Ammonia is deadly in 8 min at 5,000ppm. At 300ppm it can have escape impairing characteristics. 10-25ppm will probably be uncomfortable for you. Ammonia is dangerous, it is 99.98% pure or better. Floor cleaner is like 3%. As low as 10% levels, when mixed with refrigerant oil (with recips, there will be), it can be explosive and deflagrate (same as detonate only subsonic). 1# or .45kg of liquid ammonia can expand to 227ft3 or 6.5m3 of vapor. -28F or -33C coming out of the pipe can cause some nasty burns. Pros - leaks are detectable by your nose as low as 1-5ppm. BE CAREFUL.

[coolman]

rule off thumb when working with ammonia.
do not shave, make sure there are no small wound on hands, arms and face, work slow so you will not transpirate