Pipe Contamination in NH3 Systems

This morning one of my clients asked me to look into a problem they have found in the ammonia piping. They were noticing a small ammonia smell in a freezer.

Upon inspection they found this flange that was leaking. When they took the flange apart to replace the gasket and inspect the flange, they found the stuff you see in the picture.

I'm still looking into the details for location of this flange, etc. I will post more information as it becomes available.

Has anyone seen anything like this before? This is a new situation I have not seen before.

Copper Oxide?

I know, it's ammonia.....

Why not get it analised. If you've got it in one plece it's probably throughout the system.

Greetings.

I have asked the client if they had it analyzed, but have not had a reply as of yet.

From the appearance in the picture, and since it was found at a leaking joint, I'm wondering if it might be due to minerals from the air borne water entering into the pipe during normal operation.

The system runs in a vaccum during normal operation, so moisture could be drawn in during this time. The water will be absorbed by the ammonia, but the scale could be deposited in the piping at that point.

During defrost, the pressure would be higher, so the leak would travel in the opposite direction and release ammonia.

This is going to be interesting...;)

Ive seen something similar, but in a bubbler tube and drain on a purger, it was calcium and mineral build up from the water and ammonia mixing in the bubbler.

I've seen that before too, but it's been a long time ago. I seem to remember the scale was sort of brown like shown in the picture.

Is that what you remember seeing also?

Thanks for the input.

It looked exactly like the picture, its fresh in my memory due to it happening 2 months ago.

How deep of vacum are they running?

The facility were this happened was ruuninning approx. 10 inchs.

I believe this location is only running about 2-3 inches of vacuum, depending on what is going on.

Over a long period of time I suppose something like this could occur. A vacuum is a vacuum after all.

Looking at it, no idea what it is, but if it is water scale the it hasn't come from the air, airborne moisture contains nothing but air and water. Scale would have to be from a water leak - mains water or cooling loop. Best bet is to get it analysed, not sure if you have anyone in mind as it's not the usual sort of thing for a refrigerant lab. The techinque of choice for thsi would be XRF (X-ray fluorescence), which is common in metallurgical analysis, but a good contract lab should tell you that!

Us Iceman

What is the product they are freezing? Could it be something from that? Is the build up solid or flakey when touched?

Refteach

The picture is all I have to go on right now. This is for a cold storage facility, so nothing fancy.

The contamination in the pipe was described to me as similar to calcium scale on evaporative condensers, or in water pipes.

I'm still waiting on some answers to earlier questions I sent to the client.

Quite interesting, huh?

BTW, why aren't you working?

:p It was close to quiting time.

Try some lime away on a small sample to see if it will disolve? If it does then it points to calcium build up which is unusual to say the least, any idea on H2O content in the system?

Quote:

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Originally Posted by refteach

...any idea on H2O content in the system?

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Not at this time. A lot of details and answers are still unknown.

Let me guess, now it's almost lunch time?:rolleyes:

Quote:

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Originally Posted by US Iceman

From the appearance in the picture, and since it was found at a leaking joint, I'm wondering if it might be due to minerals from the air borne water entering into the pipe during normal operation.

The system runs in a vaccum during normal operation, so moisture could be drawn in during this time. The water will be absorbed by the ammonia, but the scale could be deposited in the piping at that point.

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If it is water, it looks about right to me. If it is "chalky" in consistency, I have seen similar from a leaking condenser tube, hanging as a stalactite from the offending tube. The brown colour could easily be absorbed from rust in the pipe if water was present.

Steve

What I don't know is if this evaporator is water defrost? If so, I think we could make a good case for the junk being scale.

But, I have to agree with Johnny Rod. Testing tells the true story, and I really hate to guess at things.:o

Still waiting on the client for some answer to early questions.

I'll keep you guys posted on future developments. Thanks to all for participating. I appreciate you taking the time to contribute.

Ahhh, that familier blue. the gasket was moist, probably laying around soaking up moisture.
It could also be from the flange itself.
A little "never sieze" goes a long way to stop this.
It does have mass.