Problems and Solutions
Before I do that, I feel obligated to offer what the lawyers call a disclaimer. This happened a long time ago -- about 30 years ago, well before government agencies started regulating ammonia. I also want to stress that I don't recommend the course of action that was taken. Or, as they say on television, "Don't Try This At Home!" But there is a lesson or two to be learned from this experience.
As I recall, it was a Saturday afternoon around 1 p.m. when the phone rang. On the other end of the line was the voice of a man who was clearly concerned.
"My suction pressure is zero (gauge), but my holding freezer temperature is rising faster than it has for the past couple of weeks. The blast freezer temperature also is high. I just added 5,000 pounds of refrigerant about four weeks ago, so I know there's enough ammonia in the system. So, what do I do now? I have to get the plant operating properly by five o'clock Monday morning, or else!" This was clearly a desperate man -- you'll find out just how desperate in a moment.
We talked for a little longer and came to the conclusion that even though he just had the system topped off with ammonia, the charge could still be the source of his problem. To find out for sure, he drained some oil from the -20 and -40oF (-29 and -40oC) recirculators. When he called me back, low and behold, he found quite a bit of water mixed in with the oil.
Problem identified but not solved. We had to get the water out of the system, and we had to do it quickly. I warned him that to get this done in time, he was probably going to have some midnight work ahead of him because he would likely need to repeat the process several times before all of the water was out of the system. I asked him to give me a call Sunday evening to report on his progress.
Sunday evening came and he called. I was surprised to hear a much happier man on the other end of the phone. "Problem solved," he told me. "The plant is back to normal and everything is working fine!"
I was happy to hear that everything was working fine, but I was also very curious. I asked him, "How in the world did you get the water out of the system so quickly?"
Now, before I tell you his solution, I want to stress again, this is not what you might call a best practice, and if used today, would likely cause major legal headaches with OSHA, EPA and all kinds of other regulatory agencies. "Well," he said, "I dumped the old charge out in my parking lot, and replaced it with a completely new charge of certified refrigeration-grade ammonia. Everything's working just fine."
Water contamination in an ammonia refrigeration system is not an uncommon problem. In fact, it probably happens more often than it should. Once you have experienced it, the problem is fairly easy to recognize in the early stages. That means action can be taken soon enough to avoid the sense of panic that led our friend to do what would be unthinkable -- not to mention illegal -- today.
Preventing this kind of problem -- and correcting it -- is the kind of thing you hear folks talk about at the IIAR Ammonia Refrigeration Conference and Exhibition every year. If the topics aren't covered in a technical paper presentation or panel discussion, there are opportunities to "Chat with an Expert" and a problem/solution session. Or, you can talk with folks out in the hallways and trade war stories. If you have never been to the IIAR Ammonia Refrigeration Conference and Exhibition, you ought to make plans to attend. There are many always-interesting topics in the program. This year, there are presentations on reducing refrigeration energy costs, maintaining product quality while lowering freezing costs, preventing refrigeration system failure, and using natural refrigerants such as ammonia and carbon dioxide. I hope you'll be in Kansas City.
By the way, if you are having a problem with water contamination, check out IIAR Bulletin 108, "Guidelines for Water Contamination in an Ammonia Refri-_geration System." This bulletin offers insight on where the water can come from and how to minimize infiltration into the system. It also has suggestions for quantifying the amounts of water, analyzing the penalties to system performance caused by the water, and removing water in a safe and legal manner, which by the way does not include pumping it onto the nearest vacant parking lot.