By Kem Russell

Participating in IIAR conferences, webinars, committees, and sub-committees has certainly increased my knowledge and my access to information. I have listened to and worked with very knowledgeable people from many backgrounds. Even after being involved in the ammonia refrigeration industry, and specifically IIAR for many decades, I am still learning. This reminds me of a famous statement I read in a book by Donald Rumsfeld, who served as George W. Bush’s secretary of defense.

Rumsfeld said: “As we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say, we know there are some things we do not know. But there are also unknown unknowns—the ones we don’t know we don’t know.”

The part of this quote that still surprises me today is how many times I experience “unknown unknowns.” I am not going to get into the details of some of the “unknown unknowns” that I have run into, but generally describe three examples of things I recently “didn’t know I didn’t know.”

In doing maintenance of ammonia equipment and piping one primary concern is that the work is done safely. A lot of thought has gone into what should be done to be safe, yet still, be able to perform the intended activity.

One example, where I have been surprised at what I didn’t know, is entering an evaporative condenser. I have been inside of many evaporative condensers. Before entering a unit certain precautions are taken, such as verifying that the fans and water pump(s) have been shut down and locked out; and visually looking inside the unit for possible interior hazards. Before I knew of such a thing as Legionnaires’ disease, I, and everyone I knew, just went inside the condenser. I have not heard of someone catching Legionnaires’ disease from entering an evaporative condenser, but it does seem to be a potential area that could have the bacteria. Now wearing some type of breathing protection seems like good advice.

Does the interior of an evaporative condenser qualify as a confined space? I didn’t really give this much thought, however in conversations with knowledgeable people on this topic, evaporative condensers do fit the requirement of a “Permit Required Confined Space” (PRCS). As I mentioned, decades ago I never saw an evaporative condenser with signage identifying the space as a “Confined Space.” It wasn’t until about the last 10 – 15 years that I started seeing some units with a sign, and the few I saw had a sign saying something like, “No-permit required Confined Space”, which from what I have understood would not be appropriate signage.

If the interior of a condenser is PRCS, what does that mean? Here I have run into “unknown unknowns”, and this issue is still being discussed by knowledgeable people participating in the IIAR Safety Committee. One of the challenges with entering an evaporative condenser is the ammonia in the coil. If there is even a “potential” of a release of a hazardous substance, then certain actions, according to OSHA, must be taken. The ammonia must be removed from the coil. That’s easier said than done, but assume there is a safe way to do that. The next hurdle is isolation of the coil from the system. There are three methods for doing this, however, no evaporative condenser installation I have seen can be isolated using one of those methods. How we match up what we have (design and procedures) with what the OSHA regulations apparently require, is a challenge. Hopefully, over the next several months, a reasonable recommended approach will be determined.

Another example:
Air purifying respirators. Early in my ammonia refrigeration career, I was at times assigned to assist a refrigeration technician as work was done changing piping and control valves on an active ammonia system. During the 1960’s I had no knowledge of PPM levels, I just knew ammonia made my eyes water, breathing difficult, and I wanted to leave the space. However, when ammonia became too irritating we wore a canister style full-face respirator, the kind with the elephant hose from the mask to the canister. I also did not know there was such a thing as “fit testing”, nor did the people I worked with. All we knew at the time was that if the face seal was good, we didn’t experience effects on our eyes or breathing due to the ammonia.

At that time I didn’t know there might be devices that could measure the PPM of the ammonia. I’m not sure that such measuring devices were even generally available to purchase. What PPM levels we were working in was unknown. We now know the levels should be measured and monitored. It was also not known that ammonia within a fairly narrow range of concentrations in air, and in an enclosed space could possibly ignite. We now know this. I did see flames erupt out of cut lines, but at the time we thought that was just the residual oil, not realizing that ammonia vapor might have been part of the flaming action. We also heard some scary sounds inside of a few pressure vessels. All the time doing work I know I was never in a concentration that was high enough to result in a possible ignition. I was never in a hazy ammonia atmosphere, but this was due to luck, not knowledge. At the time the only testing means we had was that if you started to feel stinging it was time to leave.

Even if you didn’t feel stinging, the canister would eventually reach a saturation level (you started smelling ammonia in the mask), which told you it was time to change the canister. As time has gone by, more and more people started using cartridge-style instead of canister-style full-faced ammonia masks. Presently a large percentage of air purifying respirator (APR) masks are cartridge style. What I didn’t know until fairly recently is there is a difference in the specifications NIOSH uses for masks. A cartridge-style meets the specifications for a 23C, which is good for PPM levels up to, but not over 300 PPM, the IDLH for ammonia. The canister-style mask is a 14G, which is also good for 300 PPM. However, while wearing the 14G a person could accidentally be in a higher PPM level due to a sudden release and they can justifiably escape, they just cannot go back in the above 300 PPM environment. So, with the 23C a person never goes above 300 PPM, but with a 14G style, you could be above 300 PPM and escape. This for me was an unknown unknown, and I am still studying this one.

One more example of an unknown is a term I never thought of that now applies to something I know a fair amount about, which is ammonia. I have seen liquid ammonia many times. If you were upwind and the pool has stabilized, you might first think it was water. After the first few seconds, you should notice visible vapor forming and disappearing just above the liquid surface, like wisps of smoke. Ammonia is a clear and very cold liquid at atmospheric pressure.

Not too many months ago, while on a conference call I heard the term “Green ammonia.” What is that? Even though I am Red/Green colorblind, I know ammonia is most often clear (other impurities such as oils, etc. might change the color). The term actually doesn’t apply to the color, but to the energy source used to produce it. In this case, ammonia is being produced using solar or wind power generating methods. Thus ammonia is called green because it’s being produced using a renewable energy source.

There are many unknowns, and even unknown unknowns, even within our industrial ammonia refrigeration industry. As we stay involved, listen, and learn, we can, over time, change many of these unknowns into knowns, which can improve designs, operation and maintenance, and overall safety for all.