This is not the first time I have written about “limitations” of our emergency response equipment, but this is one I just learned first hand. Let me be CLEAR HERE… ALL equipment and gear we use has limitations so this is not any type of slam against any manufacturer – in fact the piece of equipment I will be discussing in this article can be found just about every HAZMAT vehicle in the USA and it works like a charm, as long as we use it within its LIMITATION(s).
So here is the scene:
Workers reported the smell of ammonia around a -35 degree freezer. Refrigeration techs investigated and could smell the NH3 as well. A puddle was located within the freezer and unfortunately the production workers were not adequately trained in NH3 and its behaviors and hazards and figured the puddle was water (keep in mind this is a -35F freezer!). But to compound the problem, the refrigeration techs brought in a colorimetric tube to test the atmosphere within the freezer to establish what the puddle was.
Assuming it was ammonia, they brought their ammonia tubes for the test(s). Each test resulted NO readings, yet the odor was still present and it seemed to be increasing in intensity. However, the team was puzzled as to why the tubes showed ZERO in the presence of such a strong odor. The facility was without any other type monitor to get a second sample/opinion. At this point the local FD was called for assistance. Once they got within 20’ of the puddled material their direct reading instrument began to register ammonia in the atmosphere. The puddle’s pH was tested as a secondary means of identification and it was determined to be ammonia.
In their investigation, the facility contacted us to help understand why their colorimetric tube(s) failed them. The first thing we asked about was the “expiration date” of the tubes – YES these tubes EXPIRE. But in this case, the evidence showed that the tubes had been stored properly and were NOT expired. So I went to the data sheet for the tubes and found that the ammonia tubes with a detection range of 50-900 ppm do NOT work in environments below 32F. Which is quite amazing seeing how many of these Colorimetric tubes are used in refrigeration plants. So using them in a freezer that is operating at -35F would explain why they failed to operate.
So this was news to me, so I began to check other tubes for some of the more common chemicals and found that ALL of the tubes have a working temperature range of 0-40C (32-104F).
Ammonia = 0-40C
Chlorine = 0-40C
Sulfuric Acid = 5-40C
HF = 0-40C
So if you use these colorimetric tubes, remember they do not function properly when the temperature they are being used in is below 32F (0C).