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Temperature pressure checks on ammonia freezing systems

By Alison Basista

I learned about the Fluke 52 II Digital Thermometer from a contractor, who could test the liquid drop ammonia to check the accuracy of the digital controller. I bought one so that I would be able to regularly check the freezing system and ensure proper functionality. As it turned out, we had a short in one of the wires and so the control screen was not actually reading the correct temperature of the unit. To make the measurement, I just touch the outside of the pipe with the probe attachment. This reads the temperature, which, depending on other factors, should be about 80°F. Variations in the temperature, in conjunction with the pressure readings on the gauge, alert you to possible issues, such as air in the lines, which is a very bad thing for an ammonia system. There are standard temperature/pressure charts that tell you what to expect. Extreme variations from that norm alert you to issues and then it is a matter of identifying what that issue is. But without being able to measure the temperatures and compare to the electric gauges or PLC systems, there's no real way to know you have an issue until it's too late. Currently, I check the system reading against the Fluke reading once a week.