An effective preventive maintenance program should always include regularly scheduled analysis of heat transfer fluids.
There are two steps to the thermal-fluid analysis process. The first is observational, the second is analytical.
Paratherm’s trained technicians can open up the jar and observe a thermal fluid sample, using three of the five senses (generally, we don’t taste it, or listen to it) and a few simple empirical techniques, to record viscosity, consistency, water contamination, metal contamination, and possible acidity, particle formation, and presence of sludge.
These objective observations can tell us much about the fluid. Often, suspicions of contamination arise during this step, and can be confirmed by the subsequent lab tests. Appearance and odor can indicate contamination, as well as possible cracking due to overheating, and increased acidity due to oxidation.
If we observe metal contamination, we can diagnose metallic wear in the system; most often due to pump problems, but also sometimes originating elsewhere. (story continues below…)
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If we observe water contamination, we can interview the system engineer to determine possible exchanger breaches, or other system problems that can introduce moisture to the circuit.
When the preliminary observations are complete, the sample is sent to the laboratory to be tested for TAN (Total Acid Number,) kinematic viscosity, and distillation range.
On the laboratory end, changes in the distillation curve can indicate overheating problems, as can viscosity changes. We compare the new-fluid values for these parameters with those of the sample from the working system. Interviewing the system operators can then help us pinpoint whether there are fluid velocity problems, flow restrictions, expansion tank configurations, or other system characteristics that may be causing overheating.
In a similar manner, when the total acid number of the fluid has exceeded the envelope we consider optimum, we can work with the customer to help determine how their system is malfunctioning, or underfunctioning, to cause air to contact the hot fluid and oxidize it.
