Anhydrous ammonia is a highly efficient refrigerant, provided it remains contaminant free. Contamination reduces the effectiveness of ammonia and can result in higher energy costs, increased wear and tear on expensive refrigeration equipment, and decreased cooling efficiency.

When considering operating costs and capital expenses, maintaining clean ammonia is much like keeping clean oil in your car. Refrigeration accounts for 8 percent of commercial energy use annually in the United States, according to the Department of Energy. Every extra kilowatt-hour used comes off the bottom line.

There are several ways for ammonia to become contaminated. Often, moisture enters into the chiller through leaks in seals, packing and valves, tube ruptures, and condensation during installation. Oil can accumulate from equipment components as well.

Contamination results in increased temperature and energy costs and decreased pump performance, pressure, and evaporator efficiency.

Identifying contamination can prevent serious malfunctions, decrease operating costs, and increase cooling capacity.

One method of determining possible contamination, termed a cold-flow sample, is to draw a small amount of ammonia from the system into a test tube shaped beaker. The flow of ammonia is restricted to a low value by an orifice plate in the inlet line, maintaining atmospheric pressure levels within the tube.

This method, offered by LaRoche Industries, creates an environment within the tube whereby the ammonia can boil under low pressure. The remaining matter in the tube is contamination, which can then be measured. From there - should the contamination levels indicate reduced efficacy - potential resolutions can be considered.

An ammonia service technician can perform the test.

Jodi Crawford is marketing manager for LaRoche Industries and a member of the International Institute of Ammonia Refrigeration. For more information, visit www.larocheind.com.

Publication date: 11/01/2004