An Experienced New Choice in Industrial Refrigeration. Superior Industrial Refrigeration (SIR) is a licensed industrial refrigeration contractor installing ammonia (NH3) systems, serving ID, UT, WA, OR, MT, & AK. We specialize in designing and installing large and small refrigeration construction projects, replacement parts, emergency or scheduled service & maintenance calls, and compressor rebuilds and retrofits. SIR is safety focused, offering HAZWOPER training events.