Ammonia is one of the best known and most widely used refrigerants in use today for ice plants, food lockers, cold storage warehouses and other industrial cooling processes. It has a higher refrigerating effect, per unit of liquid volume, than any other type of commonly used refrigerant. Other advantages are low initial cost, low pipe friction losses, zero ODP (Ozone Depletion Potential) and zero GWP (Global Warming Potential). With the recent trend of environmental awareness in the refrigeration industry, natural refrigerants like ammonia are even more desirable.
Over the years, Viking has gained considerable experience with handling ammonia in refrigeration systems and designing pumps for this specific liquid. Ammonia, a high vapor pressure liquid, has to be kept in a closed container to keep it from boiling away. For typical ammonia applications, we suggest the double-seal Viking pump 4924A series, with the materials and specifications shown below, to ensure a safe and controlled way of pumping refrigerants.
First and foremost, we advise having a pressure relief device in any part of an ammonia pump and piping system that can be “valved” off. This provides essential over-pressure protection, as cold liquid ammonia when isolated will expand as it warms up and exert pressures that could rupture the pump or piping unless relieved.
- Return-to-tank pressure relief valves should be mounted on the discharge side of the pump.
- Internal type pressure relief valves should be mounted with the cap pointing towards the suction side of the pump.
The installation of the pump, itself, on any refrigeration system is also critical to prevent such hazards from occurring. For example, sufficient head (at least 4 feet) is required, so that the liquid can be delivered to the pump without boiling. Since Viking pumps are of the positive displacement type, be sure that there is no obstruction in the discharge line and that all valves are in operating position before starting the pump.
All Viking 4924A Refrigeration Ammonia pumps are tested prior to shipment, but it is good practice to pressure test the pump, along with the rest of the system, before adding any ammonia. Other considerations include submergence, suction line, insulation, pump speed, system cleanliness and standby equipment. This is where Viking’s knowledge and expertise can assist with setup and operation of your ammonia refrigeration pump.
And of course, ammonia users should always take these basic precautions to avoid personal injury or damage to equipment:
- Look at pressure gauges to determine safe/unsafe conditions in the system
- Work carefully, don’t hurry
- Have plenty of water available
Potential health hazards
As with all chemicals, there are some potential health hazards to be aware of regarding ammonia handling. Exposure to ammonia causes intense irritation to the surface tissue of the eyes, nose, throat and lungs. Prolonged exposure to high concentrations of ammonia may blind, burn or even kill a person. The effect of ammonia on the skin is that of a caustic burn, varying in severity with the concentration of ammonia and the length of time exposed. Changes in respiratory and heart action are produced as reflex actions resulting from irritation of the respiratory tract. This makes it especially important to have proper safety practices and equipment in place when working with ammonia pumps, and only personnel familiar with ammonia systems should be allowed to work on or around these pumps.
This blog scratches the surface of information on ammonia refrigeration. The following resources contain more details on safety practices and equipment:
- ANSI - American National Standards Institute, Inc.
- CGA - The Compressed Gas Association, Inc.
Pamphlet G-2 on Anhydrous Ammonia
- IIAR - International Institute of Ammonia Refrigeration
- OSHA - Occupational Safety and Health Administration, U.S. Department of Labor