The International Institute of Ammonia Refrigeration (IIAR) has a new pipe marker guideline, #114, "Guidelines for: Identification of Ammonia Refrigeration Piping Components".

1. Ammonia Abbreviation
   BD Booster Discharge
   CD Condenser Drain
   DC Defrost Condensate
   ES Economizer Suction
   HGD Hot Gas Defrost
   HPL High Pressure Liquid
   HSD High Stage Discharge
   HSS High Stage Suction
   HTRL High Temperature Recirculated Liquid
   HYRS High Temperature Recirculated Suction
   LTRL Low Temperature Recirculated Liquid
   LTRS Low Temperature Recirculated Suction
   LIC Liquid Injection Cooling
   LSS Low Stage Suction
   RV Relief Vent
   TSR Thermosyphon Return
   TSS Thermosyphon Supply
    
2. Physical State
   LIQ Liquid (orange background)
   VAP Vapor (sky blue background)
    
3. Ammonia is Black Letters on Yellow Background
    
4. Pressure Level
   LOW Low Pressure (under 70psig; green background)
   HIGH High Pressure (70psig or greater; red background)
    
5. Flow Direction

The Ammonia standard was developed as a result of the phase out of CFC's and the desire to create a uniform, international piping standard for the food processing industry. The designs are quite complex, but once the system is understood, these designs outline a logical color-coded system.

It is interesting to note that this is one more international industry trying to shoehorn their needs into the restrictions of ANSI 13.1.

Finally, many ammonia pipes are very cold. In these situations, it is important to avoid vinyl Snap-on markers for the pipe markers, which, unlike polyester, tend to embrittle faster in cold temperatures.