Coil Specifications

Design Pressures and Temperatures

Coil shall be designed to withstand the following maximum operating pressures and temperatures:

  • Water Coils 250 psig/300ºF
  • Steam Coils 125 psig/353ºF
  • Evaporator Coils (3/8" Coils) 400 psig/300ºF
  • Evaporator Coils (1/2" & 5/8" Coils) 250 psig/300ºF
  • Condensing Coils (3/8" Coils) 600 psig/300ºF
  • Condensing Coils (1/2" & 5/8" Coils) 300 psig/300ºF


Coils shall be plate fin type construction providing uniform support for all coil tubes. Coils are to be manufactured with die-formed aluminum or copper fins with self spacing collars which completely cover the entire tube surface.

  • Thickness 0.0060" +/- 5%*
    *unless specified otherwise
  • Tube Holes:
    • 0.375 diameter coils 10 through 20 fins/inch
    • 0.375 diameter spaced 1.0 inch equilaterally
    • 0.500 diameter coils 6 through 16 fins/inch
    • 0.500 diameter spaced 1.25 inch equilaterally
    • 0.625 diameter spaced 1.5 inch equilaterally
    • 0.625 diameter coils 6 through 14 fins/inch
  • All fins have a tolerance of +/- 4%

Testing Requirements

  • Coils shall be submerged in water and tested with dry nitrogen.
  • Water Coils are tested to 450 psig
  • Evaporator, Condensing and Steam coils are tested to 600 psig


  • Tubing and return bends - Standard pressure - constructed from UNS12200 seamless copper conforming to ASTM B75 and ASTM B251.
  • Copper Tube Temper - Light annealed with a maximum grain size of 0.040 mm and a maximum hardness of Rockwell 65 on the 15T scale.
  • Tube Expansion - Mechanically expanded to form an interference fit with the fin collars without decreasing tube wall thickness.
  • Minimum Thickness:
    • 0.016 inch for 0.500 and 0.375 inch tubing
    • 0.020 inch for 0.625 inch tubing unless specified otherwis


Headers shall be constructed from UNS 12200 seamless copper conforming to ASTM B75, ASTM B88 and ASTM B251.


High temperature filler metals shall be used for all brazed joints. Filler metal will contain at least 5% silver.


Acceptable coils are to have ARI Standard 410 certification and bear the ARI symbol. Non-certified coils or coils outside ARI's rating range will be considered if the manufacturer is a current member of the ARI air-cooling and air-heating coils certification program and the coils have been rated in accordance with ARI Standard 410.

Acceptable coils are to be Intertek Recognized Components, and are eligible to bear the ETL Listed Mark.