Fluid Coil Spec’s

Fluid Coil Specification

If your company’s HVAC system is not running at maximum efficiency, call Rahn Industries.  One of the things we can do is provide you with fluid coil specks that will let your system run better and run longer.  For example:


Coils shall be designed to withstand up to 650 psi maximum operating pressures and a maximum temperature of 500 degrees F for standard duty copper tube coils with standard headers.  Higher limits are available, depending on coil construction and/or materials used.


Coils are to be pressurized and then completely submerged in warm water for leak testing and tested with a minimum of 500 psi (unless higher pressure is required) air pressure for standard copper tube coils.  After testing, coils are to receive a 5 lb Nitrogen charge assuring the coil as received remains leak free and clear of internal contamination.

1.3 FINS

Coils shall be of plate fin type construction providing uniform support for all coil tubes.  Coils are to be manufactured with die-formed aluminum or copper with self-spacing collars.

Standard fin thicknesses available will include .006, .0075, .010 +/- 5% for aluminum and copper other thicknesses available

Fins are to be formed with full collar on all available materials, corrugation styles, tube diameters and tube patterns.

1.4   TUBING

Tubing and return bends shall be fabricated from UNS 12200 seamless copper conforming to ASTM B75 for standard pressure and temperature applications.

Core tubes shall be mechanically expanded to form an interference fit within the fin collars.  Expansion shall not decrease the tube wall thickness.

Coils shall be manufactured using return bends of the same material as the core tubing.  Return bend wall thickness, at the outside circumference of the bend, shall be no less than the core tube wall thickness.

Please call us for available tube size and wall thicknesses shall be as follows:

Coils shall be made available with copper tubes utilizing internally enhanced Rifled Surfacing when required.


Headers shall be constructed from UNS 12200 seamless copper conforming to ASTM B75 and B251 with an H55 temper for standard applications.


Standard construction of copper tube condenser coils shall allow for copper sweat connections for type L or K wall copper.  Other materials shall be made available dependent upon the materials of construction of the tube core.


Gas brazing, using fillet rod material of minimum 5% silver shall be used for all not-ferrous tube joints to headers and connections.  Ferrous to non-ferrous joints shall contain as much as 35% silver or may be Tobin bronze.


Coil casing and endplate shall be fabricated from 16 gauge Galvanized steel, as a standard construction, meeting ASTM and UL G90U requirements.  Aluminum, 0.080” thick, 16 or 18 gauge stainless are optional.  Double-flange casing shall be provided when coils are specified as vertical stacking.

Standard coil intermediate tube sheets (center tube supports) shall be fabricated from the same gauge sheet stock and material as the end plates and to the following schedule:

For custom-made field replacement condenser coils, all intermediate tube sheets shall be of the same quantity and placement as the original OEM coil.