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Direct Expansion Coils


Direct Expansion Coils – Type DX

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Primary Surface

Round seamless copper tubes are mechanically expanded into the fin collars of the secondary surface. The mechanical expansion provides a permanent metal-to-metal bond for efficient heat transfer. Tubes are staggered in the direction of airflow and only RETURN BENDS are used – NO reduced tube wall in the bend radius by hairpin bends.

Tube Size Options:

 5/8” o.d. options ( tube wall thickness / return bend thickness ) ( .020” / .028” ) ( .025” / .035” ). Tubes are centered on 1.50” in the tube face and 1.299” between rows.

½” o.d. ( tube wall thickness / return bend thickness ) ( .017” / .025” ). Tubes are centered on 1.25” in the tube face and 1.083” between rows.

Rows available are 1,2,3,4,5,6,8,10 and 12.

Secondary Surface

Corrugated plate type fin that is die-formed. Fin collars are full-drawn to provide accurate control of fin spacing and maximum contact with tubes.

Fin Material Options:

5/8” tubes come standard with aluminum fin .008” thick with optional (.010). Optional copper fin thicknesses are (.006) (.008) (.010). Fins per inch available are 6 through 14.

½” tubes come standard with aluminum fin .006” thick with optional copper fin thickness of (.006). Fins per inch available are 8 through 14.


Seamless copper with die-formed holes that provide a parallel surface to the coil tube for strong brazing joints.


Copper O.D. sweat with interchangeable nozzle type refrigerant distributors. Standard coil has one distributor for one compressor circuit. An INTERTWINED coil has two distributors that provide full face control using two compressor circuits. A FACE SPLIT coil has two or more distributors for multiple compressor circuits.


Using 16 ga. minimum thickness material, 1 ½” flanges are die-formed to permit easy stacking and mounting. Intermediate tube supports are supplied on coils over 44” fin length with an additional support every 42”.

Casing Material Options:

Full G-90 galvanized steel standard with optional 304 & 316 stainless steel.

Testing & Performance

All coil assemblies are leak tested under water at 315 PSIG nitrogen. Standard construction is suitable for 250 PSIG and up to 300 degrees F.

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