Armstrong Duralite™ Plate Fin Coils meet the diverse needs of the HVAC and light industrial markets. Building on a tradition of quality and dependability, these heavy-duty industrial coils have been serving the process needs of heavy industry for nearly half a century. The coils are available in Centifeed (Steam Distributing Tube Type), Standard (Opposite End Connections), and Two-Row Return Bend Construction.

Construction and Materials

Casings

14 or 16 Ga galvanized steel, depending on size and material. Options include aluminum or stainless steel.

Fins

• Types: V-waffle, HTE or flat: 6 to 14 FPI
• Aluminum: .008", .010", .012" thick
• Copper: .006", .009" thick

Tubes

• 5/8" OD x .028" thick copper (Options: .020" or .035" or .049" copper)
• 1" OD x .032" thick copper on One-Row steam coils (Option: .049" thick copper)
• 5/8" OD x 0.049" copper nickel

Connections

• Headers: Minimum .060" to .134" thick copper or copper nickel, depending on coil size.
• Vent connections: Top and bottom on all liquid coils, top of condensate header on Standard steam coils.

Connection Types:

• H = Liquid Heating Coil
• S = Standard Steam Coil
• C = Centifeed Steam Coil
• R = Return Bend Steam Coil
• V = Vertical Tubes/Horizontal Air

How to Identify the Circuiting and Hand of a Return Bend Coil

Circuiting:

1. Identify the inlet header and count the number of tubes fed from it.
2. Count the number of tubes in the face of the coil.
3. Divide the number of tubes fed from the header by the number of tubes in the face. The result is the identification of the coil's circuit.

Hand:

1. Face the coil with the airflow at your back.
2. Point to the outlet connection (top of a liquid coil, closest to you; or condensate return connection on a steam coil, farthest from you).
3. The connection on your right indicates a right-hand coil; on your left indicates a left-hand coil.

Steam Coils

Armstrong Duralite™ Plate Fin Steam Coils are available in Centifeed, Standard, and Two-Row Return Bend Construction. Centifeed, Standard, and Return Bend coils are made of 5/8" OD tubes as a standard. One-Row coils are available optionally with 1" OD tubes.

WARNING

Depending upon steam flow, long Centifeed coils may require steam to be fed from both ends to eliminate cold tube ends and subsequent freezing potential.

Standard Steam Coils

Centifeed Steam Coils

Centifeed Steam Coils Fed From Both Ends

Return Bend Steam Coils

Liquid and Cooling Coils

Armstrong Duralite™ Plate Fin Heating Coils are available in Return Header design in one- or two-row configurations and Return Bend design in two or more rows. Liquid coils are made of 5/8" OD copper tube. Cooling coils can be built from 2 to 12 rows and with double, full or 1/2 circuits. Custom circuits are also available.

Return Bend Heating & Cooling Coils / Return Header Heating Coils

Installation and Operation

Liquid Coils

• Install the coils level to ensure complete drainage during shutdown.
• Supply liquid to the bottom connection and return from the top.
• Ensure that liquid and air flow through the coil in opposite directions unless instructed otherwise.
• Support coils and piping individually to prevent undue strains on the connections. Use swing joints or flexible connections.

WARNING

Do not use throttling controls in hot water heating service if there is a possibility of below freezing air passing through the coil. Use a face and by-pass system to control temperature.

Steam Coils

• Install a drip trap prior to the coils (and before a control valve if there is one) to prevent the introduction of condensate.
• Install a vacuum breaker in the steam piping prior to the coil to prevent retention of condensate during shutdown. Also install a vacuum breaker on the downstream side of the coils when steam pressure is to be modulated.
• Vent non-condensable gases individually on each coil to ensure maximum heat transfer and minimum internal corrosion.
• Trap all coils individually. Use only traps such as the inverted bucket or float and thermostatic which drain continuously.
• To provide maximum freeze protection, maintain a minimum steam pressure of 5 psig to coils exposed to air temperature below 40°F (5°C).

Piping practices for steam heating coils

Steam Trap Selection Guide

Equipment	Selections	Constant Pressure (0 - 30 psig)	Constant Pressure (Above 30 psig)	Modulated Pressure (0 - 30 psig)	Modulated Pressure (Above 30 psig)
Unit Heaters	1st Choice 2nd Choice	IBLV F&T	IBLV F&T	F&T IBLV	F&T IBLV
Air Handlers	1st Choice 2nd Choice	IBLV F&T	IBLV F&T	F&T IBLV	F&T IBLV
Process Coils	1st Choice 2nd Choice	IBLV (0-250 psig) F&T (0-250 psig)	IBLV (Above 250) IBLV (Above 250)	F&T IBLV	F&T IBLV