AC Flow Control Valve

The Coen AC Flow Control Valve (Adjustable Characteristic) is the result of over forty years of continuous development and improvement.  The original design (U.S. Patent 2,315,171) provided a high lift, easily adjusted, fine regulation, cam type valve with an adjustable flow characteristic for control of gas or oil fuels.  The present AC Valve provides all of these features with the addition of reverse acting lever operation, low operating torque (approximately 30 inch pounds), flexibility of installation, compactness, a balanced piston type valve plug with characterized valve ports, and mechanical and material refinements for unequaled service.

For mechanically driven fuel control valves, the Coen AC Valve is unequaled. If your burner is equipped with a second rate fuel control valve that sticks or won't repeat, why not replace it now with the best? The Coen AC Valve provides repeatable smooth fuel control and wide turndown. It is simply the best.

• Dimensions & Capacities

Performance Characteristics

The Coen AC valve makes an ideal fuel flow control valve for use in combustion control systems.  Not only can maximum and minimum fuel flow be adjusted to exact desired amounts, but the valve characteristics (or flow with respect to valve position) can be adjusted as desired over the entire range.  In positioning type combustion control systems, the AC valve is linked directly to the combustion air damper.  At any given damper position the AC valve may be adjusted to provide exactly the desired amount of fuel flow.  Thus, the AC valve makes it possible to fire efficiently over a wide firing range by closely matching fuel flow to air flow.  Twenty one screws on the AC valve are used to ensure precise controllability of fuel flow over wide firing ranges.

The AC valve is also a key element in Constant Differential Control (CDC) metering type combustion control.  In this system, a constant differential valve upstream of the AC valve (with pressure taps across the AC valve) meters fuel flow on the principle that for a constant pressure differential, flow will be proportional to orifice (or valve opening) size.  This system, therefore, truly meters fuel flow and will maintain constant flow at any valve position even though external conditions vary.   

The AC valve is adjusted in the field by the analysis of the products of combustion to establish fuel flow. At any given valve position, fuel flow is controlled by one of twenty one adjusting screws.  When proper fuel-air ratios are determined, the adjusting screw is locked in position.  Once set up and locked, the AC valve will closely maintain original fuel flow.

Mechanical and Material Features

All Coen AC valves use the same "reverse acting" top works, consisting of bracket, cam plate, screws, lever, roller, shaft and spring assembly.  The 21 hardened adjustment screws are fitted with locknuts and lock washers.  Toggle connections are used between valve plug, valve stem and shaft.  The lever shaft is supported in needle bearings with dust seals.  A thrust bearing is used between spring assembly and shaft.  The lever roller is mounted on a needle bearing.  The valve rod is 5/16" monel.  The oil valves feature replaceable matched chrome alloy sleeves and hardened, ground plugs, with characterized ports. The gas valves are doubled ported with characterized ports.

Installation

Coen AC valves are furnished with self-aligning rod end bearings adapted to half couplings, with 9/16" length of adjustments allowing for field fitting of threaded pipe to make up drive and connection rods.

As with other precision control valves, constant supply pressure conditions are required at all times.  Good quality pressure regulators should be located upstream of the valve close enough to ensure a constant supply pressure.

AC valves must be protected form foreign material. The installation of wye strainers with 1/32" perf. screen for oil (1/64" per. for 1/2 port valves) is recommended.  Gas AC valves, especially on new gas lines, should be protected.

There are numerous ways that Coen AC valves may be incorporated into combustion control systems.  Consult your nearest Coen agent or write Coen Company for information and typical installation drawings.

The Coen AC Valve...for Flexibility and Smooth Fuel Control.  

For more information about this product, talk to your nearest Coen Sales Representative.

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