With Closed Coupled Valve
The rate of flow controller shall consist of a Venturi Tube and a close coupled butterfly valve properly sized
for the application. The ends of the controller shall be flanged ANSI 125#, and the flange to flange laying
length shall be as shown on the drawings. Both flanges shall be line size without the need for reducers,
increasers, or adapters. The controller shall be optimized for close piping conditions such as filter effluent
rate of flow applications. The throat shall be selected for a differential of approximately 60” W.C.
The Venturi shall utilize static pressure taps only. Devices employing Pitot effects, amplifying the differential
by causing changes in the direction of the flow at the inlet and/or throat cross sections, or introducing
unwanted noise are not acceptable. The inlet section shall incorporate a hydraulic shape employing at least
two distinct vena contractae to condition the flow pattern before it enters the throat section. Designs utilizing
elliptical approaches or transitions shall not be acceptable. The throat section shall have a length equal to
at least one half the throat diameter. The recovery section shall be truncated and have an included angle
of 10 degrees.
The controller body shall be constructed of cast iron, ASTM specification for Gray Iron Casings for Valves,
Flanges and Pipe Fittings, Designation A-126, Class B; or fabricated of carbon steel. The Throat liner shall
be Bronze or 316 SS, and the tap bushings shall be 316 SS. Internal ferrous surfaces shall be coated with
a NSF approved epoxy paint system. Exterior finish shall be red oxide universal primer.
The Butterfly type “Control Valve” shall be an AWWA tight closing, rubber seated butterfly valve bolted to
the flow element recovery cone. The valve disc shall be cast iron, and the shaft shall be stainless steel. The
supplier shall co-ordinate the Venturi outlet clearance and the valve disc swing to insure that there is no
interference. The valve shall be sized according to the optimum control range of the valve disc for the
specified flow rate. Controller head loss shall not exceed 18” W.C. with butterfly valve fully open.
The Flow controller shall be BIF model 20612, utilizing a Universal Venturi Tube and AWWA butterfly valve,
or Engineer approved equal.
The rate of flow control loop responsibility shall be provided by a single manufacturer, and the major
components comprising the loop such as: flow controller, flow transmitter, actuator, and electronic controller
shall be provided by a single manufacturer/supplier bearing the loop responsibility.
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