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G. Hydraulic Check Valve: <br /> ' 1. The hydraulic check valve shall be constructed with heavy cast iron <br /> or cast steel body with a bronze or stainless steel trim and a <br /> non-corrosive stem. <br /> ' 2. It shall absolutely prevent the return of water back through the valve <br /> when the inlet pressure decreases below the delivery pressure. The <br /> ' valve must be tight seating, and must be shockless in operation. <br /> The seat ring must be renewable and shall be securely held in place. <br /> ' 3. All material and workmanship shall be first class throughout. <br /> 4. The valve shall be a GA Industries, Inc., Fig. No. 2730-D or <br /> ' approved equal. <br /> H. Altitude Control Valve: <br /> 1. The altitude control valve shall be hydraulically operated, pilot <br /> actuated diaphragm type globe or angle valve designed for ground <br /> ' level control of water in an elevated storage tank and reservoirs. <br /> The valve operates on a differential in pressure between the height <br /> of the water in the reservoir and an adjustable spring loaded pilot <br /> ' control. The valve is to be non-throttling and will remain in the full <br /> open position until the shut-off point is reached. <br /> ' 2. The valve shall be constructed with a cast iron body (ASTM A126) <br /> with stainless steel stem or shaft and spring, bronze seat (ring) and <br /> upper stem bushing, nylon reinforced diaphragms, bronze valve <br /> control pilots with stainless steel and Buna-N internal parts. It shall <br /> be designed for an internal working pressure of 175 psi and. <br /> ' maximum differential pressure across the diaphragm of basic valve <br /> and pilots is not to exceed 300 psi. <br /> ' 3. The installation shall be designed for either one-way flow or two-way <br /> flow as indicated on the Contract drawings. <br /> a. One-way flow: The valve will be used where pressure on the <br /> inlet side of the valve is greater than the pressure created by <br /> the maximum reservoir or tank head. The valve's sole <br /> ' function is to fill an elevated tank or reservoir to a desired <br /> level. <br /> b. Two-way flow: The valve will be used when pressure on the <br /> inlet side is variable. When inlet pressure falls below <br /> reservoir pressure the valve opens, allowing reverse falls <br /> ' Rev. 10/22/01 PROJECT#13.01126 02640-Page 7 <br />