Trade.Information

Product Name: Silent Check Valves

Product Description

The Silent Check Valve is the valve of choice in applications when silent operation and cost are of major concern. Its short linear stroke and spring return action combine to close the valve prior to flow reversal. This effectively eliminates the shock and water hammer normally associated with the sudden stoppage of a reverse flow. Its silent operation and low purchase price have made it a favorite of engineers in clear liquid applications. Specifications: - Scope 1.1 This specification is intended to cover the design, manufacture, and testing of 2 in. (50 mm) through 48 in. (1200 mm) Silent Check Valves suitable for pressures up to 740 psig (5100 kPa) water service. 1.2 The Check Valve shall be of the silent operating type that begins to close as the forward flow diminishes and is fully closed at zero velocity preventing flow reversal and resultant water hammer or shock. Connections 2.1 Globe style valves shall be provided in sizes 2 in (50 mm) through 48 in. (1200 mm) and have flanges in accordance with ANSI B16.1 for Class 125 or Class 250 iron flanges and ANSI B16.5 for Class 150 or Class 300 steel flanges. Iron flanges shall be flat faced. Sizes 10 in (250 mm) and smaller shall be capable of mating directly to a wafer butterfly valve without disc interference. 2.2 Wafer style valves shall be provided in sizes 2 in (50 mm) through 10 in. (250 mm) for installation between ANSI B16.1 Class 125 or Class 250 iron flanges or ANSI B16.5 Class 150 or Class 300 steel flanges. Design 3.1 The valve design shall incorporate a center guided, spring loaded disc, guided at opposite ends and having a short linear stroke that generates a flow area equal to the pipe size. 3.2 The operation of the valve shall not be affected by the position of installation. The valve shall be capable of operating in the horizontal or vertical positions with the flow up or down. Heavy duty springs for vertical flow down installations shall be provided when specified on 14 in. and larger valves. 3.3 All component parts shall be field replaceable without the need of special tools. A replaceable guide bushing shall be provided and held in position by the spring. The spring shall be designed to withstand 100,000 cycles without failure and provide a cracking pressure of 0.5 psi and to fully open at a flow velocity of 4 ft/sec. (1.22 M/sec). 3.4 The valve disc shall be concave to the flow direction providing for disc stabilization, maximum strength, and a minimum flow velocity to open the valve. 3.5 The valve disc and seat shall have a seating surface finish of 32 micro-inch or better to ensure positive seating at all pressures. The leakage rate shall not exceed one-half of the allowable rate for metal seated valves allowed by AWWA Standard C508 or 0.5 oz (15 ml) per hour per inch (mm) of valve diameter. 3.6 The valve flow way shall be contoured and unrestricted to provide full flow areas at all locations within the valve. Cv flow coefficients shall be equal to or greater than specified below and verified by an independent testing laboratory.