Valves lift check valve

Figure 15-11. Lift check valve. [Courtesy of Jenkins Bros.)...

An oil with a 32.6° API gravity at 60°F is to be transferred from a storage tank to a process unit that is 10 ft above the tank, at a rate of 200 gpm. The piping system contains 200 ft of 3 in. sch 40 pipe, 25 90° screwed elbows, six stub-in tees used as elbows, two lift check valves, and four standard globe valves. From the pump performance curves in Appendix H, select the best pump to do this job. Specify the pump size, motor speed, impeller diameter, operating head and efficiency and the horsepower of the motor required to drive the pump. 

Lift Check Valves These valves (Figs. 10-160 through 10-162) are made in three styles. Vertical lift check valves are for installation in vertical lines with flow normally upward. Globe (or piston) valves with a 90° bonnet (Fig. 10-161) are for installation in horizontal lines, although inclined bonnet versions (approximately 45°) with spring... 

Lift Check Valve. A lift check valve is similar in design to a globe valve except that the disk is Ufted by the forward line pressure and closed by gravity and backflow (Fig. 5.185). 

Check Valves Tlie pmpose of a check valve is to allow relatively unimpeded flow in the desired direction but to prevent flow in the reverse direction. Two common designs are swing-tvpe and lift-type check valves—the names of which denote the motion of the closure member. In the fonvard direction, flow forces overcome the weight of... 

Nominal valve size Gate Globe, lift check, swing check A and B Angle and lift check B... 

For the standby pump start test, which is an important test to ensure the pumps transfer without large pressure swings, a check should be made to see if the relief valves lift or the pressure falls to a pressure one half the difference between the standby pump start pressure and the compressor trip pressure. The transient pressure is best measured with a multipen chart recorder. The chart speed must be high enough to fully display the pressure variation. While not as good as the chart recorder, a simple shop-made test setup can be substituted. A spare switch is temporarily connected to the same location as the other switches. This switch is calibrated to close at the threshold acceptance pressure. The contacts are wired to a test light through a seal relay. The purpose of the relay is to maintain the cir-... 

A continuous flow reactor vessel contains a liquid reacting mixture with a density of 0.85 g/cm3 and a viscosity of 7 cP at 1 atm pressure. Near the bottom of the vessel is a I i n. outlet line containing a safety relief valve. There is 4 ft of pipe with two 90° elbows between the tank and the valve. The relief valve is a spring-loaded lift check valve, which opens when the pressure on the upstream... 

Bailers are pipes with an open top and a check valve at the bottom, which are used to retrieve liquid samples from groundwater monitoring wells, tanks, pits, and drums. When a bailer is lowered on a cord into the water, the bottom check valve opens allowing the bailer to fill with water and to sink. As the filled bailer is lifted from the water, the check valve closes to retain the water. A sample is obtained from the bottom end of the bailer by opening the check valve with a bottom-emptying device. 

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