Valve types check

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... 

Spring is broken in the spring-type check valve. 

Qieck Valve - A check valve is acceptable in a process pressure reheving path, provided that (1) the valve opens in the pressure reheving direction, (2) the valve is of the swing-check or wafer type with no external actuation or dampen mechanism, and (3) the pressure drop is included in the system analysis. 

Assumed the following valve types are NOT used as Isolation valves Air Operated Dlaphram, Solenoid Operated, Pressure Relief Safety, Swing Check, or Tilting Disk Check. 

Check Valve A valve which permits flow of fluid in only one direction. Often a check valve can be nothing more than a spring, ball, and seat separating two openings. Common valve types include in-line check valves and right-angle check valves. 

A valve is a mechanical device that controls the flow of liquids, gases, or loose material through piping systems. There are many types of valves, including butterfly valves, gate valves, plug valves, ball valves, and check valves. 

Nonreturn valves are used to prevent backflow of fluid in a process line. They do not normally give an absolute shut-off of the reverse flow. A typical design is shown in Figure 5.9g. Since swing-type check valves depend on gravity to close the valve, care must be taken to orient the valve properly when locating and installing it. 

Check valves. A check valve permits flow in one direction only. It is opened by the pressure of the fluid in the desired direction when the flow stops or tends to reverse, the valve automatically closes by gravity or by a spring pressing against the disk. Common types of check valves are shown in Fig. 8.4. The movable disk is shown in solid black. 

Water is flowing at a rate of 500 gal/min in a horizontal 10-in pipe. The pipe is 50 ft long and contains two standard 90° elbows and a swing-type check valve. What is the pressure drop ... 

Venturi-type valve trays Check incipient flood factor... 

There are many types of nozzles—ranging from the simplest, smoothly tapered nozzles to valved types which include automatic, hydraulically actuated shutoff and check valves. They are as individualistic in design as the molds which are used in injection molding. Figs. 4-6 and 4-7 illustrate some typical nozzles. 

This chapter discussed some specific valve types such pinch, rubber sleeve, and check valves. These valves have their own experimental loss coefficients, which need to be obtained from manufacturers. This chapter presented the conventional iCand the new two-A loss factors. The two-AT factor as developed by Hooper is of particular importance for slurry flows at low Reynolds numbers. The engineer should therefore avoid the common pitfall of using published data on turbulent water flows for conventional waterworks valves when estimating the losses in a slurry system. 

The BN-600 primary pump pressure nozzles incorporate flap-type check valves preventing backflow of sodium if one pump is deenergized. The check valve drive is hydraulic, responding to signals from the automatic control system. 

There is a capability to isolate each primary loop from the reactor using two gate valves on the suction and pressure pipelines of the circuit. On the pressure pipeline of each loop downstream of the PSP a flap-type check valve is provided eliminating coolant backflow in the event of a PSP trip in one loop when the other PSPs are operative. The secondary sodium circuits comprise EHX heat transfer tubes, pipelines, secondary sodium pumps and steam generators. Due to utilization of the reactor energy for fresh water production the steam-water system has some specific features. Steam from the SG is supplied to turbines of two types a condensing turbine (K-100-45) and a back-pressure turbine (K-50-45). Exhaust steam flows from the back-pressure turbine and from intermediate bleeds of K-100-45 turbine are supplied to the water desalination facilities. At a heat output of 750 MW the reactor produces ... 

Checks — before pressure testing, a functional inspection of each system is can ied out to ensure that it has been installed coireclly — for example, correct valve types, control valves the right way round, correct instruments fitted and so on. All vulnerable equipment such as pumps and control valves are fitted with temporary strainers. The system is then blanked off at each end, filled with water and pumped up to test pressure. The line/vessel test pressures must be compatible. Relief valve set pressures are tested on-site and tagged before installation. If necessary, relief valves are blanked during pressure testing of lines. 

Isolation valves being considered include gate valves, butterfly and ball valves. These valve types minimize system pressure drops when in the fully open position. The selected valve would need to be completely sealed from the space environment to prevent system leakage, with an external actuator to position the valve. A redundant actuator could be used to improve valve reliability and both actuators could be operated in parallel to free a sticking valve. The NRPCT does not have experience with solenoid operators on either the size valves proposed for the SNPP or at the temperatures proposed. Both valve performance, with respect to pressure drop (check valves), and valve actuation remain development challenges. 

Reciprocating pumps are those most commonly used in high performance Ic. The single-piston type usually has inlet and outlet check valves with some mechanism such as variable stroke frequency to minimize the effect of pump pulsations. Dual-piston pumps operate with the pistons 180° out of phase to minimize pulsations. For this system to work optimally, the piston units must be identical. 

The pumps can be either centrifugal or positive displacement types. The centrifugal pumps should have a head curve continuously rising toward the shut-off point. The standby pump should be piped into the system in a manner that permits checking of the pump while the main pump is in operation. To achieve this, a restriction orifice is required with a test bleeder valve piped to the return oil line or the reservoir. 

If a check valve is used in a system without an arrestor, excessive pressure may be exerted on the system when the reversing water column is violently stopped by the check valve. If a float-type air vent is located between the check valve and the closing valve, the float could easily be ruptured. 

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