Stop check valve

STOP-CHECK VALVES (Globs and Anglo Typos)... 

Stop check, which combines design characteristics of both a lift check and a globe valve. In the closed position, the stop check disc is firmly seated. In the open position, the stem rises out of the body of the flow control element and acts like a guide for the disc. In the open position, the stop check valve functions like a lift check valve with one exception The degree of lift can be controlled. 

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. 

Check valves are required in the piping system at any point where backflow of gas after a shutdown has the ability to restart the compressor, running it backwards or, for that matter, even in the normal direction. Reverse rotation is totally bad, as many components of the various compressor types are not designed for reverse rotation, and there is some possibility, generally remote, that the compressor could reach a destructive over speed. Forward rotation is bad primarily because the intent was to stop the compressor, and it is now operating out of control. This is a problem, particularly if the shutdown was caused by a compressor failure indication, and the need to stop was to prevent further damage. In this mode, it is unlikely that the compressor can attain an overspeed condition. An application with a high potential for backflow is the parallel operation of two or more compressors. 

Remotely operated emergency isolation valves (see Section 7.2.1) should be fitted on filling lines. If the hose breaks for any reason, the flow can be stopped by pressing a button located at a safe distance. Reverse flow from the tank truck or car can be prevented by a check valve. 

Driven 2.2.1.2 Controllen-Rieumatic 3.5.1.1 Valves-Operated-Stop Check... 

Taxonomy No. 3.5.1.1 Equipment Description VALVES-OPERATED-STOP CHECK ... 

Sperr-klmke, /. catch, pawl, ratchet, detent, -kreis, m. block circuit, wave trap circuit, -metail, n. ply metal, -rad, n. ratchet wheel, cog wheel, -schichtenzelle, /. solid photovoltaic cell, -ung, /. shutting, etc. (see sperren). -ventil, n. stop valve, check valve, shut-off valve, -waffe, /. defensive weapon, -wasser, n. sealing water. 

NOTE A corporation stop is a chemical injection device that screws into a recirculating cooling waterline. It includes a nozzle assembly to disperse chemicals into the center of the line for even mixing (although sometimes a static mixer is a useful extra) and permits the removal of the injection check valve without the need to shut down the line. 

Figure 1. Schematic diagram of the experimental apparatus (PG, pressure gauge TC, temperature controller HT, heating tape MV, metering valve SV, stop valve CV, check valve RD, rupture disc P, HPLC pump)...

Gate voiw Globe valve Lubrotite volvC Check voive Stop check Plug voive... 

Special nozzle screens fitted with a check valve help prevent nozzle dripping. Check valves should be used in situations where a sprayer must be stopped and started frequently, such as in small target areas, near sensitive crops or areas, indoors, or for right-of-way treatments. The operator must check these springdoaded ball valves frequently to assuie proper operation. 

Gate valve - Globe valve Lubrotite volve — Check valve - 3— Stop check —oh— Plug valve —oh— Noftiubriceted plug volve —oh— Quick opening volve... 

The piston is directly attached to a device that is pushed inside a cylinder by means of a constant speed rotating motor. The pump delivers a constant flow (without any pulsation) and check valves are not needed. The performance of a syringe pump is dependent on flow rate, syringe size and the architecture involved [24], In the more sophisticated models, the motor speed and rotation can be varied, which offers real advantages for analytical applications involving multi-reagents, sample stopping or flow reversal. 

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. 

For sizes larger than 2 inches, the swing-check valve is most often used. Chattering caused by frequent flow reversals can be stopped by using this type of valve equipped with an outside lever and weight. Checks are used in process pump piping after the discharge nozzles to prevent liquid backup in case of pump failure. 

Lubrotite yofve Check valve Stop check Plug valve... 

On a number of occasions the pump stopped operating, the check valve failed to hold and light hydrocarbons flowed backward from the process into the tank. A layer of hydrocarbons formed on top of the inorganic liquid, as shown in Figure 1.21. No instrumentation was installed to warn of the occurrence of this event. 

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