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Globe Valves
Swing Check (One-Way) Valves

Aviation Boatswains Mate F - Aviation theories and other practices
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that other types of valves also may have globe shaped bodies. Therefore, the name does not always describe the valve properly. In a globe valve, the disk is attached to the valve stem and seats against a seating ring or seating surface that shuts off the flow of fluid. When the disk is moved off its seat, fluid can pass through the valve. Globe valves may be used to limit fuel flow through the valve (called throttling) by partially opening the valve to meet the desired flow. Globe valves are most commonly found on pump discharges, tank mani- folds, JP-5 purifier discharges, and any other place where there is a need for throttling fuel flow. Globe valve inlet and outlet openings are ar- ranged in several ways and are used to suit the re- quirements of the flow. There are three common types of globe valve bodies. In the straight body, the inlet and outlet openings are in line with each other. In the angle body, the inlet and outlet openings are at an angle to each other. The cross globe valve has three openings instead of two, and is frequently used in connection with bypass piping. High Performance Butterfly Valves The high performance butterfly valve (fig. 4-16) used in the JP-5 system is designed specifically for flammable liquids or other hazardous materials. If a fire guts a piping system or space where these valves are located, and the fire is hot enough to melt a special sealing element, a secondary metal sealing takes place providing effective shut-off of fluid flow through the piping. No feeding of the fire can take place. The high performance butterfly valve has a sin- gle-piece flexible polymeric seat that is pressure ener- gized to assure positive shutoff. The seat is so designed that is compensates for pressure and tem- perature changes as well as for wear. The design also allows no metal to metal contact during regular operations.  Also  contributing  to  the  valve’s effectiveness is its offset shaft and eccentric disk design that impart a camming action to the disk. This feature causes the disk to swing completely out of contact with the seat upon opening, eliminating wear points at the top and bottom of the seat. This arrangement allows replacement of the valve seat, if it is ever required, by simply removing the body insert and then replacing the seat. You do not have to disassemble the shaft or disk. With no Figure 4-16.—High performance butterfly valve. requirement to remove the shaft and disk, repair time is cut dramatically. As with the gate valve, the high performance butterfly valve allows fluid flow in either direction. High performance butterfly valves are normally used as isolation valves in distribution piping, but they may be used nearly anywhere. Limitorque Valve Operators On newer CVNs, numerous valves have limitor- que valve operators. Limitorque valve operators (fig. 4-17) open and close gate and globe valves from a remote location, usually the pump-room console (which will be discussed later in this chapter). Each limitorque, in addition to operating a valve, also controls and limits the opening and closing travel of the valve. A torque limit switch on the limitorque protects all operating valve parts from overload by 4-20







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