Valve Inlet Connections

This section summarizes the uniform American and Canadian standards for cylinder valve inlet connections in which a threaded joint is used to attach cylinder valves to cylinders and containers. A more complete discussion may be found in CGA V-1. [1] 

Oversize NGT threads are also available four and seven threads oversize are the most common. However, NGT threads can be provided for other oversize connections. The availability of oversize threads on valves prolongs the life of cylinders by compensating for the wear that occurs to cylinder threads from repeated valving operations. Oversize threads are also used by certain gas producers to differentiate their cylinders from others. Table 8-2 (Table 3 from CGA V-1) lists dimensions for features listed in Fig. 8-7 for the various tapered inlet thread sizes. 

Uniquely, chlorine valves have their own oversize thread series 0 threads oversize, 4 threads oversize, threads oversize, 14 threads oversize, and 28 threads oversize. Respectively, these are known as -14NGT (Cl)-l, I-14NGT (Cl)-2, -14 (Cl)-3, -14NGT (Cl)-4, and -14NGT (Cl)-5 threads. The (Cl) designation signifies chlorine. 

The Cl-5 type has been added recently. It is applicable to chlorine fuse plugs and cylinder valves. It is not used in chlorine ton container valves because it would interfere with the eductor tube attachment. 

In the chlorine application, oversize thread specifications apply only to the external valve thread. There are no oversize internal chlorine thread specifications for cylinders because the oversize valves are only used in conjunction with worn, out of specification, oversize cylinder threads. 

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Fig. 9-7. Typical straight thread valve inlet connection. Oversize threads...

For further information on cylinder valve inlet connections and other thread types presently in use, that is, special gas taper (SGT) threads and national gas straight (NGS) threads, refer to... 

An important application of a rupture disc device is at the inlet of a pressure relief valve. The sizing of the pressure relief valve or rupture disc device combination requires that the pressure relief valve first be sized to meet the required relieving capacity. The normal size of the rupture disc device installed at the inlet of the pressure relief valve must be equal to or greater than the nominal size of the inlet connection of the valve to permit sufficient flow capacity and valve performance. The failure modes of rupture discs are [40] ... 

Typical installation avoiding process laterals connected to pressure relief valve inlet piping... 

There are outlet ports in the manifold to provide connections to each subsystem. A similar manifold may be used in the return system. Lines from the control valves of the subsystem connect to the inlet ports of the manifold, where the fluid combines into one outlet line to the reservoir. Some manifolds are equipped with check valves, relief valves, filters and so on, required for the system. In some cases, the control valves are mounted on the manifold in such a manner that ports of the valves are connected directly to the manifold. 

A A. Process Lines Should Not be Connected to Safety Valve Inlet Piping. 

Blanco and Samadani37 obtained a patent for the construction of a microprosessor-based insulin pump that works in a similar fashion to the Biostator. The implantable infusion device consists of a catheter, an information-transmitting sensor located in the catheter, a microprocessor, a pump, the drug reservoir, and a power source. The pump, the sensor, and the valves are connected by appropriate leads to the microprocessor. The device is implanted in the subcutaneous tissue in the chest area, and the infusion catheter is tethered intravenously to a central location, such as the right atrium. The device is inserted with the inlet port facing outward so that it may be refilled periodically by a physician. 

Schmidt, J., Friedel, L., Westphal, F., Wtirsig, G., Wilday, J., Gruden, M. and Geld, C.v.d. (2001) Sizing of safety valves and connected inlet and outlet lines for gas/liquid two-phase flow, in 10th Int. Symposium on Loss Prevention and Safety Promotion in the Process Industries, EFCE, Stockholm. 

In addition, the length between the vessel to protect and the valve is too long and is connected with a pipe smaller than the SRV inlet connection, adding significandy to the pressure drop. It is clear that the pressure drop on this valve will be far above the 3% recommended by API. It would be wise to verify valve size as a first step, because the valve for this application could be undersized. 

CGA Pamphlet V-l-87, American Canadian and Compressed Gas Association Standard for Compressed Gas Cylinder Valve Outlet and Inlet Connections, ANSI, B57.1 CSA B96, 1987. 

Already performance car use inlet pipe of variable accoustic lengths. A well localised butterfly can be automatically actuated, offering two and sometimes tliree different design lengths. The origin of the variation of the maximum mass of air trapped inside a cylinder, a quantity directly coimected to the torque, is easy to understand. Imagine a pipe closed at 1 by a valve and connected to the atmosphere at 0 (fig.l). If you create a brief suction at I you will observe your... 

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