Self-closing valves

Laboratory supply houses feature sink-mounted faucets heavily plated with inert metals for DI water. Less expensive plastic valves, available from plumbing supply houses, may be used as long as they contain no metal parts. Self-closing valves, while more expensive, will substantially reduce DI water consumption. 

NFPA 30,5.5.2.1 4.4.21 If hose is used in the transfer operation, it shall be equipped with a self-closing valve without a hold-open latch in addition to the outlet valve. Only listed or approved hose shall be used. 

If self-closing valves have been provided, these should never be blocked or tied open. 

Self-closing valves are used where failure to close a valve manually might permit flow of oil or gas into areas where a serious fire may result. The types of installation for which self-closing valves should be considered include water and chemical draws, vents, bleeders, drains, level cocks, sample points, and tank truck and barrel filling and emptying systems. 

A fuel port is provided for filling the EFC with fresh fuel, along with an exit port for consumed fuel and waste products. For oxygen-sensitive EFCs, the ports must be reclosable or equipped with self-closing valves. 

Pressure relief valves, self-closing doors... 

For removing water floating on a chlorinated hydrocarbon bottom layer, two or three drain valves at easily accessible positions should be provided. The valves should be fitted close to the tank sides to avoid the danger of the drain lines freezing up. Product tanks should be fitted with pressure-vacuum valves and with self-closing dip and sample hatches. 

It is undesirable to have single valves opening to the atmosphere at the bottom of tanks unless such valves are normally blanked off. Therefore, sampling the bottom of a tank should be via a dip hatch in the tank top with a bottom sampler. A self-closing dip hatch is recommended. 

A down-hole safety valve (DSV) is located underground. This is a self-contained valve that operates on high flow and does not require external signals or power for its operation. The valve is normally open, and closes automatically when its differential pressure reaches a predetermined value. Based on the flowing capabilities of the well, each valve is adjusted to accommodate the fluid, pressure, temperature and flow rate of the well. 

Provide fire-safe or self-closing charging valves if required. 

Many vendors now sell gas cabinets equipped with self-closing and latching doors and windows, sprinkler heads and various types of purge assemblies (see Fig. 5). Cabinets should be provided with a minimum flow of 100 feet per minute through the louver on the cabinet bottom. When the window is opened, the face velocity through the window should be maintained at 100 fpm. Purge assembhes may contain many different types of safety devices. An emergency shutoff valve should be located as close to the cylinder as is practicable. An air operated remotely activated cylinder valve is more preferable. System shutoff may be by manual activation of a remote switch in the laboratory or fabrication area or caused by other system defaults interlocked to gas flow. System defaults may include ... 

Truck-filling valves should be of the spring-loaded, self-closing type. 

Cell closure Self-closing safety valve Plastics seal or self-closing or non-resealing safely vent... 

Explosion isolation can also be effected by rapid action barrier valves. At present, they can be arranged only in horizontal pipehnes and are suitable, in general, only for streams with a small amount of dust. Such valves are thus frequently used to protect ventilation lines. As a certain explosion overpressure is necessaiy to close such valves, a distinction is made between self-actuated and externally actuated barrier valves (Fig. 26-46). 

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