Cylinder valve diaphragm

Fig. 1.4 A cross section of a diaphragm compressor. (1) plunger piston, (2) oil cylinder, (3) diaphragm (4) and (5) in and out feedthroughs, respectively, for compressed gas. (The check valves are not shown.) (From reference 2 with modifications.)...

CFR1910.253(b)(5)(ii)(R) (3) 4.5.6.2 Complete removal of the stem from a diaphragm-type cylinder valve shall be avoided. [NOTE Stems may be removed before cylinder disposal]... 

As noted above, compressor bodies usually are carbon steel. Diaphragms are stainless steel or Monel, and cylinder valves are Monel. Preventive maintenance should include periodic replacement of diaphragms and sealing the apparatus with clean, dry air or nitrogen during its fiequent idle periods. 

Because of the tendency for buildup of particulates, cylinder valves on technical grade hydrogen chloride cylinders are normally wrench operated to facilitate application of torques in excess of that which can be applied manually with a handwheel. Electronic grade hydrogen chloride cylinders are equipped with a tied-diaphragm valve. 

Cylinders require the installation of a valve that will permit the withdrawal of the mixture. The valve used on a cylinder for a given mixture must be selected so the materials of construction are compatible with ail mixture components. The type of valve, packed or diaphragm, is chosen based on the integrity and regulatory requirements of the mixture. The outlet connection is selected based on the physical and chemical characteristics of the components. CGA V-7, Standard Method of Determining Cylinder Valve Outlet Connections for Industrial Gas Mixtures, is a guide for the selection of outlet connections for mixtures. It includes numerous examples of how to apply the selection procedures [12]. 

The most common cylinder valve used for dichlorosilane is a stainless steel diaphragm valve with a Connection CGA 678 outlet. The cylinder valve body has a combination CG-4 type pressure relief device consisting of a fusible metal plug, melting about 165°F (74°C), which is protected from the cylinder contents by a frangible metal disk, i.e. a rupture disk, rated at 250 psig (1724 kPa). 

Cylinder valves are generally of two basic types, the packless (diaphragm) type and the packed t3q)e. These two types are described in detail below. 

Packed valves similarto the cylinder valve previously described, may also be used. They have an advantage over diaphragm valves when regulating flow since regulating stem tips (seats) may be used with very fine threads on the stem to allow for precise flow control. The packed design... 

Fig. 4.1-35. Diaphragm compressor (HOFER). a, Diaphragm b, Gas space c, Discharge valve d, Suction valve e, Diaphragm cover f, Perforated plate g, Hydraulic cylinder h, Oil overflow valve i, Oil return j, Cylinder cooling k, Check valve 1, Crank drive m, Cooling-water in/out n, Oil-cooling coil o, Oil chamber p, Oil injection (leakage compensation) q, Compensation pump r, Check valve s, Oil supply.

Volumetric flow is regulated by throttling a diaphragm-type control valve in this nonlubri-cated, vertical, three-stage, two-cylinder hydrogen compressor. (Courtesy of Koehler and Hoerter GmbH.)... 

Warning Never connect a gas cylinder directly to a closed system that is not specially designed to withstand high pressures (such as a combustion bomb for heats of combustion). Even when a regulator is used, remember that the diaphragm valve may slowly leak arrange for some kind of safety pressure release, if only a rubber tubing connection that can be easily blown off. 

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