Random Miscellaneous Stuff That It’s Useful to Know if You’re Working in Labs

Compressed Gas Cylinders All high pressure gas cylinders must be secured with a chain. Cylinders must not be moved unless the protective valve bonnet is in place. Cylinders not in use must also have the valve bonnet in place. Without the valve bonnet protecting the valve, an accident could knock off the valve stem, creating a lethal rocket that can easily penetrate a masonry wall. I once worked with a guy who forgot to chain up his chlorine cylinders on his delivery truck. Of the seven cylinders that fell off the truck, the valves only broke off of four.

Compressed Gas Cylinders Always use a pressure-reducing regulator when withdrawing high pressure gases. Before installing the regulator, clean the cylinder fitting to remove dirt, including bugs and spider webs Opening the cylinder valve for a fraction of a second before installing the regulator does a marvelous job of removing spider webs! Never allow any grease or other contaminant to come in contact with a gas regulator or cylinder. Specifically, grease and high pressure oxygen form an explosive mixture.

Compressed Gas Cylinders For specific requirements for specific chemicals/gases, see the Matheson Gas Databook. (Copy in JFB 329) For example, acetylene is incompatible with copper, silver and mercury. Acetylene also decomposes spontaneously at pressures greater than 15 psi and in open atmosphere. It must never be allowed to collect by itself outside the tank and lines...light it immediately on opening the torch valve. Acetylene is shipped dissolved in acetone. Acetylene cylinders are filled with a porous material (chalk!) which holds the acetone.

Compressed Gas Cylinders The seal between the regulator and cylinder is a ball and socket, not a tapered thread. Any attempt to put Teflon tape on the threads will cause you to get laughed at with good reason. The operation of regulators is counter-intuitive: screwing the knob in (clockwise) increases the output pressure. If you screw the knob out far enough, you can actually pull a vacuum on the regulator with the cylinder valve open! Only cylinders containing the same kinds of materials have compatible fittings. Hence a regulator with a fitting for an oxygen cylinder will not fit onto an inert gas cylinder. The fittings for fuel gases have left hand threads, signified by cuts on the nuts. Always move gas cylinders with a gas cart...after attaching the bonnet.