The U.S. domestic compressed gas industry is guided by the rules and regulations set forth by the Compressed Gas Association (CGA). They mandate what valve goes on what tank, what pressures cylinders can be filled to, cylinder labeling requirements and a myriad of other regulations too lengthy for this article.
The valves that are found on gas cylinders are, for the most part, pretty straightforward, however, there always exceptions to the rules. If we look at a helium cylinder for instance, we will find that through most of the spectrum of the helium grades the valve remains the same, a CGA-580 valve. However, if we increase the pressure rating of the tank we will find a CGA-680 or a CGA-677 valve. Electronic Grade Gases will commonly adopt a DISS (Diameter Indexed Safety System) valve. Electronic Grade Helium utilizes a DISS-718 valve.
There is commonly considerable confusion by customers when ordering gases by various grades as the valves will change in some gases as the grade changes. An Industrial Grade Air cylinder will carry a CGA-346 valve but when the grade is increased to a Dry or Zero Grade Air the valve changes to a CGA-590. Higher pressure Air cylinders require a CGA-347 or CGA-702 valve.
With the vast number of gases, gas grades, gas pressures, etc. available to customers there is no wonder there is often confusion. What to do? When ordering a particular grade of gas be sure to give the gas company all of the information necessary like, the grade of the gas, the cylinder size, the pressure requirement and the CGA valve number if known. The party receiving the information will reference a Specialty Gas Catalog for the appropriate valve configuration confirmation.
It is recommended that each customer have a Specialty Gas Catalog on hand as a reference for gas ordering.
If you are in need of a Specialty Gas Catalog or have questions concerning a gas, a CGA valve or regulation equipment please call me directly at 617-733-5946. We are here to help.