Often the gas in the cylinder is at the appropriate purity level for the application for which it is intended. Be cautious in your purchase of pressure regulators for the cylinder as it must be of the right type and have the appropriate components of construction so as not to contaminate the gas as it is passed through the regulator.
Far too many times I have conducted purity audits of laboratories and found a "General Purpose" regulator on a gas of Grade 5.0 or higher quality.
A Grade 5.0 Helium for instance is 99.999% pure. It will have <1ppm of moisture, <0.5ppm of Hydrocarbons and < 1 ppm Oxygen. That is a darn clean gas. It is the gas company's job to make it that way and it is also our job to recommend the right regulator to go along with the gas.
Many companies have turned to the catalog sales companies to purchase their regulators to save a few dollars. Here is where the "wrong" regulators come into play for the most part. High purity and Ultra High (UHP) purity gases require regulators with a polished brass body, stainless steel diaphragms, Teflon and or Tefzel seats and seals with a Helium leak integrity of 1 x 10 to the minus 9. Now that is a clean, high purity regulator.
Most times I see regulators on these gases with a forged brass body, a neoprene diaphragm and no listed leak integrity. This regulator will contaminate the gas the moment it passes through the body. It will draw atmosphere and contribute moisture and Oxygen. The diaphragm is neoprene, which is a Hydrocarbon. The very thing the gas company takes out of the gas to make it Ultra High Purity, the regulator puts back in.
Be sure the regulator fits the application. In most cases the regulator is inferior, but then there are the cases where the customer is overly cautious and buys all stainless steel regulators. An all stainless steel regulator is an excellent choice when working with a corrosive type gas, however it is a significant overbuy when working with, say an Ultra High Purity Helium.
The brass regulator will work perfectly with the UHP Helium as will the stainless steel, the difference is the stainless steel will be priced at approximately 100% higher than the brass model. The wrong "General Purpose" regulator will cost approximately 100% less than the brass high purity regulator.
When making a choice of regulators know the difference in "single stage" and "two stage" regulators. A two stage regulator has two diaphragms and will maintain a constant pressure throughout the life of the gas cylinder. A single stage regulator will adjust its own pressure up as the gas cylinder depletes itself of product. If your application calls for a steady pressure, a two stage regulator is your best choice.
It may all sound confusing but a gas supplier who is conscious of the differences in regulators will steer you straight. Whether you are a customer of Middlesex Gases & Technologies or not, you are always welcome to contact me for straight forward advise where it concerns gases or any gas related equipment. I look forward to hearing from you.
For more information on any of our services or products, contact Ron Perry, Sales & Marketing Director.