There are many kinds of fittings on the market for gas filters, including standard compression fittings, quick connect fittings, and push to connect fittings- to name a few. We are going to take a look at the different kinds of fittings and their applications:
Compression Fittings: These are the most common type of fitting found in GC labs. An inner ferrule is compressed or “swaged” around the tube by the outer compression nut. The ferrule is designed either to bite into the tubing, or compress without biting, depending on the manufacturer. They seal well and the seal can be broken and re-made several times, if it is not over tightened.
In general, order your gas purifier with stainless steel fittings if it will be used with stainless steel lines. Brass fittings are ideally used with softer copper tubing. If you want to use stainless steel lines with brass or nickel-plated brass fittings we recommend that you pre-swage the ferrule and tubing first, in a different stainless steel fitting. (Such as a union or “T” or any other fitting of the same tubing size.) Once it is swaged remove it from the steel fitting and install the tubing with compressed ferrule into the purifier’s brass fitting to create a good seal. This helps prevent flaring the fitting.
Quick Connect Fittings: have become more and more popular. They are used to provide a fast connection. They have two parts, a male and female, that screw together to provide a make-or-break seal. Once they are installed on the gas lines, replacing the filters is much quicker and easier than compression fittings because the Quick Connect pieces have O-ring seals and check valves to protect the gas line from outside contaminants when they are unconnected.
Brass Quick Connect fittings should be used with copper tubing and Stainless Steel Quick Connects should be used with stainless steel tubing
Metal Push to Connect Fittings: are used to connect plastic tubing. The connection is quick and easy to make, just insert the plastic tubing into the fitting until it “clicks”. They are not recommended for carrier gas lines because of potential oxygen and water permeation through the tubing.