An important piece of equipment used in scuba is also one of its smallest. The o-ring creates an airtight seal between your air tank and your regulator, ensuring steady air flow without leakage. O-rings are manufactured from several types of materials with different degrees of resistance to the elements.
Hydrocarbon-Based Synthetic Rubber
O-rings made from this product are referred to as NBR or Nitrile. Most rental equipment tanks use Nitrile o-rings because they are economical. Nitrile is resistant to oil and acid but is not resistant to or compatible with oxygen. Saltwater, UV rays and gases can deteriorate the composition of these rings, leading to more frequent need for replacements.
Fluorocarbon Elastomers
Fluorocarbon elastomers, or FKM, are superior to Nitrile in that o-rings made from FKM won't break down under the same conditions that rings made of Nitrile do. FKM o-rings also provide good resistance to chemicals and oil.
Polyurethane
Polyurethane, or PUR, o-rings, are another alternative to Nitrile. They are resistant to abrasion but are sensitive to UV rays and may break down beneath sunlight over time.
Ethylene Propylene Diene Monomer
O-rings made of EPDM are among the most popular because of the product's perceived safety for use with air systems. In addition to possessing all of the resistance properties of FKM, EPDM is heat-resistant, weather-resistant and odor-free.
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