Dielectric Unions in Compressed Air Lines

No. Dry compressed air does not conduct electricity.

It depends on the facility requirements. If there is some reason that the facility needs to maintain separate ground or earth potentials, a dielectric union or inulation break would be necessary.

If this is the case, the client should dictate their requirements, I know of one that requires a double isolation break on incoming water, gas, and other metallic pipe services.

Ried,

Your refer to lines and come from outside services and they are most grounded for reasons of lighting... one zap to a water source and you could hit the whole city, so ground the line and problem goes away.

But the question was for compressed air, that is more often not an outside service and would not be required to be grounded.

Under ordinary circumstances, I would agree that compressed air lines do not need electrical isolation. But there are exceptions.

Electrified rail systems can have air operated track switches requiring air compressors and air lines. The electric rail systems can also have out of the ordinary grounding (earthing for people outside of the US) that require special electrical isolation of metallic structures, conduit and piping.

There can also be situations with special electronic labs within a facility that have special grounding requirements for a small area within a "normally" grounded building where special ground isolation is required.

I will agree that prehaps "99-44/100 %" of the time no dielectric union is needed on compressed air, but I have run into situations where it might be required. Check with the owner and/or specifier for the final requirement.

All of the above are good answers but miss the basic piping principle of connecting dissimilar materials.

To connect copper piping to iron (steel) requires the use of dielectric unions.The type/style used for basic piping and available nearly anywhere.

The more specialized dielectric requirements previously mentioned call for specialized fittings.

AB1