Hazardous Area Certificate for Mechanical Equipment


Thread Starter



We are installing an actuated gate valve in a Gas Plant which operates with high pressure hydrocarbon gas rather than instrument air.

I wonder if we need to have a hazardous area certificate for the actuator?

The reason I am asking this is that normally hydrocarbon gas is inside the actuator which makes it a ZONE 0. Immediately next to the connections there is ZONE 1 as well.

I understand the gas inside will be far above the UEL (Upper Explosive Limit) so even in case of a spark it will not explode, however if for any reason there is a leakage at the connections, there will be enough air just next to it.

The actuator is rotary by nature and has a turbine and a series of gears.

Is there any particular code requirements (e.g. as per ISO/IEC 80079 or maybe ATEX)to comply with and have certificate for?


Bruce Durdle

If the actuator contains a flammable gas that could leak into the atmosphere, it must be treated as a potential source of release during area classification. In parts of the world operating under ATEX rules, as set by the EU, there are requirements for certification for ANY equipment that could be a source of ignition - including non-electrical items such as you describe. But for the rest of us, the codes haven't caught up with the fact that most ignition sources are non-electrical.

But in any case you need to carefully consider the possibility that the valve and its mechanism could act as an ignition source, just as a matter of good practice and engineering ethics.