What Type of Gas Detector Should be Used for Offshore Installation?

The relevant criterion is "methane," not "offshore." (Nor "225 kva" nor "propane" for that matter.) A Google search returns gazillions of hits on "methane detector"; and you can subtract out any hits on "propane detector."

As the IBM sign used to say: THIM_K!

Hi, The term offshore Zone II is relevant as there is a standard that we need to conform for use in that location. On other locations, there might be different standards. What I'm questioning is, why is propane detector installed instead of a methane detector? Is it wrong installation or there is a specific purpose for propane detector? Using common sense, methane detector should be used since high percentage of natural gas is methane.

Maybe somebody screwed up? Welcome to the world of reality; it happens all too often.

for ONG, we usually use detronic pirecla for gas detector. It detects hidrocarbon gas. no need additional device to waste your money !

Since a gas which is lighter than air for example Natural gas or Hydrogen quickly rises up and accumulate under the roof, you will have to install the gas detector at the ceiling level, while a gas heavy than air such as propane will accumulate at floor level or in the cable trench below floor level accordingly the gas detector will be installed under the slab of the cable trench.

Common sense is that one detector is inadequate due to placement when you encounter both heavier and lighter gases.

In ATEX Zone ll methane falls under Group llA which is the propane group. Based on the ignition curves methane requires more voltage or current to ignite then say hydrogen. Group llC is the most dangerous group in the ATEX gas groups. If this is a NEC zone 2 area then methane falls in group D (per NEC). If you are looking to detect methane a propane detector should be ok. Propane has a lower ignition rating so it takes less energy to ignite than methane. Based on the codes both should work for ATEX zone ll group llA/ NEC class 1 zone 2 group D.

I'd be a bit more concerned about H2S myself.

Maybe two small pilot lights, one high and one low, will solve the problem all together.

It's Friday and near blizzard conditions here. I'm sorry, but found it hard to resist today.

No you should use the Methane detector, its a lighter gas than the propane one so if you detect it then the equipment should be stopped.

If you wait for the accumulation of a heavier or denser gas you might have already an explosive atmosphere present which is dangerous.

Propane stores more easily than methane, it's liquid at temperate zone ambient temperatures.

Is there any likelihood that propane is bottled/stored for emergency use in a genset and that the propane detector is installed to monitor the storage facility?