Class 1 Division 2 energized Equipment During "high" gas"

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natfuelbill

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In a C1D2 classified hazardous area, are there any (1) codes, (2) standards, or (3) otherwise, that discuss the power to C1D2 equipment remaining energized, or not, during an event when an explosive mixture of gas is present?
 
Is it normal or frequent to have this event? If it is frequent, due to maintenance or operations, even if it is considered abnormal, you might really be Div. 1. Without knowing all of your particulars, it's hard to discuss.

You don't have to de-energize power to Div. 2 equipment just because of an infrequent leak. And you can't install Div. 2 equipment where you have frequent leaks.
 
natfuelbill said:
In a C1D2 classified hazardous area, are there any (1) codes, (2) standards, or (3) otherwise, that discuss the power to C1D2 equipment remaining energized, or not, during an event when an explosive mixture of gas is present?
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I would say (3). Common sense would say that if you KNOW there is a hazard, that you would do something about it.
 
Revised question.

In a C1D2 classified hazardous area, are there any (1) codes, (2) standards, or (3) otherwise, that discuss the power to C1D2 equipment remaining energized, or not, during an event when measurable levels of gas is present? At a level below the LEL, action to limit and reduce the increase of concentration occurs before the level reaches an ignitable level.

Does gas detection equipment need to be installed C1D1? If so, why?
 
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natfuelbill said:
Revised question.

In a C1D2 classified hazardous area, are there any (1) codes, (2) standards, or (3) otherwise, that discuss the power to C1D2 equipment remaining energized, or not, during an event when measurable levels of gas is present? At a level below the LEL, action to limit and reduce the increase of concentration occurs before the level reaches an ignitable level.
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If one were to put gas detection equipment in a C1D2 area, there is nothing to prevent one from interlocking it with some piece of equipment or pieces of equipment to shut it down in the event a leak is detected. In fact this is not unusual. For the purposes of electrical safety, it is not required.

natfuelbill said:
Does gas detection equipment need to be installed C1D1? If so, why?
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In a C1D1 area, it is assumed there will be with some regularity a hazardous condition and the electrical apparatus is selected and installed in such a way as to mitigate that hazard.

It is very common to have gas detection equipment for other reasons. If you have a leak, you really want to know about it. Also, many compounds that are flammable, are also hazardous to human health, so you would want to know about it.
 
natfuelbill said:
Does gas detection equipment need to be installed C1D1, in a C1D2 area? If so, why?
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There are many reasons you may do it. There are some reasons you shall do it. It depends on the circumstance. For example, I think D.O.T. requires it in remote pumping or compression stations. Many D.O.T and non-D.O.T. compression stations use it as a way of declassifying from D1 to D2 for inadequately ventilated compressor areas.

Many owners require it for personnel safety monitoring. For example most solvent or alcohol IDLH exposure levels are 10% LEL or less.

Take a look at API RP500 and NEC 500.7(K) for some guidance.
 
natfuelbill said:
Does gas detection equipment need to be installed C1D1, in a C1D2 area? If so, why?
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There is no need to install gas detection equipment in a classifed area for the purposes of the NEC. There may well be requirements to do so. A pretty common one I run across is H2S detection. has nothing whatsoever to do with the NEC, but the stuff is nasty, and quite dangerous to human beings.
 
Ultimately, there is no requirement to automatically remove power in a Division 2 location. However, there are basically two elements to consider: what was the basis for the Division 2 classification in the first place and what was the cause of the release?

If the location would have been Division 1 but for some auxiliary means for reducing it to Division 2, such as purging/pressurizing or gas detection then typically an alarm is all that is needed. If the release is catastrophic, see API 1.2.1b.
 
Are there other documents that might help me understand this better?

The API-500 1.2.1.b is prefaced that API-500 are beyond the scope of itself.

Thank you very much for your input,
Bill
 
If a location has been properly classified, there is no requirement to de-energize electrical equipment in Division 2 applications for incidental releases.

If the location has been classified as Division 2 because of auxiliary systems (ventilation, purge/pressurization, gas detection, etc.) then there may be a need to respond if the auxiliary system fails. However, it is still unlikely that the response must be [immediate] de-energization.

If the electrical installation is otherwise environmentally stable, i.e., the environment does not actively attack the installation during a release, then the only need is to deal with arcing, sparking and heat producing (ASH) elements of the installation. This is exactly what Division 2 does. If the environment DOES attack the installation, it should have been classified Division 1 – no matter what the auxiliary systems do. See Section 500.5(B)(1)(3).

Edit Add: Added [immediate]
 
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Class 1 Division 2 energized Equipment During "high" gas"

natfuelbill said:
In a C1D2 classified hazardous area, are there any (1) codes, (2) standards, or (3) otherwise, that discuss the power to C1D2 equipment remaining energized, or not, during an event when an explosive mixture of gas is present?
Click to expand...
I have a situation on a compressor station quite similar. The monitering alarms are not set to such down anything if the enclosures become gas contaminated.
 
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