Question about CID2 Area.

[Jose Machin]

Hello,

I have been going through the code, and I still have a doubt about a specific issue.

We are setting up a filling station for HFC-152a, which is a flamable gas.
We are installing everything explosion proof in the CID2 zone, the pump motor, switches, scale, but we have an special equipment that is to recover gas after the filling is done.

This recovery machine, can be installed in the unclassified area, and used with flexible hoses or rigid piping that can extend to the clasified area.
Is this usage approved by the NEC and NFPA codes?

Any help is greatly apreciated.

 

[Strathead]

Hello,

I have been going through the code, and I still have a doubt about a specific issue.

We are setting up a filling station for HFC-152a, which is a flamable gas.
We are installing everything explosion proof in the CID2 zone, the pump motor, switches, scale, but we have an special equipment that is to recover gas after the filling is done.

This recovery machine, can be installed in the unclassified area, and used with flexible hoses or rigid piping that can extend to the clasified area.
Is this usage approved by the NEC and NFPA codes?

Any help is greatly apreciated.

I don't completely understand your question, but I can also offer some information that may help you to understand or clarify your question.:

You probably know, but NEC is an NFPA code. The NEC doesn't determine what areas are classified. NFPA 497 offers guidelines that are used for this. The NEC does, for simplicity, set rules for certain classified areas like gas stations, fuel tanks, paint booths, to make the installations uniform and compliant with the intent of 497.

Now to your question. If I understand it some, the recovery machine and the hoses attached may be deemed incapable of creating an atmosphere around it that has the proper mixture of oxygen and gasses to allow ignition. If so, then wiring to it or around it is not in a classified area. When you pipe electrical conduits through the classified boundary then you must follow the NEC for all piping. In a Class 1 division II area this is not always rigid conduit etc, it is often controlled via ventilation.

Hope this helps.

 

[Jose Machin]

I don't completely understand your question, but I can also offer some information that may help you to understand or clarify your question.:

You probably know, but NEC is an NFPA code. The NEC doesn't determine what areas are classified. NFPA 497 offers guidelines that are used for this. The NEC does, for simplicity, set rules for certain classified areas like gas stations, fuel tanks, paint booths, to make the installations uniform and compliant with the intent of 497.

Now to your question. If I understand it some, the recovery machine and the hoses attached may be deemed incapable of creating an atmosphere around it that has the proper mixture of oxygen and gasses to allow ignition. If so, then wiring to it or around it is not in a classified area. When you pipe electrical conduits through the classified boundary then you must follow the NEC for all piping. In a Class 1 division II area this is not always rigid conduit etc, it is often controlled via ventilation.

Hope this helps.

I know that NFPA 497 is used for classification of areas, and based on that I classified that area as C1D2.

The question is the following:

Scenario 1
If the machine has non permanent connections like threaded connections (consider that the connections are at the machine), then I have to consider that a leak can occur, right? In that case the machine has to be explosion proof.

Scenario 2
If I installed the machine in the unclassified area, and run permanent rigid piping with permanent seals, like soldered cooper piping. I can safely say that the can not be any leaks, so I can use a non explosion proof machine.

 

[Strathead]

I know that NFPA 497 is used for classification of areas, and based on that I classified that area as C1D2.

The question is the following:

Scenario 1
If the machine has non permanent connections like threaded connections (consider that the connections are at the machine), then I have to consider that a leak can occur, right? In that case the machine has to be explosion proof.

Scenario 2
If I installed the machine in the unclassified area, and run permanent rigid piping with permanent seals, like soldered cooper piping. I can safely say that the can not be any leaks, so I can use a non explosion proof machine.

In my unprofessional opinion, no not right. The pipe can still break. Class 1 div II includes areas where gasses are not normally present, but may become present in concentrations that can ignite. So it is really a question of whether those gasses will be available in those concentrations under any fault condition.

 

[rbalex]

A few comments:

• Articles 511 to 516 do not apply to this installation so another standard is needed to classify the location; NFPA 497 is fine.
• When NFPA 497 is used as the basis for classification, read the text as well as reviewing the diagrams. It isn't that long - read all of it.
• When you read the text, "closed piping" means piping with no ordinary avenues to atmosphere such as vents, relief valves, or threaded piping. Closed process piping (hoses or rigid) do not necessarily create a Classified location.
• For a "break" in the piping, see NFPA 497, Section 1.1.4 (there are bigger problems than the electrical installation can handle)
• Division 2 does not necessarily require explosionproof equipment.