Class 1 Div 1 Group A

[megloff11x]

Re: Class 1 Div 1 Group A

If this is all the case, why isn't every home in the country with natural gas or propane heat considered a classified location? There are plenty of fires caused by gas leaks.

The answer is in the fine print.

 

[prewrathrap]

Re: Class 1 Div 1 Group A

I assume they are classifying the room because of the welding gases ie acetylene. They are assuming that a cannister of gas can leak causing the vapor, hence the area classification.

Another concern would be if this room is tied to the regular building HVAC system and the gas could infiltrate the whole structure. Then possibly the whole building might be need to classified. However, in the residential and commerial buildings we do not classify natural gas, fuel oil, or other fuels that run furnaces, heaters, and toher applainces.

If they stand by the Class I Div 2 requirements then you will have to meet. The groupA and B in Cl I and Div 2 system is esentially explosion proof. Those are the only fittings that are listed for that service.There is a way around this method.

Simply put all bottles of actelyene outside and make a pipe header available throughout shop to use the welding gas. Add a LEL gas dtector that would sense the acetylene. This detector would be hard wired to a solenoid valve that would be located outside and shutdown header and bleed off all gas going into building. Also add an exhaust fan and provide about six changes of room air volume in hour time whenever the gas is sensed. This eliminates any need to classify building and provides a safety to keep from getting to lower explosive limit (LEL) of the acetylene gas.
By putting the gas outside you have esentially guaranteed that there can never be enogh gas to reach the LEL and with the gas sensor insures if a mishap does occur the system will shutdown and vent all gases to keep from getting to explosive concetration.

I do this all the time in analyzer building in the petrochemical industry.

Also look at the NFPA standards 399 and 499 if i remember the numbers correctly.

Hope this helps.

 

[bnd]

Re: Class 1 Div 1 Group A

prewrathrap
Thanks, will submit your idea to the powers to be and see if they approve.
bnd

 

[rbalex]

Re: Class 1 Div 1 Group A

Now remember I don?t believe the room needs to be classified at all, but I would have no problem relocating the bottles. However, it shouldn?t change the rationale for classifying the room, if necessary - there would still be a source of gas inside the room. In fact, with a header, it is likely there would then be even more potential leakage points in the mind of the ?classifier.? You would also have a 15 to 25? classified location outdoors that would need to be located away from inlet vents and other potential ingress points. This is all said in the vein of a consistent area classification technique - it's not a recommendation.

In this application, the rationale for a gas detection scheme should also be the same whether the bottles were indoors or out. In addition, this is not one of the three applications where the NEC recognizes gas detection as a protection method. Section 500.7(K) (1) would be the closest and it would still mandate a Division 2 installation. My personal opinion is gas detection automatically requires a Division 2 classification, else why are you attempting to detect gas. In 500.7(K) (2) the detection scheme actually defines the Division 2 ?boundary? from an outside source.

There is no current NFPA 399 and NFPA 499 refers to classification of dusts. The proper document is 497 as we have already mentioned.

500.7(K) Combustible Gas Detection System. A combustible gas detection system shall be permitted as a means of protection in industrial establishments with restricted public access and where the conditions of maintenance and supervision ensure that only qualified persons service the installation. Gas detection equipment shall be listed for detection of the specific gas or vapor to be encountered. Where such a system is installed, equipment specified in 500.7(K) (1), (2), or (3) shall be permitted.
(1) Inadequate Ventilation . In a Class I, Division 1 location that is so classified due to inadequate ventilation, electrical equipment suitable for Class I, Division 2 locations shall be permitted.
(2) Interior of a Building. In a building located in, or with an opening into, a Class I, Division 2 location where the interior does not contain a source of flammable gas or vapor, electrical equipment for unclassified locations shall be permitted.
(3) Interior of a Control Panel . In the interior of a control panel containing instrumentation utilizing or measuring flammable liquids, gases, or vapors, electrical equipment suitable for Class I, Division 2 locations shall be permitted.

 

[bnd]

Re: Class 1 Div 1 Group A

I feel like I'm in the twilight zone.
Everyone agrees that this room should not be classified. How do I stop this stupidity???
Where do I go to get info on why you don't classify a high school welding class room.Are there other schools in Calif. that have ran into this problem ?? Are there any Calif schools that have classified welding class rooms ??
Could use any input that is out there.I don't mind taking their money, but I just hate people in positions of authority that act like gods.
bnd

 

[rbalex]

Re: Class 1 Div 1 Group A

Have the lighting fixtures, receptacles and other equipment actually been specified or has it just been left up to the contractor to find?

Even for Division 2 they will be hard to find.

 

[bnd]

Re: Class 1 Div 1 Group A

Sorry been out of town working on gas stations.
The lighting fixtures were spec'ed. Exit and emg. lighting were spec'ed after I pressed for an addendum, but outlets, welding outlets and the fire system was left up to me. He had hanging cords for welding outlets in the middle of the room until I ?ed him, then he changed them to rigid conduits with EY,s & exposionproof outlets. Of course he didn't give product numbers or equals to pick from.
bnd