Area Classification 1

[eepedude]

I had someone at work ask me why we classify plants, processing facilities, etc for Class 1 Div 2, etc, where gas has the potential to leak, but yet, we don't classify our homes around gas stoves and gas water heaters.

Anyone have any thoughts on this.

Thanks

 

[Ahr35181]

eepedude,

For the very same reason we don't area classify the works kitchen (containing gas cookers)...Risk / cost balance.

Alan

 

[3winding]

You do not necessarily have to classify your processing facility. By conducting a fugitive emissions study it can be shown that what might have been a Zone 1 can be classed a Zone 2 or what was classed a Zone 2 can now become non-hazardous. API 500 and API 505 are a good reference.

 

[3winding]

eepedude,

Further to my last comment, this applies basically when referenced to the Canadian Electrical Code. It is up to the engineer to determine what the classification of an area shall be. If she/he determines that it does not need to be classified, then the engineers classification shall apply. Conducting a fugitive emissions study is one way of accurately determining the classification of an area.

 

[eepedude]

Thanks,

I agree about using API code. What I was really looking for is why inside homes we don't classify equipment or surroundings such as gas stoves and gas water heaters. If you think about it, gas has more "leakage" potential there than it does at at process plant.

But what I told the guy at work, that it really comes down to what someone mentioned earlier.... RISK/COST basis.

 

[rbulsara]

Also many codes are adopted based on history of incidents, in fact that is how electrical and fire codes originated as accident reviews demanded some action.

For example, percentages of accident involving a gas explosion in residential places may be much lower than those involving electricution or fires due to faulty electrical work.

Many code requirements in modern days are also dictated by Insurance companies which in turn are based on the claims they see.

Plus cost/risk factor is always there.

 

[jbartos]

Comment: As a rule of the thumb, the industry Environmental Classifications tend to be exaggerated in some cases; however, the households environments, e.g. old oil burner leaking CO, are grossly environmentally underestimated Environmental Classifications. I recommend keeping a couple of CO detectors activated at home.

 

[EldonP]

I don't have my codebook with me so I can't tell you which of these reference it but either 10.15.1.1 or 6.5.9.2 in API 505 state that there is no need to classify combustible materials that are in a building for the purpose of combustion. Basically if you're planning to burn it anyways you dont have to classify it.

 

[jbartos]

Suggestion: Visit

http://www.come2meet.com/apec/cd/05...perience with Hazard Communication Part 2.ppt

for a high level presentation

 

[GOTWW]

Do not forget about the metric system "zones". The IEC version. Hopefully they are better that the undersized motor starters, that we have to replace after the 1-year construction warrenty.

 

[njengr1]

As a former member of the API 500 /505 committee I can tell you these standards are based on keeping the oil business safe. The NEC has adopted these standards in 70A and other documents. If the Auhority Having Jurisdiction feels a particular site needs a hazardous classification, then the NEC sections for hazardous installations apply.

The spirit of these documents is to keep an "electrical ignition" from occuring. Many areas with an open flame will be unclassified (for electrical) because the flame will ignite any gas before an electrical ignition can occur. (Like around the water heater in the basement.)Thus, no special electrical gear is required.

 

[rmw]

njengr1,

I often get asked for explosion proof enclosures and motors on boilers, heaters, and other devices with open flames. Funny how it seldom occurs to some what problem you are really trying to solve by classifying an area, and using explosion proof equipment.

rmw

 

[GOTWW]

Ah yes, cool the vapor flames and contain the exposion inside the box that the is the source of the ignition,

does not make much sense when open flames are aboundent in the general fcinity does it?

 

[jbartos]

Suggestion: In addition to the XP enclosure, the corrosion is also to be considered to have the enclosure XP corrosion resistant, e.g. NEMA 4X.

 

[EldonP]

I wasn't totally accurate in my previous post, my apologies. To clarify, API RP 505 section 6.5.9.2 states:

"Adequately ventilated locations surrounding equipment that has continuous flame sources (eg. unprotected fired vessels and flare tips) need not be classified solely by reason of the fuel gas being considered as a source of release.
Note 1: it may be prudent to classify portions of these locations. For example electrical equipment may be exposed to flammable gas during a purge cycle of a fired heater or furnace.
Note 2: The lack of classification around unprotected fired vessels and flare tips does not imply the safe placement of fired vessels and flare tips in the proximity to other sources of release because unprotected fired vessels and flare tips arethemselves sources of ignition. The decision of whether or not it is safe to install the unprotected fired vessel or flare tip at the location is outside the scope of [RP 505]".

 

[robertb]

At the same time we do not require 3'clearance in front of electrical receptacles.

 

[jbartos]

Suggestion: NFPA 70-2002 National Electrical Code (NEC) describes the hazardous areas in Article 500 Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2