Breaking Seal Offs

[rbalex]

...If you really have a Class I, Division 1 location, I can not see permitting any one to enter the area without PPE suitable for the product as the IDLH for the products is equal to, or in a number of cases substantially less than the, LEL. I know that protection of people and selection of PPE for people is not the purpose of the area classifications, but based on the criteria used to classify the areas, the very fact that an area has been classified as a division 1 area should indicate that extreme caution is required to even enter the area.

This I have no problem with. I'm considering trying to formulate a Proposal for 70E that at least cautions that proper PPE has considerations often well beyond shock and arc-flash. Of course, that's true even in unclassified locations. I faught several Code cycles to get the term nonhazardous removed for a similar reason. (Just 'cause it ain't Classified, don't mean it's not hazardous)

I'll confess to a reluctance to use electrical area classification for anything other than selecting electrical equipment and installations because of experiences I've had receiving pressure (often extreme) to reduce or eliminate it where it was used for other purposes (fire proofing, roadway routings, etc). Nevertheless, your point is well taken and times have changed; at least with major users, so I'm more open to the idea of a "general" area classification document that incorporates more than electrical uses. Indeed, that is the fundamental IEC approach where the document is used for everything already mentioned, as well as major equipment layout and review of non-electrical ignition sources.

 

[bobgorno]

I agree, the whole "hazardous" and "classified" definition scheme needs clarification.

When assessing a hazardous area it is always nice to know odor threshhold, IDLH, OEL, STEL, LEL. (With the holiday parties fast approaching, add DWI and DUI levels to your ethanol hazardous knowledge base.)

A good rule of thumb is, IDLH is never higher than 10% LEL, but in the case of many solvents can be much lower than 10% LEL (example acetic acid @ 50 ppm). If a plant has closed process systems and enough ventilation to meet industrial hygiene criteria, it probably is not Div. 1.


Some facilities can not spell EH&S if they have not been designated as a PSM facility. Labs and "Pilot" Plants can be scary. I try to keep electrical contractors informed of chemical dangers when I do an EAC assessment even though HAZCOM is not in my scope. As an electrical contractor you should make sure your crews are extra vigilent of toxic materials whenever you send them to an electrically hazardous (classfied) site.

Flammable liquids are not the only danger. Watch out for ceiling spaces with combustible or toxic dusts. It is not enough to know that the MSDS's are available for review.....You need to actually READ them.

BobG

 

[DAWGS]

let us know, please

Winding down on this project. The seals were never poured so we did not need to use the vinegar.

 

[fishin' electrician]

The seals were never poured so we did not need to use the vinegar.

I find that is the case, more often than not, probably around 60/40.

Sometimes it's better to be lucky than good:grin:.