Ethanol in cleanroom: Class?

[sarjahe]

When I was 'in the trade', umpteen years ago, the most explosion proof work I ever did was probably a forklift refueling station. So I know the classification exists just not a lot more.

I have been informed that 'they' want to place three ethanol recirculation systems in our ISO 7 cleanroom. All together they will hold 50 gallons. 15 gallon drums, on carts with secondary containment, will transport the ethanol in and out of the cleanroom. The smallest system is enclosed in a SST cabinet using gravity transfer. The larger systems use pumps, tubing and so on. One has secondary containment. The other does not (engineering decision). This is R&D so the systems are designed here by fresh from school engineers.

What will the presence of these systems do to the code classification of the cleanroom? Does every machine and hook-up in there now need to be NEMA 7X? Does the air circulation provide sufficient fume removal to escape explosion proof requirements? I wish I could proceed from the ignorance is bliss prospective like our engineers, but alas I know just enough to be worried. Enlighten me please.

 

[megloff11x]

Sometimes labs are exempt from the hazardous location requirements, which they shouldn't be given the propensity for life, limb, and property threatening schemes to increase in both frequency and danger with education level.

If the containers are and stay sealed in normal operation, you are usually Division 2 which is MUCH less of a headache than Division 1 (everything in the open to ignite).

I would start by analyzing what will cause these to ignite and start a conflagration, and how can it be stopped, rather than start with the code. The code can still give you a set up that won't protect against all circumstances.

Many of my gray hairs come from a lab where they had an acetylene welding tank piped through a sparky roughing pump, and ran it this way for over a year until an incurable leak developed and they called in outside help.

Then again they did the first Nuclear reaction under a football stadium in the middle of Chicago. Imagine if that had gone badly given the ignorance of the process the first time...

Get the NEC, and I think labs are NFPA 45, and work from there. Also find your local and state codes. And then think what will go awry and how can I prevent it.

OSHA might give you advice too. Better to ask them before than they ask you after...

Matt

 

[petersonra]

I would start by analyzing what will cause these to ignite and start a conflagration, and how can it be stopped, rather than start with the code. The code can still give you a set up that won't protect against all circumstances.
Matt

I would start by hiring someone competent to make these determinations. Guessing and hoping are not in my design philosophy.

 

[muskiedog]

OSHA 1910.016 flammable and combustibles
OSHA 1910.1450 laboratory

The quantities you have may fall under the exceptions or would not require additional upgrades to equipment. You are alloted so much in a use area that would not require explosion proof electrical equipment.

I helped design the storage facility for a large printing company. Product in use is not goverend quite the same as product in storage.
This will help but you probably should talk with the local fire marshall and get their input on how they would classify it.

 

[rbalex]

It is difficult to determine from your description what your exact needs will be. Depending on your ventilation system, it is indeed possible that you would need a Division 1 installation. Clean rooms tend to want to minimize airflows to keep filtering requirements down. Once you open containers in the facility the nature of the ventilation is a critical criterion.

NFPA 45: Standard on Fire Protection for Laboratories Using Chemicals is your best start. You may be able to limit the effects with properly designed hoods, dispensing methods, ventilation methods, etc.

 

[megloff11x]

I would start by hiring someone competent to make these determinations. Guessing and hoping are not in my design philosophy.

My Uncle retired from Arson investigation and opened his own consulting business for insurance and lawsuits, and I got to know several related experts in my travels. Just because it is UL listed or met code, doesn't mean you are out of the woods. Many designs or layouts pass muster but still caused the fire. The code is the minimum. And in many cases, some extra mandated features are useless boilerplate, and some of what the code says won't help your unique circumstance. You not only need to pass the checklist, you need to prevent a fire.

You can bring in OSHA for free (as long as they don't see other violations on their way through). You can also bring in the local fire marshall for free, and he'd like that as his boys will be the ones inside the building should the occasion arise.

If you want a really good inspection to identify faults, contact one of these fire investigation firms that insurance companies use as expert witnesses in lawsuits. The electrical inspector or contractor will follow a checklist and his own experience, which may be limited in the area of special occupancies. The arson investigators and expert witnesses for related lawsuits have seen it all. They've proven what causes and what prevents or mitigates fires.

I'm told that the local electrical inspector here many years ago was a fired bank clerk who married into the right politically connected family. On the other hand these expert witnesses would show how a UL listed coffee maker was grossly unsafe by design.

In the end you may want to consider not storing that much flammable material.

Matt

 

[petersonra]

It is difficult to determine from your description what your exact needs will be. Depending on your ventilation system, it is indeed possible that you would need a Division 1 installation. Clean rooms tend to want to minimize airflows to keep filtering requirements down. Once you open containers in the facility the nature of the ventilation is a critical criterion.

NFPA 45: Standard on Fire Protection for Laboratories Using Chemicals is your best start. You may be able to limit the effects with properly designed hoods, dispensing methods, ventilation methods, etc.

the clean rooms i have been in have a fair amount of air flow, but there is little in the way of air exchange. it is mostly recycled. whatever hazardous fumes got in the air would not be exhausted outside.

 

[rbalex]

I certainly don?t challenge your experience with the volume of air movement; I?m simply using the term most commonly used in NFPA 496 and API RP 500 with regard to ventilation.

Technically what we have here is a purging situation. The air flow is not only intended to move volatiles out of the enclosed area, but to dilute them as well.

I tend to be fairly liberal with area classification ? but you gotta draw the line somewhere and one of those lines is where the source of the flammable material is already inside the enclosed space.

 

[petersonra]

The clean rooms I have been in had air streams directed past work stations and then recirculated through a HEPA filter with little or no outside air brought in. The air velocity was noticeable but there was no effective ventilation.

There would have been little dilution effect because little or no outside air was brought in.