Hazardous Location Heating

[dema]

I am to write a report on how to get a 60'x60'x20' pole barn used for paint storage up to code. It has lighter than air and heavier than air chemicals. The trouble I am having is the heating.

Is there a reason that I cannot use an explosion proof filtered intake and exhaust to bring in heated air from another space?

Do you know if a filtered intake counts as a penetration in terms of NFPA 497?

Would I be able to duct straight to that intake? Is that an allowed method?

Thank you for your help.

 

[gadfly56]

I am to write a report on how to get a 60'x60'x20' pole barn used for paint storage up to code. It has lighter than air and heavier than air chemicals. The trouble I am having is the heating.

Is there a reason that I cannot use an explosion proof filtered intake and exhaust to bring in heated air from another space?

Do you know if a filtered intake counts as a penetration in terms of NFPA 497?

Would I be able to duct straight to that intake? Is that an allowed method?

Thank you for your help.

I used to work for Hercules at their gunpowder plant in Kenvil, NJ. All the buildings were heated using low pressure steam radiators. You could also opt for baseboard heat I'm sure.

 

[Tony S]

I’ve worked with explosive atmospheres (natural gas and solvent based printing inks). I would go with gadfly’s suggestion of LP steam or plain old hot water radiators.

What other protection has been included for lighting and switching?

 

[dema]

Listed devices

Listed devices

We will use listed devices for lighting, receptacles and switches with threaded steel conduit and so forth. It is just the heating that had me befuddled. I'm electrical - not mechanical and my mechanical hasn't done hazardous.

 

[kwired]

There are hazardous location unit heaters out there - just do a Google search and you will come up with quite a few.

Is there such a filter that can filter out the hazardous material and still let enough air flow through to be very effective if you were to duct to a non hazardous location heating unit outside the space?

I like the steam ideas that have been presented and will add any forced air steam heater still needs blower motor designed for the area or located outside the area somehow. The blower itself also needs to be made from non sparking material - steel blower will typically be a no - no.

A heat pump would also work and can heat or cool, but again needs to be specially designed for the location as far as controls, blower motors, non sparking blower materials, there may be such products out there for this application.

 

[Tony S]

We tried an external filtered air heater for one of the printing ink stores. The filters and flashback slam shuts were a PITA.

Steam or hot water radiators require no electrical supply and work reliably. If forced air is needed then flashback slam shuts and vents are needed.

This is in an area where specialist advice is needed. No disrespect to members but this is not a topic for an internet forum.

 

[kwired]

We tried an external filtered air heater for one of the printing ink stores. The filters and flashback slam shuts were a PITA.

Steam or hot water radiators require no electrical supply and work reliably. If forced air is needed then flashback slam shuts and vents are needed.

This is in an area where specialist advice is needed. No disrespect to members but this is not a topic for an internet forum.

I agree a specialist is needed. I disagree that we shouldn't talk about it here - it is good learning material just like most other discussions are.

 

[rbalex]

I may have picked up on this a bit sooner if it had been posted in the Hazardous (Classified) Locations forum.

Electric heating isn't exceptionally difficult. See Section 501.135.

With regard to NFPA 497 all penetrations count, but the direction of air flow does too.

I agree steam or hot water is often better.

 

[Tony S]

As I said in #6 we tried filtered warm air for one ink store. It was more trouble than the other four stores put together. Common sense finally made us go to a hot water system in line with the others.

Other parts of the plant were interesting. Solvent based inks need heat to stabilize them and drive off the solvent. Normal practice was to burn the exhaust solvent fumes in a heat exchanger to heat the print drum. A lot of heat went to waste.
We used a separate natural gas heat exchanger and drew off the solvent fumes to feed a recovery plant. Raw ink has a high % of solvent to keep it in a paste form, to make it the correct viscosity for printing a lot more solvent is added.
We recovered almost 100% of the raw and added solvent. Most print shops have to buy in solvent, we exported it.
The recovery plant and anywhere near the press print drums were all <Ex> 0 or 1 zones (NFPA70 Class 1 Div 1 or 2)


If ever you wonder what happens to toxic waste printing ink or even the dreaded PCB (poly-chlorinated biphenyl) look no further than a bag of cement.
That was my next job.
PCB needs 1750C to destroy it, where better than as a supplementary fuel for a cement kiln?