exhaust fan

[dan19403]

a customer is constructing an area in their basement for refurbishing furniture, etc. They plan on using stains, varnishes, paints etc.

They wish to have a ducted exhaust fan to remove the fumes of their work. I believe that they require an explosion proof exhaust fan.

There are open joists in which I believe that a fan can be mounted ant ducted to the outside of the house.

My local supply house is having a difficult time locating a fan that will fit my application.

There was some contention that I do not even need to pipe in an explosion proof fan -- another electrician informed the customer that a standard Nutone QT300 (300cfm) would be safely sufficient -- i don't agree do to the fact that it is located in a basement, and that flammable vapors will be going throughout the fan mechanism and motor assemby & housing. The nearest recepts. and lights are located at a minimum of 6' away from the "work area" ( piped in to 24" above the floor ).

I'd appreciate some feedback and opinion.

Thanks,

Dan

 

[dan19403]

Re: exhaust fan

note:

ceiling height 7.5'
8" joists

 

[noxx]

Re: exhaust fan

Well, right off the bat, putting a finishing shop in the basement just isn't the best idea I've ever heard but customers will be customers..

The best route here is to contact an HVAC contractor regarding a positive-pressure ventilation system in which air is mechanically forced into the area and exits through an exhaust duct due to the resulting pressure. In this arrangement the fan is located outside the area and the positive pressure duct will not in normal operation collect an ingitable quantity of vapor. Whether or not this installation falls under class 1 div. 1 depends entirely upon on the type and quantity of products being used, I won't pretend to be an expert on wood stain.

If you do go with a normal ventilation system the fan motor should be protected, I can't offer any advice on where to find one but be prepared for a relatively ridiculous cost when you do. Good luck.

-Noxx

 

[Guest]

Re: exhaust fan

One comment about explosion proof fans - the motor itself does not necessarily need to be sparkproof. There are explosion-proof rated fans that are simply sparkproof squirrel cage fans where the motor is mounted external to the ducting. The motor's simply not inline with the exhaust fumes. Small blowers are available in 12" sizes and should fit this application.

If the customer's basement also houses a boiler, furnace or gas/oil-fired water heater - you should offer to install a CO2 detector near that equipment. That way, when they fire up the exhaust fan and suck all the CO2 down their chimney flue, they'll at least get a warning about it.

I'd predict that the exhaust fan won't get used much more than a few times. Unless the customer is installing a spray booth with filters or some other setup to filter the incoming air, the ambient dust from the basement is going to contaminate their finishes. That will end the use of the exhaust fan.

What are you doing for explosion proof lighting?

 

[don_resqcapt19]

Re: exhaust fan

They need to look very close at this. The flammable vapors of most of these products have a vapor density greater than one and will stay near the floor. Often they will travel to the area of the furnace or water heater pilot light and ignite. This if a far more likely cause of an explosion then the electrical equipment.
Don

 

[electricmanscott]

Re: exhaust fan

KABOOM!!!!!!

 

[bennie]

Re: exhaust fan

Not only the fire hazard, but damage to the breathing system is very likely.

I should send them my lung X-Rays to show what happens when a person is not careful.

 

[sparkmantoo]

Re: exhaust fan

it seems to me that no matter how much you tell a customer that what they are trying to do is not safe, they will in turn and go around your back so to speak and install something anyway. i've seen electricians paint their cars and smoking cigaretts at the same time. people do what they want to do, the only thing that we can do is tell them that it is unsafe and instruct them in the proper way to do these things so they won't blow themselves up

 

[dan19403]

Re: exhaust fan

Originally posted by rlrct:
One comment about explosion proof fans - the motor itself does not necessarily need to be sparkproof. There are explosion-proof rated fans that are simply sparkproof squirrel cage fans where the motor is mounted external to the ducting. The motor's simply not inline with the exhaust fumes. Small blowers are available in 12" sizes and should fit this application.

If the customer's basement also houses a boiler, furnace or gas/oil-fired water heater - you should offer to install a CO2 detector near that equipment. That way, when they fire up the exhaust fan and suck all the CO2 down their chimney flue, they'll at least get a warning about it.

I'd predict that the exhaust fan won't get used much more than a few times. Unless the customer is installing a spray booth with filters or some other setup to filter the incoming air, the ambient dust from the basement is going to contaminate their finishes. That will end the use of the exhaust fan.

What are you doing for explosion proof lighting?