Will changing an electric motor fan rotation to counterclockwise make the fan......
- Thread starter MJM
- Start date
It's a enclosed motor but not an explosion proof rated for such .
Lot of real booth ex fans have belt drive external motors because explosion proof motors,fan housings are Expensive.
Fan blades are Always designed for a specific 'rotation'. Otherwise it would do "nothing".
So as long as it's spinning the correct rotation, doesn't matter which "direction" it's pointing.
But,
The Venturi housing it's in,effects everything. Even the blades position in the housing is critical. Generally centered or,1/2 in,1/2 out of the venturi outlet edge. Some are flush,some recessed. If you ever remove a fan blade,be Sure to make note or index mark It's position inside. Yeah it Does Matter.......
I've fixed hundreds of ac units that "someone" replaced the condenser fan motor on by just repositioning the fan blade. Or correcting the rotation.
As for turning the blade around,
No. It's designed for the way it is,that Venturi it's in creates an effect on the air and you'll be defeating it's purpose which is critical for proper operation.
I understand your idea and,
Would it work for the intention?
Yeah,but not quite what you're after.
If you plan on a real paint booth and seeing your not the type to half arse Anything,
Do it Right.....with the Right stuff.
My apologies for the wrong detail. It's a Venturi. Getting old sucks.....
Lot of real booth ex fans have belt drive external motors because explosion proof motors,fan housings are Expensive.
Fan blades are Always designed for a specific 'rotation'. Otherwise it would do "nothing".
So as long as it's spinning the correct rotation, doesn't matter which "direction" it's pointing.
But,
The Venturi housing it's in,effects everything. Even the blades position in the housing is critical. Generally centered or,1/2 in,1/2 out of the venturi outlet edge. Some are flush,some recessed. If you ever remove a fan blade,be Sure to make note or index mark It's position inside. Yeah it Does Matter.......
I've fixed hundreds of ac units that "someone" replaced the condenser fan motor on by just repositioning the fan blade. Or correcting the rotation.
As for turning the blade around,
No. It's designed for the way it is,that Venturi it's in creates an effect on the air and you'll be defeating it's purpose which is critical for proper operation.
I understand your idea and,
Would it work for the intention?
Yeah,but not quite what you're after.
If you plan on a real paint booth and seeing your not the type to half arse Anything,
Do it Right.....with the Right stuff.
My apologies for the wrong detail. It's a Venturi. Getting old sucks.....
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'68 Coronet R/T
Oldtimer
Personally I would put that fan with the other two and push the air through the booth.
You will be pulling air with no fumes and pushing it through the booth and out the other end. No concern for fire that way.
Here in Arizona, I live on 7 acres so neighbors complaining are not a concern. I use the garage door as the exit point and raise it just enough to keep the booth slightly pressurized by the incoming air.
It works very well. In fact, if I don't open the door before I turn the fans on, I can barely get it opened due to the pressure in the booth.
Overspray can be seen heading out of the booth right after leaving the spray gun. Booth completely clears in less than 30 seconds.
You will be pulling air with no fumes and pushing it through the booth and out the other end. No concern for fire that way.
Here in Arizona, I live on 7 acres so neighbors complaining are not a concern. I use the garage door as the exit point and raise it just enough to keep the booth slightly pressurized by the incoming air.
It works very well. In fact, if I don't open the door before I turn the fans on, I can barely get it opened due to the pressure in the booth.
Overspray can be seen heading out of the booth right after leaving the spray gun. Booth completely clears in less than 30 seconds.
MIke is totally correct...using open and non explosion proof motors can be very very bad, in dry or wet aplications. Place I worked at 2 paint booths per line running tubular axel blowers with 40HP motors, They had 5-7" of vacuum when the filters were clean.
This web site explains how to size a blower system for air turn over.
Number of cubic feet in room / Number of minutes per air change = Required C.F.M. Capacity.
John
MJM
Promoted Users
Very astute and detailed reply, thanks you.
If I understand what you telling me, will either if these plans "A" & "B" work for me?.........or am I still way off base?
To all, feel free to mark up the plans of what you would do from the layout of my garage.
Thanks gents, this is an area I'm definitely not well versed in.
Plan "A"
Plan "B"
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MJM
Promoted Users
MIke is totally correct...using open and non explosion proof motors can be very very bad, in dry or wet aplications. Place I worked at 2 paint booths per line running tubular axel blowers with 40HP motors, They had 5-7" of vacuum when the filters were clean.
This web site explains how to size a blower system for air turn over.
Number of cubic feet in room / Number of minutes per air change = Required C.F.M. Capacity.
I've got a SD20 that I built a 24x24 filter box for and also use the filter membrain over it. I plan on adding another. If I could do it all over again I'd use tube fan mounted on a pad outside the shop. Just my .02 worth.
John
That's the ticket for sure. It's not that I can't purchase those type of commercial paint booth exhaust fans, it just won't happen this year. I've already spent my allotted tool money for this year. I'd have to wait until spring of next year to get the car in finished paint.
It just pisses me off seeing those guys on Youtube who use a wall of Walmart 20" box fans and haven't blown themselves up. Hell at least my motor is fully encased. Last night I pulled the back cover where the motor is wired up so I could see the armature. Turned off the lights and fired up the fan to see if I could see any arcing. Didn't see any. I was going to do the same thing tonight and pull the start / run capacitor cover and see if it arcs in the dark. I was even going to go that extra mile and seal up all joints of the motor casing.
A man with a dream, then......................BOOM!
I've seen the same thing with people using old furnace open squirrel cage motors for exhaust fans. I'm not going to say that your fine doing it this way BUTTT....I'm guilty of doing it myself in the past using a enclosed motor and a filter media. A start or stop action on the motor and or the control is the most likely place for an arc to occur (unless the motor bearing are bad) so once you start the fan don't shut it off until the area is vented. Moving the start sw to the out going side of the fan would be best. Again just my .02 worth.
John
John
Chris_Hamilton
Trying to be the best me, I can be
Commercial Paint booth fans aren't explosion proof. The fans are non sparking though. TEFC is the most that is needed. Explosion proof simply means the motor/case itself is designed to withstand an explosion inside the case. Paint fumes in the grand scheme of things are much less dangerous than many other industrial chemicals/hazards. Gasoline vapor is far more dangerous. If paint fumes were super combustible, every time someone used an open flame or exposed element heater in a painting situation they would go boom..... The concentrations that it would take to ignite fumes with a spark would have to be really really high. Like letting a mixing cup full of reducer evaporate in a confined area like a large wood stove. Then it would be dangerous. But when you spray concentration of fumes never gets to that point.
Whitesnake
Newbie
AAE
Learner
22"Jenny
If you see Any electrical sparking Period from any A.C. voltage motor IT'S BAD news. Usually a loose connection or component or just wore out. Only exception is older belt drive type motors used a centrifugal switch internally to remove the Start winding at about 1/2 speed which are not around much now days but be aware of this if you encounter one. You can see the switch from the endbell openings where the power wiring enters. All the capacitors are enclosed and basically a non issue like your motor.
D.C. is a different motor all together, especially brush types which spark normally but a non issue with your thing.
Main thing I consider is the Door in. I prefer at the Exaust end so any debris will go straight out instead of across the Work with the air flow. Winter painting intake air will need to be considered, Crack the main o'head door or a window and you run what ever heater outside the booth in the garage which is what most of us hacks do eliminating any source of combustion inside the booth.
The whole 'fan' thing is a personal choice and we All likely have used inferior, hazardous contraptions for ventilation of our booth,guilty as charged,still am,and really, as long as whatever your using is in good condition and wired properly, does the job isn't a problem. But Shite Happens and the Insurance Adjuster will be Looking if it does.
D.C. is a different motor all together, especially brush types which spark normally but a non issue with your thing.
Main thing I consider is the Door in. I prefer at the Exaust end so any debris will go straight out instead of across the Work with the air flow. Winter painting intake air will need to be considered, Crack the main o'head door or a window and you run what ever heater outside the booth in the garage which is what most of us hacks do eliminating any source of combustion inside the booth.
The whole 'fan' thing is a personal choice and we All likely have used inferior, hazardous contraptions for ventilation of our booth,guilty as charged,still am,and really, as long as whatever your using is in good condition and wired properly, does the job isn't a problem. But Shite Happens and the Insurance Adjuster will be Looking if it does.
We used EXPL motors on units that were mounted in the booths / in the exhaust flow. All TEFC we used were externally mounted running the tubular axial units which were the most common. I'd go with plan B on your layout, Just close the door to the top of the fan and block the sides off.
John
John
shine
Member
i've watched old painters smoking while painting. never in 50 years have i witnessed a booth explosion. but i have seen dumbasses with oil drain pans full of thinner burn down shops. that and throwing rags in the trash. i throw rags on the floor and then throw away a few days later.
'68 Coronet R/T
Oldtimer
I built a large plenum box with squirrel cage motors mounted outside the booth and on top of the plenum. They produce about 2400 CFM each and I have 4 of them at present. Once on, they stay on until the booth is clear of fumes, which doesn't take long at all. This is good for spraying clears that Barry recommends shutting the fans down while they flow and flash.
Looking at the drawings above, the small area of air flow will must likely cause recirculation problems. This is why I ended up doubling the size of my filter bank, to create more of a wall of air moving through the booth.
The air flow being concentrated will hit the vehicle and being curling off to the sides and top, thus caring overspray back toward the front of the booth. It will then be drawn back into the air flow and sent back over your vehicle.
I am not design expert but did read up on booth airflow requirements and designed my homemade booth to exchange all the cubic feet of air it contains, about twice per minute.