I have been painting automobiles off and on for 30 years . Planning on building a 40x40 shop and frame up and sheetrock an area 14 x 26 to paint in .
Could you please recommend the lights and fan y’all would install ?

Let's assume that you plan on making an end draught booth, that is one where the air comes in at one end and the exhaust is at the other end. You could also have the air intake in the ceiling at the opposite end to the exhaust which would be at floor level, in which case you'd have a semi downdraught booth, which is better than an end draught. In either case the calculations will be the same as are detailed below.

If you're thinking about a side or full downdraught design then the calculations are different and you're likely to need 2-3 times the fan capacity for a start.

So,
14' = 4.3m
26' = not relevant
Assume 9' = 2.7m high

You need to move a front that is 4.3m x 2.7m = 11.6 sqm at a rate of 0.5m/s minimum. This is the rate required for safe evacuation of the isocyanate laden overspray and minimisation of overspray dropping back down on your freshly painted surface.

That's 11.6 x 0.5 = 5.8 cubic metres per second

5.8 x 60 (seconds/minute) x 60 (minutes per hour) = 20880 cubic metres per hour,

which converts to 737370 cubic feet per hour or 12290 cubic feet per minute.

So you need a fan, or fans, that have this capacity as a minimum. Ideally they should also be flameproof with the motor sealed or the fan belt driven by a motor out of the airflow.

The exhaust plenum should have a filtered area of around 2 square metres (or roughly the size of a standard door) and this should be as close to floor level as is possible. This allows you to make use of gravity which will have the overspray falling down as it travels along the booth. Putting the exhaust higher means you're fighting gravity and will have particulate drop out.

Intake filter area should be 1.5 to 2 times the exhaust. Don't be tempted to put fans on the intake - positive pressure booths are unsafe, especially when inside a shop and much less efficient that negative pressure.

The fan should bring the exhaust air through the filter into a plenum that is as deep, as a minimum, as the diameter of the fan and the face with the fan having sides sloped towards the fan to direct the air flow and reduce turbulence. For a typical unit with this kind of capacity that means about 600mm or, say, 24" and exhaust should then be pushed through a flue that ends above the roof line. Local regulations may determine the extent of this - for example, here in Australia, the flue must extend 3m above the highest point of the roof. Your regulations may be different.

Using drywall/sheet rock/gyprock for internal wall lining is cheap and easy but probably doesn't comply with any safety regulations, which require the internal lining of the booth to be flameproof or fireproof, i.e. usually metal sheet. Consider using insulated panel. If you use panel that is 50mm thick it will be self supporting and can take the ceiling weight without additional support while the ceiling will span your proposed width without extra support. Although more expensive than drywall, there is a big saving in not having to construct wall or ceiling frames, so the overall cost isn't that much more. If you can find some second hand panels then it may even be cheaper. Big savings in construction time and effort too.

These days LED lights are the best choice for output vs cost. Ideally there should be a row of lights along the wall to ceiling join along the length of the booth, angled at 45 degrees. How many lights you need depends on the quality/output of the lights you choose, but you should aim to have at least 700 lux at about 1 metre height in the centre of the booth. With the old fluorescents this meant banks of 3 or 4 tubes. Watch that many LEDs actually produce less light than fluorescents, so check specifications carefully. If possible also run a row of lights horizontally down each long wall, at about 1 metre height. This helps enormously when painting the side of a car.

Also be very careful about the colour of the LEDs. Colours in the range of 6000-6500K will change the apparent colour of the paint. Better to go for something around 5000-5500K which will render better. There are specific LEDs that are made to render colour accurately - usually a bit more expensive but really worth the extra cost.

exacly what i was going to say!
Jay D.

Depends on how extravagant you want to get. when built mine i was thinking of sheetrock taped and mudded. hanging the sheetrock up an 1 1/2 off the floor, then put white painted metal siding down to the floor over the sheetrock ( like they use on car ports ). put it on with the pattern going vertical (up and down). this way you could wash it out and or wet the floor if you wanted. the panels would reflect light real good.
Jay D.

One thing with the LED lights is to get the Frosted ones. Otherwise you'll be seeing spots everywhere you look - I made this mistake the first time around. And yes 5000k is the minimum for daylight type lighting.

This might help.... these were the last 10 pack of lights I picked up to fill in some areas of both my finish shop and stripping area. https://www.amazon.com/gp/product/B07BG ... UTF8&psc=1

Dont be fooled by the kelvin rating on a light, 5k-6k etc, you want to look at the CRI index and you want something 90 and above. CRI is color rendering index. a 5000k light can have a CRI of 80 and you will not be able to match colors under that light. so be careful in that respect to lighting and LED

NFT5 wrote:Let's assume that you plan on making an end draught booth, that is one where the air comes in at one end and the exhaust is at the other end. You could also have the air intake in the ceiling at the opposite end to the exhaust which would be at floor level, in which case you'd have a semi downdraught booth, which is better than an end draught. In either case the calculations will be the same as are detailed below.

If you're thinking about a side or full downdraught design then the calculations are different and you're likely to need 2-3 times the fan capacity for a start.

So,
14' = 4.3m
26' = not relevant
Assume 9' = 2.7m high

You need to move a front that is 4.3m x 2.7m = 11.6 sqm at a rate of 0.5m/s minimum. This is the rate required for safe evacuation of the isocyanate laden overspray and minimisation of overspray dropping back down on your freshly painted surface.

That's 11.6 x 0.5 = 5.8 cubic metres per second

5.8 x 60 (seconds/minute) x 60 (minutes per hour) = 20880 cubic metres per hour,

which converts to 737370 cubic feet per hour or 12290 cubic feet per minute.

So you need a fan, or fans, that have this capacity as a minimum. Ideally they should also be flameproof with the motor sealed or the fan belt driven by a motor out of the airflow.

The exhaust plenum should have a filtered area of around 2 square metres (or roughly the size of a standard door) and this should be as close to floor level as is possible. This allows you to make use of gravity which will have the overspray falling down as it travels along the booth. Putting the exhaust higher means you're fighting gravity and will have particulate drop out.

Intake filter area should be 1.5 to 2 times the exhaust. Don't be tempted to put fans on the intake - positive pressure booths are unsafe, especially when inside a shop and much less efficient that negative pressure.

The fan should bring the exhaust air through the filter into a plenum that is as deep, as a minimum, as the diameter of the fan and the face with the fan having sides sloped towards the fan to direct the air flow and reduce turbulence. For a typical unit with this kind of capacity that means about 600mm or, say, 24" and exhaust should then be pushed through a flue that ends above the roof line. Local regulations may determine the extent of this - for example, here in Australia, the flue must extend 3m above the highest point of the roof. Your regulations may be different.

Using drywall/sheet rock/gyprock for internal wall lining is cheap and easy but probably doesn't comply with any safety regulations, which require the internal lining of the booth to be flameproof or fireproof, i.e. usually metal sheet. Consider using insulated panel. If you use panel that is 50mm thick it will be self supporting and can take the ceiling weight without additional support while the ceiling will span your proposed width without extra support. Although more expensive than drywall, there is a big saving in not having to construct wall or ceiling frames, so the overall cost isn't that much more. If you can find some second hand panels then it may even be cheaper. Big savings in construction time and effort too.

These days LED lights are the best choice for output vs cost. Ideally there should be a row of lights along the wall to ceiling join along the length of the booth, angled at 45 degrees. How many lights you need depends on the quality/output of the lights you choose, but you should aim to have at least 700 lux at about 1 metre height in the centre of the booth. With the old fluorescents this meant banks of 3 or 4 tubes. Watch that many LEDs actually produce less light than fluorescents, so check specifications carefully. If possible also run a row of lights horizontally down each long wall, at about 1 metre height. This helps enormously when painting the side of a car.

Also be very careful about the colour of the LEDs. Colours in the range of 6000-6500K will change the apparent colour of the paint. Better to go for something around 5000-5500K which will render better. There are specific LEDs that are made to render colour accurately - usually a bit more expensive but really worth the extra cost.

That is incorrect on lighting buddy. aim for 90CRI and above. do not go by the Kelvin scale

i have T-5's in my shop and booth 20, 6' ( 2, 3' end to end) and real happy with them OTHER than the cost to operate, and my electric rate just went up 25% ouch! i'm seriously considering LED's this summer and have been doing a lot of thinking i have LED can lights in the kitchen of my house 9' to 10' ceilings. its a large kitchen and we have 9 cans with LED bulbs. they light up the area perfect no shadows and nice color. i'm thinking about doing the ceilings in the shop and booth. in the booth run LED tubes on the wall or put cans in the wall. i'm 2x6 construction so they should fit. there cheep, i just bought a box of13 new cans at a garage sale for 10 bucks.
Jay D.

Thanks for all the replies , good information.
Concerning a fan , what diameter 16, 20 , 24 inch . Planning on building 14x26 9ft walls
Maybe put doors on end with filters . Any particular brand you recommend? Do you guys use a variable speed fan ??
Anyone have pictures of their exhaust fan area ?? Necessary to build a filter area enclosing the fan ?? 110 V or 220 V ??