Cooling Paint Booths

why does it get hot? You have an integrated drying area with gas heat or lamps?

I havent painted timber but I did run an auto paint line processing Aluminium alloy wheels at a rate of one per 10 seconds.

We found that our heat problems were due to ambient air temp or the product temp, it would be nice to condition the air supply to the painting area but for many small operators this is to costly.

In our case we wanted a quality product so rather than controlling the air temp we controlled the paint flash off by having fast and slow thinners depending on the ambient temperature and also paid close attention to paint viscosity, any paint manufacture worth his salt will be able to assist here.

Craig

Thanks for the interest Craig. As I replied to Aurizon, our booths are located inside our 2500m2 workshop, which isn't insulated. We draw air from 3m above the roof. We manufacture in a city often referred to as the driest city, in the driest state, in the driest continent on earth. Although dry does not relate to heat, we often have weeks of summer temps in the 35 - 40 degree celcius range, with our work shop temp considerably higher.

We are working with our paint supplier/manufacturer in regards to thinners, your point about viscosity may be worth a closer look. Any more suggestions or advise would be appreciated.

Cheers

Thanks for the reply Aurizon. Our booths are located inside our 2500m2 workshop, which isn't insulated. We draw air from 3m above the roof. We manufacture in a city often referred to as the driest city, in the driest state, in the driest continent on earth. Although dry does not relate to heat, we often have weeks of summer temps in the 35 - 40 degree celcius range, with our work shop temp considerably higher. Our initial enquiries into cooling systems have been outside our price range, hence we are looking at every option available. Do you have any suggestions or can you offer us any direction for advise ?

Since your in Adelaide in South Australia have you ever thought of evaporative cooling. Whenever Adelaide gets high temperatures the humidity is usually around 10% or so and raising it to say 55% would cool it considerably. All you would need to implement it would be to install evaporator pads at the inlet for the spray booth. If you set up some sort of control system the make sure the humidity never went over 55% the effect on the spraying and drying process would be negligible.

What problems are caused by the heat that make it so important?

Is the problem product related or operator comfort?

What is the paint "system" that you are using? (Solvent type, coverage thickness)

Also located in Australia, we run "airless" spray equipment 24 hrs a day, 5 days a week. I would not want to introduce humidity into the process here because of potential solvent bloom at those higher temperatures. Humidity at those elevated temperatures may also cause operator comfort challenges. We see similar environment swings to Adelaide plus the wonderful challenge of some weeks above 85% humidity above 30 Degrees C in late spring.

Local auto re-spray man has "space suits" for his operators in the hot times of the year.

Hi Just an Engineer,

If we were talking about anywhere but Adelaide or Perth, then I would definitely agree with you 100%.

However, Adelaide and the surrounding area and a similar area around Perth, have a climate that is completely different and actually the total reverse of the rest of the continent.

The large bulk of Australia is either Tropical or semitropical and receives the lion's share of its precipitation during the warmer months. As a result you tend to get high temperature with high humidity and that would make any sort of evaporative cooling not only useless but prone to the problems you mentioned.

On the other hand Adelaide has what is referred to as a Mediterranean climate and receives most of its rainfall in the cooler months between April and September with very little if any precipitation during the warmer months. As a result you often get temperatures above 35°C (95°F) and on at least 1 day a year above 40°C (104°F) with a relative humidity below 10%.

Conditions like this pose a number of problems like dehydration, drying of the throat and loss of voice and possibly the most dangerous of all static electric build up. As a result you often need to add some sort of humidifier to any air conditioning system to bring the humidity up to at least 40. This in itself will cause a considerable amount of cooling as the latent heat of vaporization will be taken from the air and result in a considerable temperature drop.

So, as you can see we are not talking about introducing moisture that would raise the humidity to unrealistic levels but rather bringing it up to the level that is common in the rest of the continent.

I'm not familiar with the spray painting systems used on aircraft but I would hazard a guess that they wouldn't recommend using it if the humidity was below 10% and possibly much higher.

The other point worth realizing is that you may not need to do much to achieve a considerable cooling effect. As the spray booth is already at an atmospheric pressure below its surrounding area all you need to do is install an evaporator so the air that enters the spray booth passes over it. If you then use a humidistat to control the water going to the evaporator and limit the humidity to 55% you end up with a system that will not cause you problems with high humidity and dramatically reduce the temperature on nearly all the high temperature days.

Sorry for asking more questions before you answer the previous.

What is the exhaust volume for your spray booth? (How much air is going up the stack to draw away your overspray?)

Is your booth fitted with a water curtain or filters to catch the overspray.

I just had a look at the original poster tp's login record and he/she hasn't logged on to CR4 since 13^th April 2007, so I doubt you will get a response to your enquiries.

Nevertheless, I appreciate your response and have learnt something so thanks from me.

have you considered controlling the paint temperature to offset for the temperature issues? Point of application tempcontrol could put you in control of the viscosity and paint fininsh.