• Start by upgrading the fan motor.  Replace it with one meeting the newer, premium energy efficient electric motor standards.  These motors are constructed using heavier wire, better grades of steel, thinner and longer laminations and better bearings.  The efficiency increase is particularly significant in the lower horsepower range.  For example, a typical filter booth is equipped with a 5 hp, 3-phase motor.  The standard efficiency motor supplied with the booth has a power conversion efficiency of 84%; while its premium efficiency cousin will have a power conversion efficiency of 89.6%.  According to U.S. Department of Energy (DOE) the cost of the electrical power consumed by an industrial motor over its useful life is 30 times its initial purchase price.  The cost premium for an energy efficient motor is frequently recovered in less than a year

• Resist the temptation to oversize the fan motor.  Over-sizing the motor adds cost in two ways.  The initial purchase cost will be higher and the actual operating energy efficiency will be lower, needlessly inflating its power consumption.  Consult NEMA (the National Association of Electrical Manufacturers) or the motor manufacturer's guidelines when sizing a replacement motor for your booth.  Usual practice is to operate motors in their most efficient range - 75% to 100% of their full load rating.

• Replace inefficient, power consuming, mechanical control devices, such as variable speed pulleys, dampers and bypass vents with a variable frequency drive (VFD) designed to drive your new energy efficiency motor.  The DOE estimates industrial motor energy consumption could be reduced by up to 18% if companies replaced their motors with high efficiency ones and powered them with energy efficient electronic variable frequency drives.

• Consider upgrading the spray booth to include energy efficient, closed-loop constant airflow control technology.  This new control package includes both an energy efficient motor and a variable frequency drive.  The closed-loop system automatically maintains the preset exhaust airflow as your booth's arresting filters load with overspray by monitoring the actual exhaust airflow and adjusting the motor rotational speed to maintain it at the preset level. The system consumes only as much power as is needed to maintain the preset exhaust airflow at any given moment in time.  An added benefit of upgrading the booth airflow control system is gaining a stable environment for the spray finishing operation the booth houses. Practitioners of six sigma and other popular continuous improvement disciplines find constant booth airflow enables them to fine tune the entire spray application operation, further reducing the line's operating cost.

The following are the only solutions recommended for use by the manufacturer of the polycarbonate material:
Compatible Cleaning Agents

• Windex with Ammonia D
• Mr. Clean
• Top Job
• Fantastik
• Joy
• Palmolive
• Formula 409

Organic Solvents

• Naphtha (VM&P Grade)*
• Kerosene* (DO NOT USE GASOLINE)
  *  Following immediately with a thorough soap and water cleaning.

Alcohols

• Methanol
• Isopropyl

Scratch Repair

If scratching should occure, minor abrasions can be removed or minimized by using a mild automobile polish.  Examples of such polishes include (1) Johnson Paste Wax, (2) Mirror Glaze Plastic Polish (M.G.M10-Mirror Bright Polish co., Pasadena, CA), (3) Plexus (B.T.I. Chemical, Aguora, CA), and Novus Plastic Polish #1 and #2 (Novus Inc., Minneapolis, MN).

NOTE:  A test should be made on a sample area with the selected product before all over use

DO NOT

• Use abrasive or highly akaline products
• Scrape walls with squeeges, razor blades or other sharp instruments
• Use Bensene gasoline, acetone or carbon tetrachloride
• Clean while booth temperature is elevated or when a high percentage of humidity exists

Preventative maintenance on a spray booth will help reduce the likelihood of fires and explosions.

• Regular maintenance of the booth system and maintaining its systems in good order contribute to the fire prevention effort by removing flammable accumulations and dust, as well as make a clean finish possible.
• Use of the booth requires a regular schedule of filter replacement.  Codes require that filters be inspected after each period of use and that clogged filters be discarded and replaced immediately, another practice that contributes to fire prevention as well as a clean finish.

Daily

• Clean/wipe down air hoses

Weekly

• Vacuum interior of spray booth
• Wipe interior of spray booth walls

Quarterly

• Clean light fixture glass
• Vacuum pit and tunnel
• Clean and remove overspray from floor
• Check motor belts 
• Pressure wash floor grates
• Inspect door seals (replace when required)
• Check and tighten all electrical connections
• Service airflow switches

Semi-Annually

• Lubricate door hinges
• Pressure wash spray booths
• Lubricate blower shaft bearings
• Calibrate booth pressure balancing gauge
• Fire suppression system

Annually

• Clean light tubes
• Check light fixture glass seals
• Clean inside of all light fixtures and glass
• Clean exhaust stack, dampers and stack head
• Clean main exhaust blower/fan
• Burner system tune-up (start-up procedure)
• Clean upper plenum
• Lubricate motors

As Required

• Door seal/gasket replacement
• Door hinge brass bushing replacement
• Replace light tubes and ballasts

The proper air flowing into a spray booth meets the following conditions:

The air volume in the plant (cubic feet) should be 20 times the air exhausted in one minute by the spray booth. Put another way, you want no more than three plant air changes in one hour. The following gives an example of using plant air. To calculate booth exhaust air multiply booth face square feet by velocity required.

Multiplying the air exhausted by 20 yields a plant volume requirement of 768,000 cubit feed, or a building size of 200' x 256' with 15' ceilings.

Any measuring device used to measure air velocity in a paint booth requires energy from the air stream to operate.  Some instruments are more efficient than others.  We have used velometers and anemometers in the past (with spotty results) and have come to distrust their readings.  In addition, at low flow rates the technician is a large enough object to disturb or interfere with the readings. 

Paint booth velocities are very low (50-100 fpm).  When you look at the formula for converting velocity pressure to velocity, it is apparent that distinguishing low-velocity airflow rates is a very inaccurate process.

The average gas (air) temperature and the average square root of the velocity pressure are used in the equation to calculate the average velocity.

Note:  In the above equation, the velocity pressure has units of inches W.C. and the average pressure has units of inches Hg.  At standard air conditions this simplifies to v=4001 x VPO.5 (Table I provides some useful 00 results).

It is easy to see that there is little or no energy in the air at 50 or 100 fpm to give a good reading.  The instruments are good, and they do what they can to relate their results as accurately as possible, but there is little to work with.  The energy available at 1,000 fpm is 200 times that available at 100 fpm.

At the higher levels of velocity, it is possible to get excellent readings and have minimum impact on the measured airflow velocity.  Therefore, it is possible to say that taking readings with a handheld device in the booth is troublesome and fraught with inaccuracies, while measuring air speed at much higher velocities (i.e. the discharge duct) is very simple and very accurate.

We find that drilling a hold in the side of the duct (in a nice straight section of duct) is extremely accurate.  Converting that velocity to booth average air velocity is a matter of dividing the result by the booth cross-sectional area.  The average air velocity will suffice to show compliance with codes and regulations.

The use of a velometer can have excellent results at detecting eddies and other problem areas in the booth.  When the needle bounces around and becomes unstable, this indicates that air is entering both ends of the velometer.