Retrotec USACE - Manual (Page 237)

Appendix D D107
D.7 Process Systems
D.7.1 Painting
D.7.1.1 Operating Paint Booth Ventilation System When Not
Painting (Waste)
Figure D167. Paint booth with exhaust system
continuing to operate when fi nished painting.
Paint booths require a signifi cant rate of ventilation air to dilute paint fumes and
the solvents contained in the paint. This is to reduce the concentration of the
solvent in the air to below the lower explosive limit and also to help protect the
workers from breathing unhealthy concentrations. A ventilation rate of 30.5 m/
min (100 fpm) of booth opening is a typical amount exhausted. The operation of
the paint booth ventilation requires fan motor energy to be consumed by both the
exhaust and supply air systems. The supply system must also use heating energy
to temper the air in winter. The paint booth ventilation system needs to operate
when painting is taking place and for a time of approximately 20 minutes after
painting is completed to remove solvent vapors as the fl ash-off from the recently
painted items occurs. After this time period, the fl ow of the ventilation system can
be reduced or turned off. Failing to do so is a waste of energy (Figure D167).
D.7.1.2 Painting When Item to Be Painted Is at Improper
Temperature (Ineffi ciency)
For proper painting it must occur within a specifi ed temperature range. Typi-
cally it is at room temperature, or 21–27 °C (70–80 °F). At times the item to
be painted has been outside for a period of time and in winter would have a
temperature much lower than the required temperature. These items must
then be warmed to be ready for painting (Figure D168). This is normally ac-
complished by placing these items in the paint booth and waiting until they are