While these gadgets – "toys" for
adults, as they’ve been called – are often fun to add (Tim Allen’s
character on the television show "Home Improvement"
is a lover of gadgets, i.e. his turbo lawnmower), many of them
also serve a purpose. In the case of spraybooths, gadgets can
enhance the performance of your old crossdraft or new downdraft
– and they’re a low-cost alternative if you’re not ready to invest
in a brand new booth.
Gadgets Galore
- Are you achieving proper metal temperatures? Changes
in paint technology have made it increasingly critical to ensure
that the proper curing temperatures are achieved. It used to be
that we were to heat a spraybooth to approximately 140 degrees;
today, we’re told it’s necessary that the panel temperature of
the painted vehicle reach 140 degrees for a specified length of
time. The problem? Spraybooths are set up to monitor the air temperature,
not the panel temperature.
Solution? A retrofit kit is available to convert spraybooths
to monitor panel temperature. This is accomplished by modifying
the booth’s temperature controller to respond to the car’s metal
temperature instead of the booth’s air temperature.
For example, if the desired metal temperature is 140 degrees,
the booth temperature will maximize to maybe 175 degrees and remain
there until the desired 140-degree metal temperature is achieved.
Once achieved, the air temperature will drop to approximately
145-150 degrees to maintain the metal temperature of 140 degrees.
The cure timer will then start, and the booth will remain in the
bake cycle until the "user set" bake time has expired.
- Loss of gloss or slow drying of high-solids paints?
Many paint booths are designed to recirculate most of the air
during the bake cycle. This has worked well for many years, but
recently, manufacturers have increased the solids content in their
paints – making it more difficult to cure their products with
a recirculating system.
Air that’s recirculated is partially saturated with solvents before
it tries to dry a car. It’s like wiping up a spill with a wet
sponge instead of a dry sponge – every pass with the dry sponge
absorbs more than every pass with a wet sponge. The same applies
to "fresh" or dry air in curing paints.
Solution? It’s usually possible to add fresh air to a cure cycle
by making adjustments to damper positions and allowing for additional
exhaust of the air during the bake cycle.
- Tired of manually adjusting booth pressure? Many paint
booths have a damper to operate either by hand or by a control-panel
switch that’s used to maintain a desired booth pressure. Still,
many adjust the booth pressure manually.
Solution? An automatic, cabin-pressure-control retrofit
system is available that will:
- Read the booth pressure;
- Adjust the damper until the booth pressure is at the set point;
and - Continue to read the pressure and make adjustments to maintain
the set point. - Is it time to change that filter yet? So many times, spraybooth
filters are changed either too soon or not soon enough.
Solution? The best way to decide when to change a filter
is based on the "pressure drop" across the filter –
this can be accomplished by using a special "reading"
tube called a pitot (pe-to) tube. A patent-pending kit is available
that will not only indicate the proper time to change the filters,
but will also call your filter supplier to tell him to send the
filters!
- Gas odor inside the booth? The life expectancy of heat
exchangers varies depending on the initial integrity of the steel
used, type and frequency of burner maintenance and even how the
heat exchanger was installed. I’ve seen them last less than five
years – and I’ve seen them last longer than 10 years.
If you smell "gas" inside your booth and your booth
has a heat exchanger, suspect that yours is badly cracked and
in need of certified welding and/or replacement.
Solution? Many spraybooths can have the heat exchanger
replaced with a direct-fired burner, which provides a faster temperature
rise and is more cost efficient to operate.
- Monitoring difficulty? It can be complicated to monitor
multiple booths – even more so when you own more than one shop.
Solution? With the advancement of Direct Digital Control
systems, it’s possible to monitor multiple booths at the same
site or different sites. This can be limited to simply monitoring
the condition of filters, or it can include all vital functions
of the booth – such as temperature control, damper positions,
burner control, fan control and even lockouts to prevent unauthorized
use.
"Extra" Efficiency
Why add "extras" to your current spraybooth?
Maybe you can’t justify the expense of a new booth right now,
so you decide to improve on the one you’ve got. Maybe you bought
a new downdraft a few years ago but weren’t aware of all your
options.
Before deciding to "gadgetize," though, think long and
hard as to whether it’s economical to sink more money into your
current booth. Examine the costs and benefits. These "extras"
may be cheaper than the cost of a new booth, but that doesn’t
mean they’re a wise investment for everyone.
