The cost of many modern coatings is in the area of
$100 per gallon or more. If one can recover the coating from the
fluid hose before flushing the hose with solvent, the amount of
money saved can be considerable over a period of time. A 25 foot
length of 5/16” fluid hose contains approximately 12.7 fluid ounces.
Flushing the hose 10 times would waste (or save) about 1 gallon of
Safety warning: DO NOT use the following method to
flush out high pressure equipment. This method is designed to back
flush operations using pressure pots.
Typical recommendations for back flushing a
pressure pot are to hold a rag tightly over the air cap with the
fluid pressure off and the air pressure on. (See illustration 1)
Note that the tank pressure has been relieved and
the tank is open to atmosphere either by opening the tank vent or
leaving the tank lid ajar.
Holding a rag against the air cap with air cap in
“operating” position results in no fluid being back flushed (see
illustration 2). The rag not only blocks the center annular hole of
the air cap, it blocks the fluid tip opening preventing the air from
entering the fluid tip.
Loosen the air cap retaining ring approximately
two turns before applying the air pressure. (See illustration 3).
This position raises the air cap above the fluid tip allowing the
air to flow into the fluid tip, pushing the coating back to the
Back flushing your fluid lines results in lower
coating costs, lower solvent costs and lower disposal costs.