| Lin’s has found
that maintenance to the Flowmatic valve is one of
the most neglected parts of the tanker, causing unnecessary
down time at the most inopportune moments.  The
Flowmatic valve filter, Rego part #A7884-201,
should be changed at least once a year. For the do-it-yourselfer,
a replacement filter costs less than $50.00 and it
is well worth including this filter replacement with
your other annual maintenance chores. Lin’s
recommends changing the filter with each VK test.
The meter’s strainer should be cleaned at the
same time.
The directions for changing the Flowmatic filter
and cleaning the meter strainer follow. Only
those trained and experienced with the safe handling
of propane, and knowledgeable of the truck’s
piping should attempt this task. Also, make sure that
you perform this operation in a safe location away
from potential hazards.
The first job is to depressurize the piping system
after the main valve. Shut off the prime screw on
the Flowmatic valve, to the left of the indicator,
2-1/2 to 3 turns. Next, shut the ball valve after
the meter, shut the vapor return to the meter, and
shut the bypass ball valve. At the meter, crack a
half turn the fittings securing the lines to the differential
valve and the vapor eliminator.Crack the Flowmatic
filter line with the 3- way valve OPEN. As the propane
vents the cracked lines, monitor the in-line pressure
gauge. If the pressure gauge doesn’t show a
substantial decrease in pressure over time, something
is wrong and end the procedure. The truck should be
brought to a propane repair shop. When the pressure
gauge reads zero AND there is no evidence of gas in
the lines, it is safe to remove the Flowmatic filter.
Unthread and remove the old filter. Apply pipe dope
to the threads of the new filter and place 2.5 wraps
of Teflon tape clockwise on the inlet and outlet.
Refit the 3/8” brass flare fitting to the inlet
side of the filter, then attach the filter to the
piping.
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The next logical step is to clean the meter strainer.
Remove the lines off the vapor eliminator and differential
when there is no further pressure in the lines. You
can then begin to loosen the strainer cover, when
there is no evidence of additional gas in the lines.
Do not rely only on the in-line pressure gauge! Use
your
head. If you remove the strainer cover prematurely,
the cover could blow off or a blast of propane could
cause a serious frostbite burn in a rather sensitive
area. Have you noticed where
the strainer cover lines up on the average man? Enough
said… but please proceed carefully. Next, begin
to loosen each of the strainer cover bolts 1/2 a turn
at a time - in sequence. This means, give a 1/2 turn
to the first bolt, 1/2 turn to the second bolt, and
continue. When the bolts are finger loose, pound the
cover loose with a rubber mallet. When the seal is
broken,
remove the cover. Pull the strainer out. Be careful
to keep the strainer level to avoid contaminants from
falling in. Clean and inspect the strainer. Inspect
also the o-ring. If in good condition, oil the o-ring
with lightweight oil and reinstall. Reassemble by
reversing the procedure. To repressurize the system,
open the
prime screw on the main valve. The in-line pressure
gauge will begin to rise. When 2/3 of the tank pressure
is reached, reopen the bypass, vapor and liquid lines
after the meter. It is important to repressurize
the piping system slowly to avoid seizing
up the meter measuring chamber.
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