8
Theory of Operation;
The TUTHILL meters LPG metering system combines an
oval gear positive displacement meter, differential valve,
strainer and vapor eliminator in one assembly. The differen-
tial valve incorporates a diaphragm type construction with
the piston moving away from its seat when at least 15 PSI
pressure (above product vapor pressure) is maintained at
the meter outlet. The differential valve assures measure-
ment accuracy by requiring pump operation for delivery, by
requiring adequate back pressure to prevent product vapori-
zation during measurement and by requiring blockage of
flow when the vapor eliminator release valve is open. The
strainer prevents foreign particulate from entering and dam-
aging the meter. The meters close tolerance machine con-
struction and no metal to metal contact provides accurate
liquid measurement.
Installation, Flow Meter:
Install the meter assembly to a secure base using the bolt
holes on the “feet” of the meter assembly base. Make inlet
and outlet connections at the flanged surfaces on the meter-
and differential valve, respectively.
Leave a minimum of 12
inches between he strainer flange and any obstacle for
servicing the strainer.
I
nstallation, Vent Line:
The vent line from the meter’s vapor vent to the vapor space
on the supply tank should be a minimum of 1/2” inside diam-
eter tube or pipe. A shutoff valve must be installed in the
vapor vent line to allow removal of the strainer or service on
the meter. The vapor release vent line must be returned to
the vapor space of the supply tank and normally should not
be made common with the other vapor return lines or pump
by-pass lines.
When properly installed, this line must permit free flow in
either direction. If the vent line is closed the meter will not
function, as the differential valve will not open. These in-
structions must be followed to maintain proper function of
the differential valve.
Support:
Prevent pipe strain or stress from occurring when making
connections to meter or accessories and during repairs.
Pipe strain and stress occurs when the pipes are not sup-
ported or are not aligned correctly to the meter. The weight
of the pipes must always be supported independent of the
meter. This meter and accessories can easily be removed
without affecting the pipes or the pipe alignment. Never
leave any of the pipes hinging.
Storage:
If the meter is used for seasonal work, at the end of each
season the meter should be removed from the system and
thoroughly flushed with a compatible liquid. This includes
removing the drain on the front and rear covers. Then flush
the product from the front and rear covers. If flushing with
water is preferred, extra care should be taken to drain the
meter completely and to dry all internal parts. Immediate
refilling with a compatible liquid (or oil misting) is essential to
prevent corrosion as well as ice damage to parts from mois-
ture that was overlooked after flushing and drying.
Installation & Operation continued
Typical Installation Diagram
mdi - Manufacturers Distributor Inc. | Phone: (813) 241 - 4900 | Fax: (813) 571 - 0422 | www.FillRitePumpSales.com | [email protected]
