Liquid Controls V-15, V-30, VS-3, and VS-4 Valves - Manual (Page 4)

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V-15 & V-30 Valves
V-15 valves are designed for use on M-15 and M-25
positive displacement flowmeters; V-30 valves are for use
on M-30, M-40, and M-60 positive displacement
flowmeters.
V-15 & V-30 valve operation is smooth and easy
regardless of the line pressure since the vector forces
are directed at right angles to the valve opening
mechanism and are never in opposition to it.
Depending on the preset, the valve may be operated as
either a two-stage valve with dwell period shut-off or as
a single-stage valve with abrupt shut-off. Single stage
valves are recommended when the application flow rates
are low.
How V-15 & V-30 Valves Work
Inside the valve housing, a cylindrical bore connects the
valve inlet and outlet. Contained within the bore is a
piston assembly. Measured liquid exiting the meter outlet
is blocked from entering the valve inlet by the piston and
seal.
As the meter operator shifts the handle to the open
position, a mechanical linkage connecting the valve to
the preset counter trip ring causes a latch to engage and
hold the valve open allowing liquid to flow.
In the open position, the valve handle assembly
compresses the piston spring and pulls the piston shaft
and the piston away from the valve outlet. As the piston
is pulled away, it disconnects from the inlet seal, allowing
liquid to flow.
In most metering applications, closing the valve is a two-
stage process. At a predetermined dwell period, the
preset counter, while counting down to “0”, releases a
latch mechanism, allowing the valve to close to
approximately 10% of full flow. This initial closing causes
the piston inside the valve to slide toward the outlet,
restricting product flow.
As liquid is blocked by the piston, some product passes
through the valve. The dwell period prevents hydraulic
shock while permitting the preset counter to register the
remaining flow.
As the preset counter reaches “0”, the preset counter
trip ring disengages from the dwell position to the fully
closed position. This action releases the valve handle
and relaxes the piston spring, permitting the piston to
contact the outlet ring seal and complete its closure,
stopping product flow.
General
Figure 1: V-15 & V-30 Valves
Figure 2: Valve Operation