Positive displacement piston flow meter for air flow measurement
AssigneeGilian Instrument Corp.
InventorsHill S. Lalin, William T. Fleming, Jr.
Life of this patent
Estimating the term…
Abstract
A positive displacement piston flow meter for measuring air flow comprising a hollow flowtube, preferably arranged in a vertical orientation, having a movable piston disposed in the flowtube for movement between a starting position, preferably at the bottom end of the piston stroke, and an elevated position at the top end of the piston stroke. The piston is reciprocated by means of a pressure relief control valve assembly which controls the ascent and descent of the piston. The piston is physically connected to the pressure relief control valve assembly by means of a flexible string, which causes the piston to automatically close the valve assembly for automatic operation on reaching the bottom end of the piston stroke and to reverse direction.
Claims8
A positive piston flow meter for use in measuring air flow comprising:
- (a) a hollow flowtube vertically oriented to form a top end and a bottom end, and having a movable piston disposed therein for movement between said top and bottom end, respectively;
- (b) inlet means for connecting one end of said flowtube to an external pump, with said flowtube having ingress and egress to the ambient atmosphere from at least one end thereof;
- (c) means for detecting said piston as it moves past at least two predetermined positions along said flowtube from which air flow through said flowtube can be measured;
- and
- (d) a pressure relief control assembly for controlling the ascent and descent of the piston in said flowtube, said pressure relief control assembly comprising:
- a housing, a chamber within the interior of said housing, and a poppet valve for interconnecting said said flowtube to said chamber, with said poppet valve having a first position for providing a first flow path to said inlet means from said top end of said flowtube to cause said piston to rise, and a second position for providing a second flow path from said chamber to said inlet means to cause said piston to fall;
- and with said poppet valve, including a valve stem extending into said flowtube for engaging said piston when said piston reaches a fixed position adjacent the top end of the flowtube, whereby said poppet valve is automatically switched into said second position to permit said piston to descend by gravity from the top end of said flowtube;
- latching means for holding said poppet valve in a fixed position after said piston and said valve stem have disengaged, and means for resetting the poppet valve into said first position.
Dependencies are inferred from the claim text.