Liquid is removed from a remote location, with control of the system responsive to the supply of the liquid to be removed. Control is accomplished without the need for electrical devices at the remote location by means of a valve in the remote location in the conduit circulating a powering fluid to a pump at the remote location, and the sensing of the accompanying changes in flow or pressure in the powering fluid conduit or output conduit.

A pneumatic device for detecting continuously the hydrometric level of a water column, said device comprising a tubular probe dipped into the liquid column by a height greater than the distance between the two maximum and minimum levels set forth previously, a pair of pneumatic detectors of the minimum and the maximum level which are operatively associated to said probe and are put in action by changes in the air pressure occurring inside the probe itself as a function of changes in the column level, a gauge or indicator associated to the maximum level detector for signaling continuously the position of the water level, and means for starting or for stopping a motor-driven pump in correspondance to said maximum and minimum values.

A method for control of the drive means for a reciprocating piston pump delivering liquid to a spring loaded piston liquid accumulator providing high volume compliance whereby the accumulator liquid volume is controlled within narrow limits by continuous control of power to the pump drive motor. The accumulator achieves high volume compliance by arranging the kinematics of a main spring loading the accumulator piston to have a negative spring rate equal to the sum of all other positive spring rates produced by a second spring used to adjust the accumulator pressure, by the diaphragm (piston), and by a flexure support for a sensor lever. This sensor lever moves with the accumulator diaphragm to actuate an optical sensor producing an electric signal indicative of small changes in liquid volume in the accumulator. This signal in turn continuously modulates the power to the motor driving the pump so as to maintain the accumulator liquid volume close to a datum value during a large portion of the pump delivery cycle. This close control of liquid volume in a high compliance accumulator provides substantially constant pulse free pressure liquid delivery from a pulsatile pump. The second spring may be adjusted to modify this constant pressure without disturbing the balance between positive and negative spring rates. Adjustment may be manual or automatic in response to liquid temperature whereby liquid pressure is automatically increased with lower liquid temperatures to compensate for increased liquid viscosity to maintain liquid flow substantially constant through an apparatus such as flow cytometry used for particle analysis or particle sorting.

A control arrangement for a gas-fired system. Three diaphragm-operated valves are in series providing a stage operation. The valves are pilot controlled. A booster pump is provided for cooperation with the pilot valves to boost the line pressure to the first of the valves, the boosted pressure being sufficient to operate the diaphragm valves, and the boosted pressure being controlled by the pilot valves. The booster pump operates only when needed. Diaphragm-operated pilot valves means are provided which operate two separate pilot valves which control the pressure on the opposite sides of the diaphragm of the diaphragm valves. The system provides stage operation, the stages including a first stage which is closing of a vent valve connected between diaphragm control valves, opening of a first diaphragm valve, and a third stage which is a controlled slow opening of the second diaphragm control valve. The first diaphragm valve is both a control valve and a pressure regulator.

A method for control of the drive means for a reciprocating piston pump delivering liquid to a spring loaded piston liquid accumulator providing high volume compliance whereby the accumulator liquid volume is controlled within narrow limits by continuous control of power to the pump drive motor. The accumulator achieves high volume compliance by arranging the kinematics of a main spring loading the accumulator piston to have a negative spring rate equal to the sum of all other positive spring rates produced by a second spring used to adjust the accumulator pressure, by the diaphragm (piston), and by a flexure support for a sensor lever. This sensor lever moves with the accumulator diaphragm to actuate an optical sensor producing an electric signal indicative of small changes in liquid volume in the accumulator. This signal in turn continuously modulates the power to the motor driving the pump so as to maintain the accumulator liquid volume close to a datum value during a large portion of the pump delivery cycle. This close control of liquid volume in a high compliance accumulator provides substantially constant pulse free pressure liquid delivery from a pulsatile pump. The second spring may be adjusted to modify this constant pressure without disturbing the balance between positive and negative spring rates. Adjustment may be manual or automatic in response to liquid temperature whereby liquid pressure is automatically increased with lower liquid temperatures to compensate for increased liquid viscosity to maintain liquid flow substantially constant through an apparatus such as flow cytometry used for particle analysis or particle sorting.