Abstract: An apparatus having latching effect for limiting pressure in liquid feeding systems has a valve means inserted in the feeding path of a pump supplied liquid. The valve means includes a shunt valve opened upon excessive output pressure; the shunt output of the shunt valve is connected to a feed-back tube. There is further provided a back-stroke valve in the main feeding path of the liquid. A first pressure switch has the output pressure applied thereto while to a second pressure switch the input pressure at the shunt valve is applied. The two pressure switches are inserted into the switch-on circuit of the pump in such a manner that the pump is switched-on in the presence of a low output pressure and switched-off in the presence of an excessive output pressure.

Abstract: The pump comprises a pump stator (5), an electric motor stator (4), and a rotor (6) that constitutes the rotor both of the pump and of the electric motor. The pump stator comprises a tubular non-magnetic lining to the electric motor stator, and the rotor is mounted excentrically inside said tubular lining and is equipped with radially movable vanes (63) that co-operate with said lining to provide pumping action when the rotor rotates. The arrangement is particularly applicable to oil-sealed vacuum pumps, and has the advantage of being more compact than units of similar performance, but equipped with a pump and a motor that are separate and interconnected by a mechanical coupling, as is conventional practice.

Abstract: In an inverted siphon (4) in a sewer (1, 1a) where the approaching flow of sewage is insufficient for producing self-rinsing, a fluid reservoir (5) is arranged upstream of the inverted siphon which has sufficient volume for effecting rinsing, and the fluid content of the reservoir intermittently by means of driving members (6, 8, 9) is emptied through the inverted siphon at a velocity which corresponds to and at least during a certain time exceeds the required rinsing velocity.

Abstract: An airless hydraulic diaphragm paint pump having a pumping chamber subdivided by a diaphragm into pumping fluid and pump fluid subchambers with an inlet from a pump fluids storage and an outlet to a pumped fluid utilizer such as a paint spray gun. A bypass port is provided for returning pumped fluid to the source at a low pressure. A pressure release valve in communication with both the outlet and the bypass port is effective to allow bypassing the pumped fluid directly back to the source and to bleed the line between the pumped fluid utilizer and the pump. The valve is actuated by a solenoid actuator and is opened when the pump drive is terminated or manually or in the event of an excessive high pressure.

Abstract: A valve device is disclosed for unloading pressure from a compressor of the type utilized in a medical respirator. The device is formed with a cylindrical chamber containing a compressible elastomeric member. Inlet and relief ports of the valve open into the chamber, and the inlet port is connected with the outlet of the gas compressor. Bistable actuator means is provided for moving a plunger within the chamber which in turn causes the cylindrical member to assume either a compressed or uncompressed state. In its uncompressed state a radial clearance between the outer wall of the elastomeric member and the chamber provides a flow path between the inlet and relief ports to bleed pressure from the compressor. In its compressed state the elastomeric member expands to occlude the flowpath and prevent pressure bleed-off from the compressor.

Abstract: The operation of a 4-way, open-center, three position hydraulic valve is coordinated with the operation of the pump for the hydraulic system in which the valve is controlling flow. As the valve is moving from its open-center position to either one of its other two operative positions, a switch maintains the power circuit for the pump open and closes that circuit to activate the pump after the valve has assumed one of the other two positions.