Abstract: A valve for controlling fluid flow in a fluid system is disclosed. The valve includes a housing, a servo spool, and a piston. The servo spool defines a spiral groove and a spiral land. The piston defines an orifice configured to provide flow communication to a supply of pressurized fluid and an orifice configured to provide flow communication to a portion of the fluid system exterior to the valve. The valve further includes a main spool operably coupled to the piston. The main spool is configured to control flow of fluid in the fluid system. The spiral groove and spiral land are configured such that angular displacement of the servo spool results in a force imbalance on the piston, thereby moving the piston and the main spool in one of a first direction and a second direction.

Abstract: A check valve includes a casing member, a tear-drop shaped ball member installed in the casing member, a latching member which is formed at an inner wall of the casing member and an airtight valve which is formed at an inner wall of the casing member. When forward flux occurs, the ball member is fixed at the latching members absolutely to circulate the forward flux stably. When backward flux occurs, the ball member is latched at the airtight member to close the casing member and thus, to suppress the backward flux.

Abstract: This is a method and means for maintaining a constant supply of a fluid with specific characteristics within a fluid supply conduit from a supply source of the fluid with specific characteristics at a point of service of the fluid with specific characteristics in which a first open end of a recirculation conduit is located within the fluid with specific characteristics supply conduit adjacent the point of service. A second end of the recirculation conduit is connected to pump means in such manner that a portion of the fluid with specific characteristics within the fluid with specific characteristics supply conduit adjacent the point of service is constantly circulated back. In an alternate embodiment a similar recirculation conduit is utilized in a manner to prevent freezing of conduits in a total fluid supply line which includes portions in relatively warm areas and in areas subject to freezing.

Abstract: A safety check unit for use in a liquid distribution system for preventing damage to a pump and associated components of the system in event of loss in pumping pressure. The unit provides a check component to prevent back-flow of the liquid when the pump is shut down, and provides protection against a possible vacuum condition in the system by introducing air to the system; protects against damage by a surging back-flow of liquid by opening a relief port of the unit; and protects against air in the system by use of an air relief mechanism of the unit.

Abstract: A casing accommodates therein a movable valve adapted to be moved away from a valve seat by a hydraulic oil flowing through an oil-hydraulic circuit from a hydraulic cylinder to an oil-hydraulic pump. In an event of oscillatory hydraulic pressures in the hydraulic cylinder, the hydraulic oil is returned through the oil-hydraulic circuit from the hydraulic cylinder to the oil-hydraulic pump via a second port, a communication path, a minor gap between the movable valve and the valve seat, and a first port. In this process, the communication path allows for a smooth flow of the hydraulic oil from the second port into the movable valve.

Abstract: A plumbing system which, when ambient outdoor temperatures drop below freezing, circulates water to prevent it from freezing, utilizing a check valve to prevent water from flowing back into the water main and further utilizing a relief valve which can open to the atmosphere and relieve pressure in the system if necessary. The system can have two separate circulation pumps, one for hot water and one for cold water.