A process control arrangement that separates the in-plant measuring points (for example, pressure, temperature, and flow rate) and control points (for example, a valve actuator) from the recorder or indicator at the central control panel.



Related Terms

MULTI-PORT GOVERNOR VALVE

In large turbines, a valve controls steam flow to groups of nozzles. The number of open valves controls the number of nozzles in use according to the load. A bar-lift or cam arrangement operated by the governor opens and closes these valves in sequence. Such a device is a multi-port valve. Using nozzles at full steam pressure is more efficient than throttling the steam.

DIRECTIONAL CONTROL SERVO VALVE

A directional control valve which modulates flow or pressure as a function of its input signal.

FLOW CONTROL VALVE

A valve which purpose is to control flow rate in hydraulic system. Used to regulate how slow or how fast actuators operate f.e. hydraulic cylinder.

ZONE VALVE

A valve that regulates the flow of hot water or steam in a control zone or heating unit of a building.

THREE-WAY VALVE

Multi-orifice (opening) flow control valve with three fluid flow openings.

AUTOMATIC-CONTROL SERVO VALVE

A mechanically or electrically actuated servo valve controlling the direction and volume of fluid flow in a hydraulic automatic control system.

ACTUATOR

  1. A mechanism to activate process control equipment by use of pneumatic, hydraulic, or electronic signals; for example, a valve actuator for opening or closing a valve to control the rate of fluid flow. 2. An auxiliary external electrode used to apply a known electrostatic force to the diaphragm of a microphone for calibration purposes. Also known as electrostatic actuator. 3. A device that produces mechanical force by means of pressurized fluid.

FOOT VALVE

A one-way valve placed at the entrance of a suction line that is opened by the flow of water. The purpose of the valve is to prevent reverse flow.

ASSEMBLY LINE

A mass-production arrangement whereby the work in process is progressively transferred from one operation to the next until the product is assembled.

FEEDFORWARD CONTROL

Process control in which changes are detected at the process input and an anticipating correction signal is applied before process output is affected.

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