Tag: instrumentation and control
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CAMAC (IEEE-583) Modular Instrumentation Standard
The IEEE-583, IEEE-595, and IEEE 596 CAMAC (Computer Aided Measurement and Control) standards define a hardware and data transmission system which is used to house, support and communicate with various compatible instrumentation modules. A typical CAMAC crate shown in Figure 1.0 below is a physical package which has 25 slots or powered stations for compatible,…
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Testing, Pre-commissioning & Plant Commissioning Requirements
Introduction A new installation must be fully tested to ensure that the equipment is in full working order prior to its being started. This testing is typically divided into three phases: Pre-Installation Testing This is the testing of each instrument for correct calibration and operation prior to its being installed in the field. Such testing…
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What is the Function of a Steam Desuperheater?
Whereas superheated steam offers an excellent source of energy for mechanical power generation, in most cases, steam at greatly reduced temperatures, near saturation, proves a more desirable commodity especially for most heat-transfer applications. Precise temperature control is required to enhance heating efficiency; eliminate unintentional superheat in throttling processes; or to protect the downstream product or…
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Control Valve Selection Guide
Valves are manual or automatic fluid controlling elements in a piping system; in other words, valves isolate, switch, and control fluid flow in piping systems. They are constructed to withstand specific range of temperature, pressure, corrosion, and mechanical stress. Valves can be operated manually using levers or gear operators or remotely using electric, pneumatic, electro-pneumatic…
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Volume Booster: Function, Operation & Application
Function of a Volume Booster A volume booster is a device that amplifies or boosts the volume of air supplied to the actuator, that is, it takes an input signal and produces an output of a large volume flow of air to the actuator; to be precise, a volume booster is a pneumatic device made…
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Instrument Grounding: General Guidelines
Specific attention must be paid to instrument grounding, especially where field instruments are connected to a computer or microprocessor based control system. Where cable screens are used, ground continuity of screens must be maintained throughout the installation with the grounding at one point only such as that in the control room. At the field end…
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Valve Positioners: Function & Types
Basic Features of a Positioner Pneumatically operated valves depend on a positioner to take an input signal from the process controller and convert it to valve travel. In other words, a positioner is a motion control device made to actively compare the stem position against the control signal, adjusting the pressure to the actuator diaphragm…
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Directional Control Valves: Function & Principle of Operation
Directional control valves are used to regulate the flow rate of hydraulic fluid; they are also utilized in pneumatic systems for flow control. Directional control valve works by regulating the movement of the piston in the cylinder. It admits pressurized fluid to either end of the cylinder while providing a return path for fluid being…
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Instrument Manifolds: Function & Types
An instrument manifold also referred to as a valve manifold includes manual valves to isolate and equalize pressure from the process to the transmitter (in this case the DP transmitter) or to isolate a gauge or absolute pressure transmitter for maintenance and calibration purposes. Typically we have the following types of valve instrument manifolds:…
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Pneumatic System Components: Types & Functions
A pneumatic system utilizes air pressure to create mechanical motion. A basic pneumatic system consists of an intake filter that traps dirt before it enters the system, an air compressor that provides a source of compressed air, a dryer that removes the moisture in the air, a pressure tank that is a reservoir of compressed…