Tag: process control
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How to Size a Control Valve
Pneumatic control valve Control valve sizing refers to the procedure determining the correct size of a valve body. A valve sizing equation for incompressible fluids is given by: Which is the same as: Where Cv is the valve flow … Read more
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Process Control System Design for a Distillation Unit
The aim of a typical control system is to force a given set of process variables to act in some desired and prescribed way by either fulfilling some requirements of the time or frequency domain or achieving the best performances … Read more
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Limit Switches vs. Proximity Sensors
An object can be used to activate a switch directly, producing an ON or OFF signal to indicate the presence of that particular object, alternatively we can use the presence of a nearby object to activate a sensor giving a … Read more
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Standard Process Signals for Industrial Instrumentation
Industrial measurement and control processes employ standard process signals that are used throughout all the industries. For instance, one of the most popular forms of signal transmission in modern industrial instrumentation systems is the 4-20 mA DC standard. The … Read more
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The USB-6009 Data Acquisition Card Features
The USB-6009 is a small external data acquisition and control device manufactured by National Instruments that is normally connected to a computer through a USB port. It is used in applications such as simple data logging, academic lab experiments and … Read more
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How X-Y Tables are used in Position Control Applications
X-Y tables are utilized as components in many systems where reprogrammable position control is desired. The X-Y table is two servo-controlled linear actuators (often servomotors and ball screws) with their linear axes perpendicular to each other. Fig: X-Y table, … Read more
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Basic Facts about 4-20 mA current loop in Process Instrumentation
The 4-20 mA current loop, like the one shown in the diagram below is a typical way of transmitting sensor information in most of industrial process monitoring applications. Figure 1.0: typical components used in a loop powered application. A sensor… Read more
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Optothyristors: Features & Principle of Operation
Silicon Controlled Rectifiers (SCRs), Triacs and other solid-state devices used for switching larger voltages and currents ON and OFF are referred to as thyristors. Thyristors control switching in an ON-OFF way, in the same way to a light … Read more
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PFDs vs. P&IDs
Process Flow Diagrams (PFDs) defines the major elements of the process schematically i.e. the interconnections of process vessels, pipes and flow paths of process fluids. On the other hand, Piping and Instrument Diagrams (P&IDs) shows the layout of all relevant … Read more
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Process Instrumentation Diagnostics & Communication Interfaces
There are various technologies that are available that help plant automation personnel to obtain diagnostic data which inform the type of maintenance to be undertaken. For example, using Distributed Control System (DCS), PC software tools, or handheld communicators, plant … Read more