Tag: process control
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How to Effectively Design Control Systems for Distillation Units
A distillation unit is an industrial apparatus used to separate impurities and products of a component based on their boiling point. The distillation process is managed by a control system to ensure optimal operation of the unit.The aim of the control system for a distillation unit is to manage the operations of the distillation process.…
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How to Size a 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 coefficient/valve capacity P1 = Upstream fluid pressure P2 = Downstream fluid pressure ρ = Mass density of fluid Q…
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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 as expressed by an optimization index. The scope of the control tasks varies widely. The…
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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 signal which is either ON or OFF. A limit switch is a mechanical switch in…
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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 signal standards employed in industrial instrumentation are unique. Processes are referred to or measured as 0%…
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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 portable measurements. This device has analogue to digital (A/D) conversion capabilities as well as digital…
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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. The X-Y table may move the table under a stationary tool such as a glue dispenser or may move…
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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. A sensor in this case is a device used to measure the physical parameters such as liquid flow rates, temperature, pressure, speed, and so on. The 4-20…
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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 switch which is different from a transistor that can vary the amount of current in its emitter-collector…
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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 process vessels, pipes and machinery but with instruments superimposed on the diagram showing what gets…