How Does a Control Valve Works ? Control valve is a process control instrument is used to control the flow, pressure, level and temperature using pipeline fluid flow controlling. Control Valve operates pneumatically and is positioned by a 4–20 mA control signal. control valve operate from PLC, DCS and simple PID controllers  1. Basic Working Principle A control valve regulates flow, pressure, temperature, or level by changing valve travel according to a controller signal (typically 4–20 mA ). 4 mA = min (usually closed)  to 20 mA = max (usually open)  2. Pneumatic Operation (step-by-step) Controller outputs 4–20 mA . An I/P converter converts current to pneumatic pressure (commonly 3–15 psi or 0.2–1.0 bar ). The pneumatic actuator receives air pressure and moves the valve stem/plug/ball. The valve opening changes the process flow. 3. Key Components Positioner — ensures accurate valve position for the given signal; compensates for frict...

What is a ruptured disc? Basically the rupture disc is a device used to prevent the vessel from breaking due to increased pressure. It consists of a thin metal diaphragm that explodes when the vessel's pressure rises. Rupture discs are usually designed to reduce to 1.5 times the vessel's maximum allowable working pressure. A disc assembly consists of a thin, circular membrane usually made of metal, plastic, or graphite that is firmly clamped into a disc holder. It works on the pressure relief principle. Rupture discs are actuated by inlet static pressure and are designed to function by bursting a pressure-loaded disc. The disc may be made of metal or carbon graphite and placed in a suitable holder..

What are digital instruments?  Basically digital measuring instruments show the measured value in digital form which will be number along with its unit. And it is much easier to read compared to analog devices. One can easily measure and note the measured value by these digital devices as it will indicate the measured value in numerical form. They can give readings to one or more decimal places. There will be no human error in this type of equipment as it will show the value as calculated from the function. Hence the measured value will be more accurate as compared to analog instrument.

What are Analog Instruments? Basically, analog instruments represent the magnitude of a quantity as a moving indicator. We want to measure readings from such instruments because there are certain marks on the scale. and they represent whole number values even though the markings in the instrument may give readings to one or two decimal places. Although we can calculate to two decimal places, it is not accurate or completely correct. We cannot get a completely accurate value in this range every time because some human errors may occur.

What is a measuring device? Basically an instrument used to measure a specific physical quantity is called a measuring instrument. And measuring instruments are used in our daily life to measure various quantities like length, weight, temperature, pressure, current, voltage etc. Instruments represent the value of physical quantities, through which we make certain understandings and process certain activities and decisions. . The main purpose of this measuring instrument is to measure a physical variable in its units, display the variable in its units, and record the value in its units.

What is Flue Gas? Essentially flue gas is the gas emitted from the combustion process in a power plant, flue gases come in many different forms that enter the atmosphere through flue ducts and chimney openings that enable the gases to travel from the source to the local environment.

What is Centrifugal Machine? Basically, a centrifugal machine consists of a cylindrical stainless steel basket. The basket is mounted on a fine circular rod with perforated sides lined with wire cloth and metal sheet with 400 to 600 holes per square inch. And the speed of centrifugal machine is 1500 to 2100 RPM. A centrifuge machine works on the principle of sedimentation. which is influenced by the force of gravity. Materials are separated based on their density. Different methods of separation include isopycnic, ultra-filtration, density gradient, phase separation and pelleting.

How many types of submersible pumps are there and what components are used in submersible pumps? Basically, there are various types of submersible pumps available in the market Deep well pump Bottom suction pump Stainless steel pump Oil filled pump Submersible utility pumps Water cooler pump Mixed and axial flow pumps The components of a submersible pump are as follows: Clamps Check the valve Submersible pump pressure switch torque arrester Tank tees Drain valve Relief valve Impeller safety rope Pump cable Sludge filter Inlet and outlet valves

What is a submersible pump? It is basically a centrifugal type pump. And instead of pulling water like normal cases, a submersible pump pushes water. It consists of a hermetically sealed motor attached to the pump body which helps in pushing the liquid to the surface. The impeller plates used in this pump are of backward curved type, which helps to push the water with great force. Its motor converts rotary motion into kinetic energy, and diffuser blades convert this kinetic energy into pressure energy.

What is Buchholz Relay? Basically Buchholz relay is used to detect internal faults in oil filled transformers. And that oil is used as insulation for the transformer body. This relay works on the principle of gas detection. and is also known as a safety device used in oil-filled transformers. When internal faults occur inside, the current goes up to a very high abnormal range. This high current automatically increases the operating temperature inside. As the oil is filled in, the excess heat generated causes it to evaporate. As it begins to change to gaseous form, it rises to the oil reservoir. A Buchholz relay is placed between the protector and the transformer tank (body). It detects this gas and immediately trips the circuit. This means the transformer is closed for operation, thereby avoiding any untoward incident.

Types of Relays Used in Air Circuit Breaker (ACB) Basically internal protection and tripping applications, relays are used internally in air circuit breakers to make it more efficient in operation. And generally three types of relays are used in air circuit breaker. shunt coil relay Under Voltage (UV) Relay closing relay Shunt Coil Relay Basically this relay can also be called as power relay for air circuit breaker. Shunt coil relay is an automatically controlled relay, which can be operated remotely to open or close a circuit breaker. Just like a PLC operates a relay, this shunt coil relay can also be operated (on or off) by it. The operation of this relay directly opens or closes the circuit breaker. Under Voltage (UV) Relay Basically this relay is used to detect under voltage in the incoming power supply. Overvoltage is a simple natural problem that the circuit breaker will detect and trip the path. When the incoming voltage is low and usually less than 380 V, the load connected in ...

What is the application of bimetallic strips?  Bimetallic thermometers basically use bimetallic strips to measure local temperatures in process industries. And spiral bimetallic strips are used in air conditioning thermostats. And it is used for simple on/off switching applications.

What is a decoder?  Decoder   Basically a decoder is a combinational logic circuit used to convert a piece of coded information into another signal pattern. And the decoder converts 'n' number of inputs into 'm = 2^n' number of unique outputs. Such decoders are generally described as N-line to M-line decoders. A decoder has only one high output for any given code. This is the opposite of an encoder and a special case of a demultiplexer without an input line. And the decoder can be used to perform code conversions or to detect the presence of a particular binary state and thereby activate other circuits based on the input. And simplest decoder is a single logic gate such as an AND or NAND gate with an input inverter, whose outputs are active when the all inputs are high. When combined with an inverter, a NAND or AND gate can produce an output for a unique combination of inputs. So, the decoder used in practical applications is an extension of the simplest decoder and con...

Self Adaptive Control Basically self-adaptive control is one of the major types of the adaptive control. And it is comparable to the feedback compensation because the adaptation of controller parameters is based on the closed-loop performance measurement and the objective is to optimize it using process reference models or estimation techniques. In self-adaptive control, the controller parameters are generated for each process condition and are the  not programmed as in the case of programmed adaptive control. The parameter adjustment loop searches for optimal values ​​for the controller parameters on-line. Types of Self Adaptive Control Model Reference Adaptive Control (MRAC). Self Tuning Regulator (STR). Model Reference Adaptive Control  Model Reference Adaptive Control is also known as the MRAC. Basically  process parameters are unknown or vary with time, an adaptive control scheme known as the model reference adaptive control (MRAC) is applied to achieve as well as ma...

What is an instrument?  Essentially, an instrument is a technology used to measure and control a process variable known as an instrument. And it is a device that is used to measure, monitor, display, etc. a process variable. The basic process variables in an instrument are pressure, flow, level and temperature. Pressure   Generally pressure is defined as force per unit area and mathematically known as pressure = F/A. And the unit of pressure is PSI, BAR, PASCAL, TORR, Kg/cm  Flow   Usually flow is defined as the rate of change of differential pressure. And the unit of flow is liter/minute, gallon/hour, kg/hour.  Level Level is basically the difference between two heights. And the level unit is mm, meter, centimeter, MMWC (millimeter water column).

Characteristics of Measurement Essentially the instruments used for measurement have  characteristics such as accuracy, repeatability, sensitivity, display. Accuracy   Basically, accuracy is defined as the difference between the instrument's reading and its actual reading or measured value. and is expressed as a percentage of the top scale value regardless of where the scale reading is taken. Repeatability   The repeatability of an instrument means that the instrument will give the same reading on the scale regardless of how the measurement point is reached. It means fast or slow, high or low. If the instrument reads 49 instead of 50 on the upper scale, it should read the same on the downscale reading. If it reads 51 units, the error is called hysteresis, which is caused by frictional losses. Sensitivity   Sensitivity of an instrument is its ability to respond to a small change in the value being measured. This is the smallest change that will result in effective mot...

Analytical Instrumentation  MCQ 1. Lambert’s law states that the intensity of light decreases with respect to __________ a) Concentration b) Distance c) Composition d) Volume Answer: Distance 2. Beer’s law states that the intensity of light decreases with respect to ___________ a) Concentration b) Distance c) Composition d) Volume Answer: Concentration 3. Which of the following detectors does not require a battery and is also known as barrier layer cell? a) Photomultiplier tube b) Photovoltaic cell c) Photoemissive tubes d) Photo reflector Answer: Photovoltaic cell 4. Which of the following is not a type of Spectroscopy? a) Gamma ray b) X ray c) Nuclear magnetic resonance d) Sound Answer: Sound 5. How is Tungsten Halogen lamp differs from normal Tungsten filament lamp used in absorption spectroscopy? a) It has a tungsten filament and is filled with inert gas b) Iodine is added to normal filling gas c) Iodine is coated on tungsten filament d) Iodine is added to inert gas Answer: Iod...

P&ID Symbols PC = Pressure Controller PI = Pressure Indicator PR = Pressure Recorder  PIC = Pressure Indicating Controller  PRC = Pressure Recording Controller  PSV = Pressure Safety Valve PT = Pressure Transmitter RV = Relief valve LA = Level Alarm LAH = Level Alarm High LAL = Level Alarm Low LC = Level Controller LG = Level Glass LI = Level Indicator LIC = Level Indicating Controller LRC = Level recording Controller FC = Flow Controller  FE = Flow Element  FA = Flow Alarm FE = Flow Element FI = Flow Indicator FR = Flow Recorder FRC = Flow recorder Controller FIC = Flow Indicator Controller LC = Level Control LG = Level Gauge LA = Level Alarm LAH = Level Alarm High LAHH = Level Alarm High High LI = Level Indicator LIC = Level Indicator Controller TA = Temperature Alarm TI = Temperature Indicator TR = Temperature recorder TRC = Temperature recorder Controller TW = Temperature Well TY = Temperature Relay TW = Thermowell HCV = Hand Control Valve SDV = Shut Dow...

Variable Frequency Drive  Basically, variable frequency drive is also known as AC drive as well as variable speed drive (VSD). And it is commonly used in industry because of its low cost. A VFD (Variable Frequency Drive) is a type of motor control that drives an electric motor by varying the frequency and voltage of its power supply. The VFD also has the ability to control the ramp-up and ramp-down of the motor during start or stop respectively. VFD is widely used in industries like food and beverage industry, automotive industry, food industry, chemical industry, textile industry, paper industry, wood industry, metal industry. Applications of Variable Frequency Drives   VFDs are used for different types of machines like Boring / Cutting Machine Grinder  Crunchers Mixer  Conveyors  Wind tunnels  Pump  Fans 

Instruments Basically an instrument is a man made device which is used to measure a parameter of a physical variable. And it is variable analog as well as digital or a combination of digital and analog. Generally most industrial instrument is digital because digital instrument has more advantages compared to analog instrument . But in most cases the front end instrument is still analog and most signals from sensors or transducers are analog . Most sensors have the form of a chip and this smart sensor is directly connected or digital devices. The most basic and elementary components in all devices are sensors and transducers. Basically these outputs are current, voltage and power or amplitude, frequency or phase difference of energy. And all devices operate on signals. A signal is detected by a sensor from physical phenomena. The difference between analog and digital instruments is signal processing, and it requires different theoretical approaches and hardware. You may also like this: ...