industrial instrumentation basics

Control Valve  What is a control valve A control valve is an instrument that regulates the flow of fluids (oil, water, or gases) as the valve position is changed by moving the stem with help of an actuator. This actuator may be a motor of a pneumatic or hydraulic jack.  The control valve is the most commonly used final control equipment in the control loop of an industrial process. The control valve receives a control signal as input from plc or DCS, a controller is used to compare the setpoint and control valve actual position and then decides to open or close the valve according to match the set point. Classes of  Control Valve on the base of motion Two main types of valves are according to the motion of the stem. 1. Linear motion  2. Rotary motion 1. Linear motion  Linear motion is a movement of valve stem up and down, a common type of linear motion control valve is the Gate valve. 2. Rotary motion  A rotary motion valve moves or rotates at an angle usually 90 degrees, common type

  Load Cell A load cell is a transducer that is used to measure force. The load cell is mostly an electromechanical transducer that converts mechanical energy into electrical energy. The load cell measures static and dynamic forces acting on it. The load cell is consists of an elastic material that deforms according to the force it receives. The magnitude of this deformation of elastic material is proportional to the magnitude of the force acting on it. Normally strain gauges are used in the load cell. Load cell types according to working principle Following methods are used in load cells to measure forces. 1. Strain gauges load cell  2. Hydraulic load cell 3. Pneumatic load cell 4. Capacitive load cell 5. piezoelectric load cell 1. Strain gauge load cells   Load cells are used in different industrial applications to measure force or weight. Load cells are made up of strain gauges and a Wheatstone bridge is used to measure the force acting on the load cell. Load Cells are made up of

Capacitive Type Level Sensors Capacitive type level switches and transmitters are widely used in industrial level measurements. The capacitor is made up of two plates and isolated by some isolators having a fixed dielectric constant. But in level measurement we use a variable capacitor, capacitance can be changed by changing the gap between the two plates or by changing the dielectric constant, so dielectric constant changes and proportional to that capacitance also changes. Capacitive level switches  Capacitive level switches are used in industrial applications for the point-level sensor to detect a high or low level of a vessel or tank. Working principle of capacitive level switch  In capacitance type level switches, there are two main units: 1. Capacitive probe 2. controller  The capacitive probe is made up of two plates mostly in the shape of two rods. and the material we want to sense acts as a gap between the plates.  As material touches, the sensor probe, the dielectric constan

 Instrumentation Interview Questions and Answers Instrumentation Interview Questions and Answers There are different questions that you can be asked in an interview for the post of instrument technician, instrumentation engineer, or instrument supervisor. Most interview questions are related to the industry you are going to apply to, and they prefer a skilled person and have a good knowledge of instruments used in that specific industry. Here I will try to write the question with answers that are mostly asked for instrumentation professionals. Q. No. 1:  What is instrumentation? Ans :  Instrumentation is a branch of science which deals with the measurement and control of process variables in a process. Q. No. 2  What is the process? Ans :  The process is defined as the adoption of series of steps or methods to acquire a predefined result. Q. No. 3  What is a process variable? Ans :  It is a variable in the process that we are attempting to maintain, measure or control in a process.

  Radar Level Transmitter Vs Ultrasonic Level Transmitter  Here is a brief comparison of the ultrasonic level transmitter and radar level transmitter: MEASUREMENT PRINCIPLE  Ultrasonic level transmitter working principle is based on Sound or acoustic Waves transit time,  while Radar level transmitter uses  High-Frequency Radar Impulses to measure the level of medium.  Vacuum Applications Ultrasonic level measurement  required a medium that Sound must travel through a medium (usually air) because The absence of air molecules prevents the propagation of sound waves  while Radar level transmitter   Radar has no such issue of wave propagation and radar waves can travel through a vacuum. Surface Condition Angles  Sound waves must be sent and received in a straight line  Reflective surfaces must be flat (i.e. Non-agitated and Non-turbulent condition), no angel issue in Radar level measurement. Irregularities  In ultrasonic level sensor Foam and other debris collected on the surface of the l