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 usu...

  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 a...

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...