What is Weighfeeders ?

A special type flowmeter suited for powdered or granular solids is the weighfeeder. One of the most common weighfeeder designs consists of a conveyor belt with a section supported by rollers coupled to one or more load cells, such that a fixed length of the belt is continuously weighed: The load cell measures the weight of a… Read More »

How to speed control of DC motor ?

DC electric motors generate torque by a reaction between two magnetic fields: one field established by stationary “field” windings (coils), and the other by windings in the rotating armature. Some DC motors lack field windings, substituting large permanent magnets in their place so that the stationary magnetic field is constant for all operating conditions. In any case, the… Read More »

What is Characterized valve trim ?

The root cause of the problem – a varying pressure drop caused by frictional losses in the piping and other factors – generally cannot be eliminated. This means there is no way to regain maximum flow capacity short of replacing the control valve with one having a greater Cv rating. However, there is a clever way to flatten… Read More »

How to calibrate an RTD ?

Introduction:- There are two types of calibrations applicable to PRTs—characterization and tolerance testing. The type of calibration to perform is determined by the way in which the UUT is to be used and the accuracy required by the user. Characterization is the type of calibration in which the unit under test (UUT) resistance is determined at several temperature points… Read More »

Ratio control

Most people  have likely had the experience of adjusting water temperature as they took a shower with dual valves: one valve controlling the flow of hot water and another valve controlling the flow of cold water. In order to adjust water temperature, the proportion of one valve opening to the other must be changed. Increasing or decreasing total… Read More »

Supervisory control

In a manually-controlled process, a human operator directly actuates some form of final control element (usually a valve) to influence a process variable. Simple automatic (“regulatory”) control relieves human operators of the need to continually adjust final control elements by hand, replacing this task with the occasional adjustment of setpoint values. The controller then manipulates the final control element… Read More »