Logic Gates
The word “discrete” means individual or distinct. In engineering, a “discrete” variable or measurement refers to a true-or-false condition. Thus, a discrete control system is one designed to operate on…
Pre-Startup Safety Review (PSSR)
The term Prestartup Safety Review (PSSR) first received prominence in the process industries with the introduction of the Process Safety Management (PSM) regulations. In the United States two federal agencies,…
Siemens Pressure Transmitter with Remote Seals Calculations
Remote seals of sandwich design are fitted between the connection flange of the measuring point and a dummy flange. Remote seals of flange design are fitted directly on the connection…
Gage and Absolute Pressure Transmitters Principle
Gage and Absolute Pressure Transmitters : Sensor Design for Gage Pressure Measurement The input pressure (pe) is transferred to the gage pressure sensor (6) via the seal diaphragm (4) and…
Siemens Differential Pressure Transmitter Calculations (Flange Type)
Siemens Pressure transmitters / differential pressure Transmitters, for flange type (Without remote seal) The Transmitter Lower Range Value (LRV) and Upper Range Value (URV) calculations for a siemens pressure/differential pressure…
Standard Temperature and Pressure Conditions
Standard temperature and pressure conditions as well as normal temperature and pressure conditions are used as reference points in thermodynamics of gases. Normally standard and normal temperature pressure conditions are…
Why have been limits imposed on the frequency ratio for thermowells?
In 1995, an accident caused due to breaking thermowells in Monju Nuclear Plant reactor, led to very serious damages to the surrounding facilities. Thermowells located on a line carrying liquid…
NFPA Standards (National Fire Protection Association Standards)
NFPA standards from National Fire Protection Association provide guidelines for incorporating fire protection safety measures in industrial systems. Classification of Fire and Hazard as per NFPA - The National Fire Protection…
Motor Control Circuit Wiring
A simple three-phase, 480 volt AC motor-control circuit is shown here, both in pictorial and schematic form. This entire assembly consisting of contactor, overload block, control power transformer, power fuses…
Motor Protection Circuits
An essential component of any high-power motor control circuit is some device to detect a condition of excessive overload and interrupt power to the motor before thermal damage occurs. A…
