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Control Global features news and analysis of process control and automation technology to help managers and engineers maintain and optimize systems for today's process industries.
How to size and select your next pressure relief valve
Nov 4, 2020 · How to size and select your next pressure relief valve. Nov. 4, 2020. Thorough understanding of process dynamics is needed to ensure reliable operation of these ‘last line of defense’ devices. Ghulam Farooq. A pressure relief valve (PRV) is a safety device designed to protect a pressurized vessel or system in case of an overpressure event.
Understanding switch configurations - Control Global
Nov 25, 2019 · A: NO and NC are the fundamental blocks of understanding any logic, be it soft or hardware. Normal condition is defined as energized condition and when plant/equipment/machine is running in normal condition, logic is true. NC means normally-closed contact. NO means normally-open contact.
A straightforward explanation of feedforward control
Jun 9, 2020 · The ISA Mentor Program “Feedforward and Ratio Control” webinar including a Q&A addendum has an intensive steam system example and gives concepts of ratio control including automated adaptation of the ratio setpoint or bias to minimize the feedback correction. Slide 6 provides considerable understanding of why experts use feedforward summers or multipliers.
Automatic tank gauging 101 - Control Global
Mar 15, 2021 · Automatic tank gauging 101. March 15, 2021. From measurement accuracy to lifecycle costs, the key considerations to keep top of mind. Keith Larson. The purpose of tank gauging is to measure the contents of tanks and vessels for inventory control and custody transfer. Most process plants have tanks that hold feedstock or finished products, and ...
Dos and don'ts of control room design | Control Global
Apr 26, 2019 · A control room that has no room for future expansion of people or equipment. Control rooms with poor lighting, leading to employee complaints and higher rates of absenteeism. Noisy, congested control rooms with sub-optimal workflow adjacencies. Delays in design and construction schedules required to address changes.
How history, principles and standards led to the safety PLC
May 17, 2016 · The SIL 1 safety system is the most commonly used, and provides risk reduction in the range from 10:1 to 100:1. In the process industries, the highest SIL rating normally used is SIL 3. SIL 4 is only used under very special circumstances such as nuclear plants. SIL levels 1 to 3 represent a coarse scale of safety performance for the SIS.
How valve failure modes interact with controller actions and …
Dec 9, 2021 · The controller action is selected for the total loop (Figure 1) to always have negative feedback (RA). Each RA (180° phase shift) in the loop causes a sign reversal, while each DA results in no phase shift. In terms of the total loop, this means that if both the valve and the process are DA (phase shift = 0) or if both are RA (phase shift -180 ...
Signal filtering: Why and how - Control Global
Jul 24, 2019 · Greg McMillan. Filtering is the modification of a measured or calculated signal—using an algorithm and/or logic—to remove undesirable aspects of the signal before it is used in a calculation or a controller. Examples in control are the feedback (or controlled) variable to a PID or APC controller, or the input to a feedforward controller.
Sizing and checking equal-percent control valves
Oct 20, 2022 · It's a 10-year-old equal-percent control valve. Installation and testing data is included in the accompanying graphics. The control valve outlet piping is around 2.0 m vertically upward, connecting to the nozzle entering the distillation column. The check valve is functioning and the gate valve is fully open. There's also no pipe clogging issue.