Summary post of weekly questions from 2011

This post was last edited by denghl on 2012-12-21 at 21:59. We strongly support the implementation of one question per week, and it will be put into effect soon. A summary of the questions for each week is as follows: Week 1, 2011 – Issues related to discrepancies between on-site indications from orifice plates and those from DCS systems; Week 2, 2011 – Determining the forward or reverse action mode of regulators in reheating furnace cascade control systems; Week 3, 2011 – Experience in using on-site level gauges; Week 4, 2011 – Problems associated with using instruments in highly toxic environments; Week 5, 2011 – Issues where control valve positioners fail to provide output; Week 6, 2011 – Reverse operation direction of air-operated control valves; Week 7, 2011 – Why DC signal systems are commonly used in industrial automation instruments; Week 8, 2011 – Can air-operated ball valves be installed vertically?; Week 9, 2011 – Deformation of the drive rod of air-operated ball valves when installed vertically; Week 10, 2011 – What precautions should instrument technicians take during on-site work? Week 11, 2011: Introduction to the types of instruments I have worked with and my experience in their maintenance. Week 12, 2011: What are the calibration intervals and standards for instrument calibration? Week 13, 2011: The cost-effectiveness of various types of flow meters. Week 14, 2011: Question of the week – Week 14, 2011: What are absolute error, relative error, and reference error? Week 15, 2011: Is the calibration range of an instrument the same as its measurement range? Why? Week 16, 2011: Steps to start a differential pressure transmitter for flow measurement. Week 17, 2011: How to choose the positive or negative action mode of a regulator? (Single circuit) Week 18, 2011: How to operate the instrument three-valve assembly? What should be noted? Week 19, 2011: What conditions must be met for something to serve as an object of automatic regulation? Week 20, 2011: What are the main calibration parameters of a regulator? Sharing work experience – Week 21, 2011: How do cascade control systems compensate for nonlinear characteristics? Week 22, 2011: How to design an I/ASeries system? Week 23, 2011: Why are 4–20mA current signals used for communication between the field and the control room in some instruments, while 1–5V voltage signals are used within the control room? Week 24, 2011: The temperature gauge shows inaccurate readings – how to determine the issue? Week 25, 2011: Flow measurement using orifice plates – why is it reasonable to install the orifice plate in front of the control valve? Week 26, 2011: What is isolation? Under what circumstances should isolation be used for measurement? Week 27, 2011: Why do wires or electrical components heat up when a large current flows through them, and why are they prone to burning out? Week 28, 2011: Why is cold-junction compensation necessary when using thermocouples for temperature measurement. Week 29, 2011: Is there any specification regarding the length of the pressure tapping tubes? What length is considered optimal? Week 30, 2011: What is a pressure thermometer, and on what principle does it work? Week 31, 2011: Why are the sensing elements of differential pressure transmitters designed as diaphragm boxes? Is a single diaphragm sufficient? Week 32, 2011: What is the effective value of sinusoidal alternating current? Week 33, 2011: Issues related to the thermoelectric properties of compensation wires and thermocouples. Week 34, 2011: Installation requirements for electric actuators. Week 35, 2011: Describe the working principle of valve positioners as shown in the diagram. Week 36, 2011: What requirements must be met when using water heating? Week 37, 2011: What are the requirements for steam tracing? Week 38, 2011: What are the functions of valve positioners? Week 39, 2011: What are open-loop and closed-loop control systems? Week 40, 2011: In-depth discussion on experiences in preventing freezing of instrument pipelines. Week 41, 2011: What is random error? What is gross error? What are its causes and characteristics? Week 42, 2011: What considerations should be taken when installing flanges? Week 43, 2011: Issues related to the installation of differential pressure instruments or transmitters. Week 44, 2011: The issue of hysteresis in instrument calibration. Week 45, 2011: What are the general methods for pressure measurement? Week 46, 2011: How are the forward and reverse actions of actuators and regulators defined? Week 47, 2011: The roles of P, I, and D in PID control. Week 48, 2011: Discussion on the stability issues of control valves. Week 49, 2011: What considerations should be taken when calibrating control valves after maintenance? Week 50, 2011: What are the differences between feedforward control systems and feedback control systems?

The weekly question in the instrumentation area is really good. Based on my experience, the measurement accuracy and lifespan of instruments are influenced not only by their inherent performance but also by factors such as the installation location and the surrounding environment. Therefore, I recommend that experts in automation engineering communicate with professionals from other fields to achieve a win-win situation.

I work in the instrumentation field too; I’ll keep it for future use! Those who need it can get in touch with me. Oh! ! ! !

Collected it~ dug a big grave~:D