Inst ToolsInst ToolsInst Tools
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Search
  • Books
  • Software
  • Projects
  • Process
  • Tools
  • Basics
  • Formula
  • Power Plant
  • Root Cause Analysis
  • Electrical Basics
  • Animation
  • Standards
  • 4-20 mA Course
  • Siemens PLC Course
Reading: Identify the Pressure Gauge Error
Share
Font ResizerAa
Inst ToolsInst Tools
Font ResizerAa
  • Courses
  • Design
  • PLC
  • Interview
  • Control System
Search
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Inst Tools > Blog > Practical Questions > Identify the Pressure Gauge Error

Identify the Pressure Gauge Error

An operator claims pressure gauge is defective and needs to be replaced. The pressure controller and gauge readings are different.

Last updated: September 7, 2020 5:05 pm
Editorial Staff
Practical Questions Pressure Measurement
No Comments
Share
3 Min Read
SHARE

An operator claims pressure gauge PG-108 is defective and needs to be replaced. This pressure gauge registers 50 PSI, while pressure controller PIC-33 and pressure recorder PR-33 both register the pressure as being equal to setpoint: 43 PSI.

Before replacing this pressure gauge, however, you decide to do some diagnostic thinking to see if there might be other causes for the abnormally high reading at PG-108.

The first thing you check is the position of control valve PV-33a, and you find its stem position to be at 35% open.

Identify the Pressure Gauge Error

Identify the Pressure Gauge Error

Identify the likelihood of each specified fault in this process. Consider each fault one at a time (i.e. no coincidental faults), determining whether or not each fault could independently account for all measurements and symptoms in this process.

Identify the below faults are possible or impossible?

  • PG-108 calibration error
  • PT-33 calibration error
  • PIC-33 left in manual mode
  • PY-33a calibration error
  • PY-33b calibration error

Finally, identify the next diagnostic test or measurement you would make on this system. Explain how the result(s) of this next test or measurement help further identify the location and/or nature of the fault.

Answer:

The fact that the gauge disagrees with both the recorder and the controller tells us the problem is either with the gauge or with the transmitter. Nothing else (controller mode, valve signal path, PY-33a) could cause this to happen.

Therefore, valid tests include anything to help us discern whether there is a problem in the gauge, in the transmitter, in the resistor, or in the controller’s PV input.

  • PG-108 calibration error – Possible
  • PT-33 calibration error – Possible
  • PIC-33 left in manual mode – Impossible
  • PY-33a calibration error – Impossible
  • PY-33b calibration error – Impossible

More Questions:

  1. Based on the information you have at this point, can you tell whether any suspected calibration error is due to a misadjustment of zero or of span? Explain why or why not.
  2. Is controller PIC-33 direct-acting or reverse-acting? How can you tell?
  3. Does control valve PV-33a throttle gas or liquid? How can you tell?
  4. Identify a typographical error in this P&ID.
  5. A useful diagnostic technique for identifying which instrument is miscalibrated is to compare the readings of multiple instruments (all sensing the same process variable) to see which one of them disagrees most with the others. May we apply this technique to the problem at hand? If so, which instrument readings should we compare? If not, explain why not.

Share your answers with us through the below comments section.

Read Next:

  • Loop Diagram Questions
  • Faults in a Transformer
  • Control Loop Questions
  • Pressure Control Loop
  • Problem with Pirani Gauge

Credits: Tony R. Kuphaldt

Don't Miss Our Updates
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
Invalid email address
You've successfully subscribed !

Continue Reading

Pressure Transmitter Preventive Maintenance
Motor Trip Logic using PLC Programming
Pressure Gauge Selection
Importance of Temperature in Remote Seal Pressure Transmitter
Identify Two Pressure Switches Logic
Questions on Pneumatic Transmitter and Repeater
Share This Article
Facebook Whatsapp Whatsapp LinkedIn Copy Link
Share
Leave a Comment

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Stay Connected

128.3kFollowersLike
69.1kFollowersFollow
210kSubscribersSubscribe
38kFollowersFollow

Categories

Explore More

PLC Practice Questions
Impulse Line Purging and Close Coupling of Instruments
Calculate the Thermocouple Output millivolts
5 Valve Manifold Operation
Electronic Pressure Sensors Principle
Baffle Nozzle Question
Calculate PSV Lift Pressure
Draw a ladder logic circuit for the electric motor of an air compressor ?

Keep Learning

Inductive proximity switches

How to Connect Proximity Switch (Sink Type) to Make LED ON ?

Commissioning Differential Pressure Transmitter in Boiler Steam Drum

Commissioning a Differential Pressure Transmitter in a Pressurized Boiler Steam Drum

Effects of Capillary Tubing on Pressure Measurement

Capillary Tubing Pressure Sensor Temperature & Elevation Problems

Programmable Logic Controller (PLC) Questions and Answers

Programmable Logic Controller (PLC) Questions and Answers – 5

Solenoid Valves Questions

Solenoid Valves Questions & Answers – 3

Air Pressure Regulator cut-away diagram

Air Pressure Regulator Questions

DP Transmitter Problem

DP Transmitter Problem

Calculate Total Hydrostatic Pressure at Bottom of Vessel

Calculate Total Hydrostatic Pressure at Bottom of Vessel

Learn More

Instrument Ranging

Notes on Instrument Ranging

Guided Wave Radar Questions and Answers

Guided Wave Radar Questions and Answers

Classification of Bridge Circuits

Classification of Bridge Circuits

Types of active transducers

Types of Transducers in Instrumentation

Target Flow Transmitter Problem

Target Flow Transmitters Failed the Very Midnight

What is Open Telemetry?

What is Open Telemetry? – Principles and Benefits

Electrical & Electronics Measurements Objective Questions

Electrical & Electronics Measurements Objective Questions – Set 4

Monsoon Protection for Field Instruments and Junction Boxes

Monsoon Protection for Field Instruments and Junction Boxes

Menu

  • About
  • Privacy Policy
  • Copyright

Quick Links

  • Learn PLC
  • Helping Hand
  • Part Time Job

YouTube Subscribe

Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Welcome Back!

Sign in to your account

Username or Email Address
Password

Lost your password?