Inst ToolsInst ToolsInst Tools
  • Ask
  • Courses
  • Videos
  • Q & A
    • Interview
      • Instrumentation
      • Electronics
      • Electrical
      • Practical Questions
    • MCQ
      • Instrumentation MCQ
      • Electrical MCQ
      • Electronics MCQ
      • Control Systems MCQ
      • Analog Electronics MCQ
      • Digital Electronics MCQ
      • Power Electronics MCQ
      • Microprocessor MCQ
      • Multiple Choice Questions
  • EE
    • Electronics
      • Electronics Q & A
      • Electronic Basics
      • Electronic Devices & Circuits
      • Electronics Animation
      • Digital Electronics
    • Electrical
      • Electrical Basics
      • Electrical Q & A
      • Power Electronics
      • Electrical Machines
      • Electrical Animation
      • Power Systems
      • Switchgear & Protection
      • Transmission & Distribution
  • Measure
    • Control Valves
    • Calibration
    • Temperature
    • Pressure
    • Flow
    • Level
    • Analyzers
    • Switches
    • Vibration
    • Solenoid Valve
  • Control
    • PLC Tutorials
    • Control Systems
    • Safety Instrumented System (SIS)
    • Communication
    • Fire & Gas System
  • More
    • Design
    • Tools
    • Animation
    • Basics
    • Formulas
    • Standards
    • TextBooks
    • Common
    • Software
    • Excel Tools
    • Erection & Commissioning
    • Process Fundamentals
    • Videos
    • Books
Search
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Reading: Pilot-operated Safety and Relief Valves
Share
Notification Show More
Font ResizerAa
Inst ToolsInst Tools
Font ResizerAa
  • Courses
  • PLC Tutorials
  • Control Systems
Search
  • Ask
  • Courses
  • Videos
  • Q & A
    • Interview
    • MCQ
  • EE
    • Electronics
    • Electrical
  • Measure
    • Control Valves
    • Calibration
    • Temperature
    • Pressure
    • Flow
    • Level
    • Analyzers
    • Switches
    • Vibration
    • Solenoid Valve
  • Control
    • PLC Tutorials
    • Control Systems
    • Safety Instrumented System (SIS)
    • Communication
    • Fire & Gas System
  • More
    • Design
    • Tools
    • Animation
    • Basics
    • Formulas
    • Standards
    • TextBooks
    • Common
    • Software
    • Excel Tools
    • Erection & Commissioning
    • Process Fundamentals
    • Videos
    • Books
Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Inst Tools > Blog > Control Valves > Pilot-operated Safety and Relief Valves

Pilot-operated Safety and Relief Valves

Last updated: March 28, 2019 4:12 pm
Editorial Staff
Control Valves Safety Instrumented System (SIS)
No Comments
Share
4 Min Read
SHARE

While many safety and relief valves actuate by the direct action of the process fluid forcing against the valve plug mechanism, others are more sophisticated in design, relying on a secondary pressure sensing mechanism to trigger and direct fluid pressure to the main valve assembly to actuate it.

Contents
Pilot-operated Safety and Relief ValvesComparison to non piloted pressure relief valvesAdvantagesDisadvantagesArticles You May Like :Pneumatic InstrumentationPressure Transmitter ManifoldsInsertion flow metersWhat is Magnetic Tape Recorder ?P&ID for Pumps Heat ExchangersDe-energize to Safe Loop philosophy

This pressure-sensing mechanism is called a pilot, and usually features a widely-adjustable range to give the overall valve assembly a larger variety of applications.

In a pilot-operated over-pressure-protection valve, the “lift” pressure value is established by a spring adjustment in the pilot mechanism rather than by an adjustment made to the main valve mechanism.

Pilot-operated Safety and Relief Valves

A photograph of a pilot-operated pressure relief valve used on a liquid petroleum pipeline appears here:

Pilot-operated Safety and Relief Valves

This photograph courtesy of the National Transportation Safety Board’s report of the 1999 petroleum pipeline rupture in Bellingham, Washington. Improper setting of this relief valve pilot played a role in the pipeline rupture, the result of which was nearly a quarter-million gallons of gasoline spilling into a creek and subsequently igniting.

One of the lessons to take from this event is the importance of proper instrument maintenance and configuration, and how such technical details concerning industrial components may have consequences reaching far beyond the industrial facility where those components are located.

The relief valve mechanism itself is the white-painted flanged valve found in the center-right region of the photograph (RV-1919). This particular relief valve happens to be a Fisher model 760 with 8-inch, ANSI 300# flanges.

The actuating pilot mechanism is the small unit connected to the relief valve body via stainless-steel tubing. When this pilot senses fluid pressure in the pipeline exceeding the lift pressure, it switches fluid pressure to the piston actuating mechanism of the main relief valve, opening it to relieve fluid pressure from the pipeline.

Thus, the lift pressure value for the relief valve is set within the pilot rather than within the main valve mechanism. Altering this lift pressure setting is a matter of adjusting spring tension within the pilot mechanism, and/or replacing components within the pilot mechanism.

Comparison to non piloted pressure relief valves

Advantages

  • Smaller package on the larger pipe sizes.
  • More options for control.
  • Seals more tightly as the system pressure approaches but does not reach set pressure.
  • Control pilot can be mounted remotely.
  • Some designs allow for changes in orifice size within the main valve.
  • Can be used in engines.

Disadvantages

  • More complex, resulting in various fail-open failure modes.
  • More expensive at smaller sizes (starts to even out as pipe size increases).
  • Small parts in pilot valve are sensitive to contaminant particles.

Articles You May Like :

Pneumatic Instrumentation

Pressure Transmitter Manifolds

Insertion flow meters

What is Magnetic Tape Recorder ?

P&ID for Pumps Heat Exchangers

De-energize to Safe Loop philosophy

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 !
SIS Hardware Fault Tolerance – Methods to Overcome HFT issues
Air Pressure Regulator Questions
Control Valves Leakage Classifications
How Needle Valve Works ?
Self-actuated Temperature Regulator – Principle, Types, Advantages
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
208kSubscribersSubscribe
38kFollowersFollow

Categories

Recent Comments

  • MIHARITSOA Aina Sitraka on Top Non-PLC Certification Courses for Automation Professionals
  • Vaishnavi on Free Instrumentation Course for Trainee Engineers
  • anuj kapoor on DCS Program to Maintain Draft in Furnace
  • anuj kapoor on IoT based Smart Boiler Control System with Cloud PLC and SCADA

Related Articles

Fail-Close Valve

What is a Fail-Close Valve? – Advantages and Disadvantages

How Valve Positioners act as Cascade Control Systems in a Loop?

How Valve Positioners act as Cascade Control Systems in a Loop?

Control Valve Working Animation

Control Valve Working Animation

What is Instrument Air Manifold

What is Instrument Air Manifold ?

Difference Between Solenoid Valve and Motorized Valve

Difference Between Solenoid Valve and Motorized Valve

Summary of Valve Types Characteristics

Summary of Valve Types Characteristics

Direct Acting Control Valve Positioner

Pneumatic Valve Positioner Working Principle

Emergency Shutdown Valve

Emergency Shutdown Valve : Advantages

More Articles

Torque Measurement Objective Questions

Torque Measurement Objective Questions

Top 100 LabVIEW Projects for Engineering Students

Top 100 LabVIEW Projects for Engineering Students

Series - Wound DC Motor

Series-Wound Motor

Fire Detectors Working Principle

Basics of Fire Detection and Alarm System

RJ45 Connector Pins

How to make RJ45 cable

Power Electronics Objective Questions

Single-Phase Full Wave AC-DC Converter Quiz

SIS Audit & Assessment - Safety Instrumented System

SIS Audit & Assessment – Safety Instrumented System

Sensors Objective Questions

Sensors Objective Questions

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?