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Technical Reference 

The Technical Reference section includes articles covering regulator theory, sizing, selection, overpressure protection, noise, freezing, and other topics relating to regulators. If there is something you need to know about a regulator that is not covered, please contact the local Sales Office in your area.

Regulator Control Theory
Regulator Components
Introduction to Regulators
Principles of Operations & Regulator Sizing Theory
Vacuum Control
Valve Sizing (Standardized Method)
Temperature Considerations
Sulfide Stress Cracking
Complete Technical Section

NOTE: Although compressed in the Acrobat PDF format, some of our documents are extremely large and download times may be significant. One option for most current browsers is to right-click on the document title, which allows you to save the document to a location on your computer rather than opening the file. All PDFs contain bookmarks for ease of navigation through the sections.


 REGULATOR CONTROL THEORY:  Fundamentals of Gas Pressure Regulators, Pilot-Operated Regulators. 

 REGULATOR COMPONENTS:  Section contains diagrams of Straight Stem Style Direct-Operated, Lever Style Direct-Operated, Loading Style Pilot-Operated, Unloading Style Pilot- Operated Regulators.

 INTRODUCTION TO REGULATORS:  Instrument engineers agree that the simpler a system is the better it is, as long as it provides adequate control. In general, regulators are simpler devices than control valves. Regulators are self-contained, direct-operated control devices which use energy from the controlled system to operate whereas control valves require external power sources, transmitting instruments, and control instruments.  

 PRINCIPLES OF OPERATIONS & REGULATOR SIZING THEORY:  Regulators provide a means of controlling the flow of a gas or other fluid supply to downstream processes or customers. An ideal regulator would supply downstream demand while keeping downstream pressure constant; however, the mechanics of direct-operated regulator construction are such that there will always be some deviation (droop or offset) in downstream pressure.  

 VACUUM CONTROL Vacuum regulators and vacuum breakers are widely used in process plants. Conventional regulators and relief valves might be suitable for vacuum service if applied correctly.  

 VALVE SIZING (STANDARDIZED METHOD):  Fisher regulators and valves have traditionally been sized using equations derived by the company. There are now standardized calculations that are becoming accepted world wide. Some product literature continues to demonstrate the traditional method, but the trend is to adopt the standardized method.  

 TEMPERATURE CONSIDERATIONS:  Freezing has been a problem since the birth of the gas industry. This problem will likely continue, but there are ways to minimize the effects of the phenomenon. 

 SULFIDE STRESS CRACKING:  NACE MR0175, “Sulfide Stress Corrosion Cracking Resistant Metallic Materials for Oil Field Equipment” is widely used throughout the world. In late 2003, it became NACE MR0175/ISO 15156, “Petroleum and Natural Gas Industries - Materials for Use in H2S-Containing Environments in Oil and Gas Production”.  These standards specify the proper materials, heat treat conditions and strength levels required to provide good service life in sour gas and oil environments.

 REFERENCE:  This section contains information regarding elastomers, metals, regulator tips, conversions, equivalents, and physical data.

 GLOSSARY:  Glossary of regulator terms for reference.

 COMPLETE TECHNICAL SECTION Download the complete Technical Section tabbed with bookmarks.