Pneumatic Maintenance

This comprehensive INVOLVE® interactive multimedia training program was produced in association with the Instrument Society of America. (ISA). This program trains participants in the theory of pneumatic instrumentation and the principles of operation, characteristics, and capabilities of components typically found in pneumatic control loops.

Audience: This program is excellent for training technicians, operators, control practitioners and engineers as well as for the multi-craft training needs of process and manufacturing facilities.

Pneumatic Principles


Prerequisites: This lesson is designed for participants familiar with test instruments and devices.Description:

Description: This lesson introduces the principles of pneumatic instrument operation and the terms force, pressure and compressibility are defined. The operation of pneumatic air supply system components, including compressors, dryers, filters and regulators is explained. System maintenance and testing is also taught. Filter cartridge replacement and regulator maintenance is demonstrated.

Objectives:

  • Define force as it applies to pneumatics
  • Define pressure as it applies to pneumatics
  • Define compressibility as it applies to pneumatics
  • State Pascal’s law as it relates to pneumatics
  • State Boyle’s law as it relates to pneumatics
  • State Charles law as it relates to pneumatics
  • State the ideal gas law as it relates to pneumatics
  • Discuss how and why pneumatics are used in the industry
  • Describe why pneumatic instruments have a limited transmission distance
  • Describe the purpose and operation of a booster
  • List the effects of contaminants on a pneumatic system
  • Identify types of filters and how they aid in removing suspended material in an air supply system
  • Prepare a filter for disassembly
  • Dissemble a fitter
  • Clean a filter
  • Reassemble a filter
  • Identify the basic operating theory of three types of dryers
  • Check the operation of an air dryer
  • Determine when and explain why dew point is measured
  • Identify the parts of a regulator
  • List the difference between a bleed-type and a nonbleed type regulator
  • Adjust output pressure on a regulator
  • Maintain a regulator

Sensors and Transmitters


Prerequisites: This lesson is designed for participants familiar with test instruments and devices.

Description: This lesson describes the features and operation of sensors used in pneumatic instruments, including Bourdon tubes, filled bulbs, diaphragm capsules and bellows. It teaches how both force and motion-balance pneumatic transmitters operate and how transmitter components, such as flapper/nozzles, relays and restrictors are cleaned and maintained.

Objectives:

  • State four common sensing elements used in pneumatic instruments
  • Describe how a diaphragm capsule operates
  • List some types of damage that will affect the accuracy of a diaphragm capsule
  • Describe how a Bourdon sensing element operates
  • List three shapes a Bourdon sensing element can take
  • List some types of damage that will affect the accuracy of a Bourdon tube
  • Describe how a filled bulb sensor operates
  • State some types of damage that will affect the sensing accuracy of filled bulb system
  • Identify the nozzle/flapper, relay, feedback element, and restrictor in a pneumatic instrument
  • Explain the operation of a basic pneumatic instrument
  • Explain the operation of a pneumatic relay
  • Describe how a force-balance pneumatic transmitter operates
  • Interpret a manufacturer’s schematic drawing of a pneumatic transmitter to describe its principle of operation and location of parts
  • List possible causes for a pneumatic transmitter to erroneously produce full output
  • List possible causes for a pneumatic transmitter to produce no output
  • Given a pneumatic transmitter, clean the nozzle and flapper
  • Given a pneumatic transmitter, clean the restrictor
  • Given a pneumatic transmitter, disassemble and repair the relay
  • Given a pneumatic transmitter, replace air supply filter screens
  • Given a pneumatic transmitter, replace the diaphragm capsule

Controllers and Recorders


Prerequisites: This lesson is designed for participants familiar with test instruments and devices.

Description: This lesson focuses on operation and maintenance of pneumatic controllers and recorders. The lesson teaches how the bellows, relays, links, and levers within a controller are configured to provide proportional, integral, and derivative control modes, both in direct and reverse action. Common maintenance practices are covered, including relay and restrictor cleaning and replacement, along with controller and recorder calibration.

Objectives:

  • Describe the function of a controller
  • Identify common components found in a controller and state the function of each
  • State the purpose of damping in pneumatic systems
  • Review proportional, integral, and derivative control modes
  • Describe the operating principle of the four bellows arrangement
  • Review proportional band and gain
  • Review offset and the difference between repeats per minute and minutes per repeat
  • Describe an appropriate application for each of the control modes
  • Define direct action and reverse action and give an example of where each would be used
  • List possible malfunctions in a controller and the probable causes
  • Check the operation of a controller
  • Remove a controller from service
  • Replace a relay in a proportionally-plus-reset controller
  • Clean an adjustable restriction from a reset assembly
  • Return a controller to service
  • Align and calibrate a proportional-plus-reset controller
  • Identify the components of a pneumatic recorder
  • Disassemble and clean a pneumatic recorder
  • Clean a chart drive motor
  • Replace a chart drive motor
  • Calibrate a pneumatic recorder