Sensors and Transmitters (APM02)

This comprehensive INVOLVE?? interactive multimedia training program was produced in association with the Instrument Society of America (ISA).

This three lesson 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.

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.