the company i work for is having the guy that is on call on friday give a class,well i'm on call this friday and would like as much info on pneumatics,since i don't know that much about it,websites,manuals etc.
thanks for any help
"Open is as open does."
- Forrest Gump
"Can't we all just get a Lon?"
- Garry Jack
"BACnet: integration or interrogation?"
- The Janitor
"Open protocols? You can't handle open protocols!"
- Nathan R. Jessup
“What’s that? Aaa… open protocols? Don’t talk about…. open protocols? Are you kidding me? Open protocols? I just hope we can hardwire an interface!”
- Jim Mora http://www.youtube.com/watch?v=U7fjDS0jKiE
Pneumatic Control Terms
Pneumatic Control Terms
Controller – A device that receives an input from a sensor and outputs the appropriate signal.
Controlled Variable – The substance that your trying to maintain, temperature, humidity, air flow etc…
Controlled Device – Normally an actuator which operates a valve or damper. Could be an input to another controller.
Throttling Range – The total change of the controlled variable required to move the controlled device fully.
Sensor – (Transmitter) A device that measures the controlled medium, air , water, humidity, etc…
Range – The actual parameters of a sensor or transmitter, 0 – 100 F, 0.5” Wc – 1.5” Wc, 5% - 95% RH.
Span – The difference between the low and high ranges.
Sensitivity – Change in pressure per unit change.
Thermostat – Built in sensor combined with controller.
Single Input Controller – A controller with one remote sensor or transmitter.
Dual Input Controller – A controller with two remote sensors or transmitters.
Proportional Band – The percentage of the sensor span used to generate a change in the output of the controllers P-Man.
P-Man – Pressure of the manufacturer, Powers – 5 PSI, Honeywell – 10 PSI, Robertshaw 13 PSI.
Authority – The amount of control the reset controller has on a dual input controller.
Gain – Johnson Control term to equate the comparison of a 1 PSI input change to output relationship.
Ratio – Johnson Control term to express the control the reset loop has on the primary loop in percentage.
Law Of The Thermostat: He who has the thermostat wins!!!!!
Robertshaw puts out a booklet on basic pneumatics. Don't remember what its called but it is brown & tan. Very easy reading!
Last edited by HVAC Teacher; 03-05-2007 at 01:05 PM.
Simlpe and basic start
Instead if using electricity to control or move something mechanical or mechanical/electrical, you use pneumatic air. You have a constant air pressure say 20 PSI that goes to some type of device, we will say T = thermostat. The T senses a temperature change and the constant air 20 PSI going into the T is regulated and aloud to pass through the T and back out to a piece of equipment at a regulated amount say 3 PSI. The equipment could be a valve. The 3 PSI leaving the T starts to stroke the valve to a position that either heats or cools as the demand changes the PSI also changes in turn the valve changes.
Try this textbook, 8 chapters on multimanufacturer pneumatics, with lots of photos, calibration procedures, etc. Also has a CD w/quizzes
Not many of those left around here but I will send you one if you give me a ship to address....
Originally Posted by HVAC Teacher
Invensys Robertshaw Ranco RAM Fenwal Eliwell & some Paragon