Air consumption for idle state bleed rates is typically published in the specs. For instance I used to use Honeywell's electropneumatic positioner and its bleed rate consumption was spec'd at 0.3 SCFM.
I got the table at the link below from a Siemens sales guy.
I agree with the previous post. We get this question a lot, but a total usage of the positioner is a tough number to find out. There are lots of factors, volume of the actuator, speed requirements, torque requirements..etc.
All positioner manufactures publish a bleed rate. This is the amount of air that a positioner is purging at steady state. In recent years this has become a hot topic in Industry, the reason being is the introduction of zero bleed positioners. In all honesty this can be good or it can be bad, let me explain.
If you have a clean environment and you are confident that there is minimal air leakage in your air system at your plant, a zero bleed positioner is just for you. However, if you have dirty air or the environment around your positioner is bad a spool valve positioner is the best choice. The reason why is that the purging of air at steady state or set point gives the positioner a positive pressure inside the unit, disallowing particles to come inside the unit and cause harm. An invisible force field is what I call it. Also if your air system is leaking or there are leaks through out the plant, saving consumed air at the positioner should not be the highest on the priority list.
Anyhow, we sell both kinds of positioners at www.vacaccessories.com. Feel free to take a look and call us, or email us with any questions.
Measuring Air a positioner consumes.
Re: Measuring Air a positioner consumes.
