Cooling An Overheating Pneumatic Positioner

Pneumatic positioner

What can you do when the pneumatic positioner in your high temperature application is overheating?  Call EXAIR!

Or email (and call), as was the case in this application.  An end user in an overseas power plant uses a pneumatic positioner in their steam bypass system.  A pneumatic positioner can best be correlated to a PWM (Pulse Width Modulated) linear actuator.  It will take a supply signal of various forms and provide an output to an actuator or valve, most often to regulate pressure/flow.  So, why not just use a pressure regulator?  Because a pneumatic positoner can be programmed to respond differently to different inputs, and it can function in real time.  Meaning, that when the supply signal reaches a certain threshold the output action can be preset, adding precision to a pneumatically controlled application.  And, as application needs change, the adjustments can be automated.

Some pneumatic positioners are pneumatically controlled (the input signal is a compressed air pressure), but most are electronic.  The end user in this case was using an electrically controlled unit that was experiencing shutdown due to the high ambient temperatures.

When cooling in an application like this it is important to consider the needs (and restrictions) of the application.  To blow ambient air was not an option because of the high ambient temperature, so a Super Air Amplifier, Super Air Knife, or Super Air Nozzle weren’t viable options.  And, the pneumatic positioner was exposed to ambient conditions, with no intent to place within an enclosure.

The lack of an enclosure ruled out a Cabinet Cooler, but a Vortex Tube based solution was still possible.  When considering the heat load and required cooling capacity, the end user determined that with less than 200 BTU/hr. of cooling, the application should run flawlessly. This customer also expressed they may have fluctuations in there pressure supply, and ambient temperatures which would create the need to provide a larger Btu/Hr Vortex Tube in order toake up for lower pressures and increased temperatures. Our smallest Vortex Tube is capable of producing 550 Btu/Hr and was recommended for a successful application.

If you have an application problem in need of compressed air solutions, call an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

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