Pfeiffer Duo 2.5 Question

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Dan Knapp
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Re: Pfeiffer Duo 2.5 Question

Post by Dan Knapp » Wed Dec 20, 2017 3:37 am

I have a Duo 2.5 that overheats and trips the motor thermal cutoff after about an hour of running (Baldor motor). I’ve tried the obvious of replacing the capacitors, but this did not cure the problem. It appears that the pump is putting an abnormal load on the motor. has anyone else encountered this problem with a Duo 2.5?

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Re: Pfeiffer Duo 2.5 Question

Post by ian_krase » Wed Dec 20, 2017 3:56 am


Have you tried measuring the current draw? And compare?

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Samuel Berman
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Re: Pfeiffer Duo 2.5 Question

Post by Samuel Berman » Thu Dec 21, 2017 5:39 am


Yes, even with the exhaust open the pump will still stall out when the 3rd port is closed. I also noticed that most of the oil vapor comes out of this 3rd port rather than the exhaust. For now, I am just leaving this port open with some cloth covering it to stop the oil mist. I'm starting to think that this may be the main exhaust port, but it's very confusing since air comes out of both this and the actual exhaust port. The port does appear to lead to the oil reservoir.
Samuel Berman

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Dennis P Brown
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Re: Pfeiffer Duo 2.5 Question

Post by Dennis P Brown » Thu Dec 21, 2017 11:20 am

Not unlike your pump, my small pump has a second port - it too has to be vented (via std 1/4 in steel tubing) and stay's open - it is used (the pump) to draw off CO2 from foams and as such, could experience sudden large releases of CO2 gas - so I assumed it was an over pressure dump vent (but not sealed with a pressure valve.) The main exhaust port has an anti-vapor attachment device. So, while this pump has two exhaust points, only one is designed as a true exhaust connection port.

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