Chromatography Forum

Oven shuts off while warming up. The flappers in the rear don't quite close all the way. Interestingly, if instead of warming up at 90C I immediately set it to 300C, the flappers shut all the way; I can then set the oven temp at 90C as it's passing through ~85C, and it functions as should. GC runs normally, ramps back down, accepts another run, etc. with no oven warning.

Are these signs of an incipient flapper motor failure? Or is there some maintenance I can do to rectify the situation?

What you describe is how flapper-motor failures have presented themselves to me when they've occurred. Replacement of that motor is not a difficult repair. I've only had a couple of those failures in almost 30 years of doing this stuff.

Interesting that you can get to 300 at all. I don't remember mine ever letting me go that high once the flapper motor started to fail.

rb6banjo wrote:
What you describe is how flapper-motor failures have presented themselves to me when they've occurred. Replacement of that motor is not a difficult repair. I've only had a couple of those failures in almost 30 years of doing this stuff.

Same here; not a difficult in-house repair. Once I had to rivet a flapper back onto its support. I think I did about 2 of these electric motor assemblies on 6890s, and at least one on the 5890s, they are different.

I stocked a spare electric motor for each series, were different.

In my last few years, my pointy-haired boss likely would've called in Agilent Service, as he'd be terrified that this would compromise cGMP validations because I didn't have a certificate on file stating that I "was qualified". So good to be retired and away from him. In my career, there were a few things that I showed service engineers what to do !!! I was still allowed to "point".

Consumer Products Guy wrote:

rb6banjo wrote:
What you describe is how flapper-motor failures have presented themselves to me when they've occurred. Replacement of that motor is not a difficult repair. I've only had a couple of those failures in almost 30 years of doing this stuff.

Same here; not a difficult in-house repair. Once I had to rivet a flapper back onto its support. I think I did about 2 of these electric motor assemblies on 6890s, and at least one on the 5890s, they are different.

I stocked a spare electric motor for each series, were different.

In my last few years, my pointy-haired boss likely would've called in Agilent Service, as he'd be terrified that this would compromise cGMP validations because I didn't have a certificate on file stating that I "was qualified". So good to be retired and away from him. In my career, there were a few things that I showed service engineers what to do !!! I was still allowed to "point".

Same here with showing the engineers what to do to fix things

I have had flapper motors do this on 6890s and sometimes a simple reboot by shutting down the power for a few seconds and turning it back on will re-zero the flapper position. If it occurs often though, the motor is losing its position and probably need to be replaced.