Chromatography Forum

If you were doing environmental work and were offered a 5973 ms, would you choose a turbo pump or a diffusion pump option and why?

It would depend on if my environmental analysis were going to be the same for the next ten years. If all it had to do were VOA's I would chose the diff stack because it will not fly apart or seize any bearings. If I had to choose between semivoa and voa and swap columns to move back and forth I would be more tempted by the turbo with an eye to the potential future failure (expensive) of the the pump. This is because a turbo will pump down more quickly. The other thing I would think about is a no-vent option and staying with the diffusion pump option.

I have had very good luck with the diff. stack if you pay attention to a few key things like flow rates.

Best regards.

If you're doing "normal" GCMS with standard applications I would always prefer the diff pump although everybody else will say the turbo pump is more up to date.
A diff pump is very very rough and doesn't need much service. Even the yearly recommended oil change can be skipped if you have your system under control and have a look at the oil when doing some service on the GCMS system.
If a turbo pump isn't neccesary because of pump down speed or special application issues (high flow rates e. g.) a diff pump is the cheapest and most confidental thing.
We operate a 5973N with a 6890 since 10 years and NEVER had ANY problem with the diff pump or the pre pump (Edvards). Two other devices with a Pfeiffer turbo pump get broken almost every two years (each time about 7000 Euro per pump) - just a short time after warranty period is over...!

My vote is a turbo. I have limited experience with diff pumps but that experience was not plesant. We had an early HP 5995 that backstreamed every time there was a power glitch. We also had a 5988 with two huge diff pumps.

We have 4 5973's the oldest dates from 1999, and have never lost a turbo. The only turbo lost was on a 5970 faairly early in it's life span. It was replaced with a Varian turbo with ceramic bearings and ran fine for years. When we retired it the pump was doing just fine.

just my $0.02.