Rough pump recommendations for Agilent 5975C MS

[wss]

We had one of our 5975 MSD rough pumps fail recently (an Agilent DS 42 RVP (G3170-80048)) and to keep the instrument going I quickly swapped it out for a Pfeiffer Duo 2.5 from another dormant instrument... which means I'm now down one pump.

Rather than just getting a quote from Agilent for a stock drop-in replacement, I was wondering if anyone has a recommendation for an alternative?

I was considering an oil-free pump or similar if one's available for a justifiable price difference, or if there are non-Pfeiffer, non-Agilent, non-Edwards equivalents that require less maintenance or are more reliable than the standard range of pumps Agilent supplies with their 5975/7s. With 24/7 operation I find I've had to replace the pump seals on a number of our pumps, so if this can be avoided for longer on a new pump it'd be advantageous.

[benhutcherson]

There's nothing wrong with Edwards pumps, or with Agilent(formerly Varian) pumps for that matter.

The problem is that since the 5973, Agilent has been supplying physically small "double speed" pumps that reduce the overall instrument footprint. These pumps have less pumping capacity than the Edwards E2M2 that was supplied with the 5972 and earlier. In addition, their higher rotational speed causes them to run VERY hot(which gives a higher hydrocarbon background, especially in diffusion pump instruments) and tends to give them a shorter service life before a rebuild is needed.

The often recommended replacement is the Edwards RV3, which is similar to but actually a bit better than the old E2M2. You can't plug it into the back of the MS-you will need to plug it directly into the wall-and you'll need to either change the flange on your rough pump hose to KF25 or use a KF16-KF25 adapter.

I like the Varian, now Agilent, DS102, which is essentially identical in specs to the RV3(splitting hairs on the differences, but both have similar pumping capacities and ultimate vacuums).

Both of these pumps run quieter and cooler than the stock pump that came with your mass spec.

Agilent now sells an oil free scroll pump. It's only compatible with turbo pump instruments, and is pricey.

Also, there are companies out there that rebuild pumps, often at a relatively modest cost compared to new. There use to be a company in Louisville, KY that did it-no idea if they're still there. Normally a rebuild kit is ~$200, and a pump shop will charge about the same to do the work. If you're handy you can do it yourself, although the newer pumps are complicated enough that about all I'll brave with them is replacing gaskets if they start leaking. Its worth having your old rebuilt as a spare.

[wss]

There's nothing wrong with Edwards pumps, or with Agilent(formerly Varian) pumps for that matter.

The problem is that since the 5973, Agilent has been supplying physically small "double speed" pumps that reduce the overall instrument footprint. These pumps have less pumping capacity than the Edwards E2M2 that was supplied with the 5972 and earlier. In addition, their higher rotational speed causes them to run VERY hot(which gives a higher hydrocarbon background, especially in diffusion pump instruments) and tends to give them a shorter service life before a rebuild is needed.

The often recommended replacement is the Edwards RV3, which is similar to but actually a bit better than the old E2M2. You can't plug it into the back of the MS-you will need to plug it directly into the wall-and you'll need to either change the flange on your rough pump hose to KF25 or use a KF16-KF25 adapter.

I like the Varian, now Agilent, DS102, which is essentially identical in specs to the RV3(splitting hairs on the differences, but both have similar pumping capacities and ultimate vacuums).

Both of these pumps run quieter and cooler than the stock pump that came with your mass spec.

Agilent now sells an oil free scroll pump. It's only compatible with turbo pump instruments, and is pricey.

Also, there are companies out there that rebuild pumps, often at a relatively modest cost compared to new. There use to be a company in Louisville, KY that did it-no idea if they're still there. Normally a rebuild kit is ~$200, and a pump shop will charge about the same to do the work. If you're handy you can do it yourself, although the newer pumps are complicated enough that about all I'll brave with them is replacing gaskets if they start leaking. Its worth having your old rebuilt as a spare.

Thanks for the info. I should have phrased my query a bit better - agree that there's nothing wrong with Edwards, etc. pumps. in general. Also agree that the stock pumps are undersized - when I was working at my last job (a university), I would end up swapping out the smaller pumps for a RV3s or equivalents and these did perform better, but there was usually a surplus of them that I could scrounge in the department (used on Schlenk manifolds) so it was a no-brainer. I'll need to compare costs of the RV3 vs. E2M2 equivalent, because that's what the decision will hinge on. I use a locally-made pump which is about equivalent to an RV3 on the 5973 I run at home. The instrument this pump will end up on though has a turbo installed.

I've also got this big Agilent unit which was ex-LC-MS which ran very well on the 5975, but it has all this built-in control electronics that would shut it down unexpectedly so I had to go back to one of these small pumps. I'll see if I can find out the model number - it would be good to figure out what the fault on the pump was.

I will see if Agilent sell a rebuild kit for the little pump. I've done a rebuild on an RV3 but only once, and never on one of those little Agilent pumps, but I assume it's straightforward. Time is a bit of a scarce resource at the moment though, so I'll probably be able to justify a new pump and retain the old one for a rainy day (or if we ever hire someone who's handy enough).

[benhutcherson]

AFAIK, the E2M2 is no longer made and the RV3 is its defacto replacement, although in almost every way the RV3 is a better spec pump.

I use to buy rebuild kits from Capitol Vacuum in Chantilly, VA. The last time I bought one was in 2020. Unfortunately, when I went looking back before Christmas, it seems as though they are no longer around or at least not in that business-it's a shame as they had a pretty complete catalog and were very reasonable.

Edwards does sell kits and individual parts for their pumps, but they are pricey. In fact I remember at my last job going round and round with our ordering guy(who liked to spend more time second guessing peoples orders than just trusting the science staff to order the right thing). I'd ordered a major rebuild kit including vanes for an E2M1.5 from CapVac for about $200, and he tried to argue with me that the $150 kit from Edwards(which was just a seal kit) for $150 was the same...

I don't have any great current leads I've actually dealt with on aftermarket rebuilt kit suppliers, but a quick search led me here

https://www.precisionplus.com/Brands/Va ... 700212242I

Remember that Agilent pumps are one of the "pieces" they kept basically intact from the Varian acquisition, and as best as I can tell the rough pumps they sell now are no differnt from their Varian precursors other than having the Agilent name slapped on them. I've spoken often on here of my love of the Varian DS102. At my last job, I ran those pumps a lot. Varian Saturn 2000 ion traps were once a very popular budget GC-MS(I fought with one for years on and off at my last job, and shortly before I left I bothered to learn a bit more about it, kept it in service, and actually really loved it even though it certainly had its quirks). The DS102 was the standard pump supplied with a lot of Varian GC-MSs, including the Saturns and even the big 1200/300 Triple Quads(phenomenal mass specs...) so I always had a bunch around. The one I'm running now actually is Agilent branded, but I still call it a Varian pump

Do you know the model number on the pump from your LC-MS? Between atmospheric pressure ionization and the "intermediate" vac area, LC-MSs often have big backing pumps. The last I did much with was a Finnigan LCQ Duo, and even after I gave up on it(a story for another day...) I kept its Edwards E2M8 pump, a massive 220V job. Depending on what model pump you have, it may be possible to bypass the control electronics.

With all of that said, too, don't discount some strange things happening using a pump that big.I can't tell you where exactly I saw this, but I seem to remember in a 5973 manual seeing that you could trip errors if the foreline pressure fell too low(maybe 5mTorr? Maybe lower than that? I know I've seen 7mTorr on a 5975 with a DS102 and blank ferrule and it was fine). Of course on a turbo instrument I have no idea how the instrument would know it was too low since Agilent, in their infinite wisdom, doesn't see fit to put foreline gauges on turbos. That's actually on my to-do list to see if I can figure out how to do that, although I've had bigger things to worry about.

Of course the other side of that too is that past a certain point, a bigger backing pump won't necessarily decrease pressure. In some cases on diff pump 73s/75s with a blank ferrule(best case scenario for vacuum) I've seen order of magnitude improvements in hi-vac when going from a stock pump to an RV3 class pump(again, check the spec sheets, the DS102 and RV3 are essentially interchangeable). The larger pump does improve vacuums with analytical column flows, and IME with larger pumps you can keep acceptable vac levels with higher column flows than Agilent specs. IIRC I was able to do 2mL/min(helium) in the past with a 5975 diff pump with an RV3 where Agilent says 1.5ml max. That was when someone came to me and just had to run a .530mm column(pretty much the opposite of where I like to go on GC-MS, where I'll run .2 or even .18mm if I can get away with it).

And sorry for my 5:00AM, been awake since 2:00AM with a 1 year old who won't sleep unless I'm holding him, not enough coffee yet rambling.

[James_Ball]

If you search rebuild kits you can find them for pretty much any pump out there. I just got one for an RV5 on my Agilent 7000C that is leaking, just have not had time to install the new seals in it. The motor for RV3 and RV5 are the same so I had already swapped in a new motor when the other one was bad.

I too prefer to upgrade to the larger pumps if I have one available and if I had to order one I would definitely opt for the RV3 sized one on any of the 59xx instruments.

Prices are definitely high for new pumps. Here at work we order the ULVAC pumps that are oil based but have a magnetic coupler between motor and pump so there is no seal to leak. For the most part they have worked well for us and they are less expensive.

[cjm]

We're also using the ULVAC pumps with good success, although none have run for more than 2-3 years. They're so much quieter than any other pump we have.