E2M1.5 with 5973 Flange Centering Ring

[benhutcherson]

I know I've been rather critical on here of the E2M1.5, but I'm in a situation now where I'm trying to get a 5973 up and going, and an E2M1.5 is my only option for now.

The transfer line from the mass spec has a KF-16 flange, as is the case on all the 5973 and up MSs I've seen.

I guess I hadn't looked that closely at the E2M1.5 before, but it seems that even though the outside diameter of the flange is the same as a KF-16 flange, it doesn't look like it will work with a standard centering ring. Specifically, the recessed area looks significantly smaller.

This is the only major part I'm missing from this unit, and really all I need(I suspect) to get it up and going. Before I either order a KF-16 ring or bum one off a friend who I know will have one, do I need to hunt down anything special to work with this pump?

(this one also seems to have the oil leak that all of these develop after a few years, but I'm hoping I can patch it together by changing the cork seal between the pump body and the motor-this has worked for me in the past)

[benhutcherson]

Okay, never mind-looks like I spoke too soon and it's NW-10...

[James_Ball]

Okay, never mind-looks like I spoke too soon and it's NW-10...

Yup they are smaller. Not sure if I would have any left that size laying around anymore. Someone went though a while back and threw out all my hoarded junk lol.

[benhutcherson]

Did manage to find one on Ebay.

There again, I REALLY don't like this pump, but it's what I have now.

Apparently at the end of the fiscal year we can request "big" purchases. Assuming I can get things working, I'm going to at least try to get an RV3 or preferably a DS102(again, my favorite pump). Depending on how much I can stretch things, I may try to get a G1512A(I have everything else needed for an AS to work with that) or if I get really ambitious try to get an SC3(ethernet) and the ethernet module for the 6890. We'll see what happens-I might have to spread this out over a few years as with ethernet I'd like to upgrade to E.02.02...

[LALman]

I've had pretty good luck getting vacuum fittings from SISweb. Ideal Vacuum and Capitol Vacuum are two others I used when I need rebuild kits.

I've been wondering ever since one of you mentioned putting the backing pump in the other room. There must be some distance from the diff/turbo pump that is too far no matter what sort of backing pump you use. My guess is that its not how much a big pump can transfer, so much as how big a bite it takes at the inlet for each revolution of the pump. A small capacity pump like the E2M1.5 pump even turning very fast is just taking little sips but a hig capacity pump is taking big gulps.

[LALman]

Did manage to find one on Ebay.

There again, I REALLY don't like this pump, but it's what I have now.

Apparently at the end of the fiscal year we can request "big" purchases. Assuming I can get things working, I'm going to at least try to get an RV3 or preferably a DS102(again, my favorite pump). Depending on how much I can stretch things, I may try to get a G1512A(I have everything else needed for an AS to work with that) or if I get really ambitious try to get an SC3(ethernet) and the ethernet module for the 6890. We'll see what happens-I might have to spread this out over a few years as with ethernet I'd like to upgrade to E.02.02...

I just did some pump down trials on my 5971 comparing the E2M2 to the E2M1.5. Just plugging off the pump with a vacuum sensor attached; here are some numbers. Maybe I did a poor rebuild but the E2M1.5 took well over a minute to reach 7 mTorr. The E2M2 reached 10 mTorr in 27 seconds and 5 mTorr in 60 sec. Ultimate vacuum for the E2M2 is 2.7 - 3.5 mTorr. I think the green rubber stopper I stuffed in the foreline fitting was leaking around the edges.

Also, the E2M2 got my plugged off 5971 down to 4.3 mTorr overnight.

[James_Ball]

When I was running the 5971 with E2M2 and a jet separator on the inlet I would normally run in the very low 10^-6 pressures and capped off it would drop into the 10^-7s with no problem.

With direct column fitting and 1ml/min normally it was low 10^-5 range. I got used to seeing those numbers on it and even the 5973s which were sometimes near 7x10^-6 on a good day, then I got the 7000C QQQ and at 1ml/minute I was at 7x10^-7 pressures. Oh how I wish I could get that on a 5973 and see what it would be capable of sensitivity wise

[benhutcherson]

then I got the 7000C QQQ and at 1ml/minute I was at 7x10^-7 pressures. Oh how I wish I could get that on a 5973 and see what it would be capable of sensitivity wise

The only QQQ I've spent any appreciable time with is the Varian 300, but the vac levels on it blew me away. Low 10^-7 was typical for me at 1mL/min.

Granted it would drop to 10^-5 doing both CI and CID, but that's also a lot of extra gas pumping into the vac manifold. Varian doesn't let you set those in terms of flow rates, but rather you set the pressures obtained in the source and CC region. Typical CID pressure was 1.5mTorr, and I think CI with methane was about the same. Doing one or the other, I'd see manifold pressures in the mid 10^-6 range.

The first QQQ I saw, albeit non-operational, was a giant Sciex ESI/APCI unit that was at my undergrad college(and high hopes that never materialized of getting it running). It used a cryopump with liquid helium, which I've yet to see on any other mass spec install. We also had a Finnigan either 700 or 7000(EI and CI sources, but had come from P&G set up for SFC), and I'm pretty sure it had one or two nice sized turbos on it.

[LALman]

When I was running the 5971 with E2M2 and a jet separator on the inlet I would normally run in the very low 10^-6 pressures and capped off it would drop into the 10^-7s with no problem.

With direct column fitting and 1ml/min normally it was low 10^-5 range. I got used to seeing those numbers on it and even the 5973s which were sometimes near 7x10^-6 on a good day, then I got the 7000C QQQ and at 1ml/minute I was at 7x10^-7 pressures. Oh how I wish I could get that on a 5973 and see what it would be capable of sensitivity wise

This is just amazing! I am lucky to have my 5971/5972 at 3.0E-5 Torr at 0.5 mL/min and 7.2E-5 Torr at 1 mL/min on He. I must have a vacuum problem. As to the 5973, I agree. At 1 mL/min and a standard turbo the best I can get is 3.0E-5 Torr.

[benhutcherson]

5971/2 backed by a Varian DS102, I would routinely get high 10^-6 at .5mL/min rest and ~2.5x10^-5 at 1mL/min. Blank ferrules would get me mid-10^-6 range.

Of course if it had been off any period of time, it took a couple of days of pumping to get there.

[James_Ball]

When I was running the 5971 with E2M2 and a jet separator on the inlet I would normally run in the very low 10^-6 pressures and capped off it would drop into the 10^-7s with no problem.

With direct column fitting and 1ml/min normally it was low 10^-5 range. I got used to seeing those numbers on it and even the 5973s which were sometimes near 7x10^-6 on a good day, then I got the 7000C QQQ and at 1ml/minute I was at 7x10^-7 pressures. Oh how I wish I could get that on a 5973 and see what it would be capable of sensitivity wise

This is just amazing! I am lucky to have my 5971/5972 at 3.0E-5 Torr at 0.5 mL/min and 7.2E-5 Torr at 1 mL/min on He. I must have a vacuum problem. As to the 5973, I agree. At 1 mL/min and a standard turbo the best I can get is 3.0E-5 Torr.

One question would be how accurate is the 1ml/min flow rate. If any column has been trimmed off it will get faster unless you reduce the head pressure and it has to be calculated to know exactly how much it is flowing. 1ml/min verses 1.2ml/min could make the difference in the pressure readings.

[benhutcherson]

When I was running the 5971 with E2M2 and a jet separator on the inlet I would normally run in the very low 10^-6 pressures and capped off it would drop into the 10^-7s with no problem.

With direct column fitting and 1ml/min normally it was low 10^-5 range. I got used to seeing those numbers on it and even the 5973s which were sometimes near 7x10^-6 on a good day, then I got the 7000C QQQ and at 1ml/minute I was at 7x10^-7 pressures. Oh how I wish I could get that on a 5973 and see what it would be capable of sensitivity wise

This is just amazing! I am lucky to have my 5971/5972 at 3.0E-5 Torr at 0.5 mL/min and 7.2E-5 Torr at 1 mL/min on He. I must have a vacuum problem. As to the 5973, I agree. At 1 mL/min and a standard turbo the best I can get is 3.0E-5 Torr.

One question would be how accurate is the 1ml/min flow rate. If any column has been trimmed off it will get faster unless you reduce the head pressure and it has to be calculated to know exactly how much it is flowing. 1ml/min verses 1.2ml/min could make the difference in the pressure readings.

Along those same lines, 5890s could be had with either manual pneumatics or EPCs.

The EPC isn't the greatest, but works.

Of course as I'm sure we all know, viscosity increases with temperature, so if dealing with constant pressure as from manual pneumatics, it will only be correct at one temp.

There is a round-a-bout way to find column length as long as its decently close to the nominal value. You can inject a non retained compound(I usually use butane from a lighter) and see its retention time. Assuming your linear velocity is at least in the ballpark, you can then get a decent idea of actual column length. If you really want to be accurate on it(or you find that the column is way off its nominal tagged value) you can go through a couple of iterations of this. I found it close enough when say a .25mmx30m column was actually more like 28m.

[James_Ball]

Do you remember at what point the EPC was capable of doing constant flow?

I can't remember if the first ones only did constant pressure or not.

[LALman]

I've done the timing using an air peak. My well used DB-VRX is only 19m long.

[benhutcherson]

Do you remember at what point the EPC was capable of doing constant flow?

I can't remember if the first ones only did constant pressure or not.

Not sure exactly on that.

At U of L, I had two 5890s sitting next to each other. One was an FID/NPD with manual pneumatics, and the other fed the 5971/2 and had an EPC. I know I could do constant flow on that one, even though it was a bit fiddly compared to newer EPCs. It still had a manual knob I think for septum purge(don't hold me to that) that you had to set with a flow meter. I know that I had to mess with that to get the head pressure down for resting flow, and I think when I raised the flow again I'd have to increase it(which meant setting septum purge daily).

If it's of any relevance, the 5971 on that dated to 1990.

Where I am now, we have a 5890+ with a pair of EPC packed column inlets. I haven't played with those yet.