Hi Alex,
Disclaimer: This is just my opinion based on my experience with Prodigy probes
and vacuum systems in mass spectrometers, and should not be construed as advice.
I am in no way telling you what you should do with your instruments. Also,
you are far less likely to get in trouble for following Bruker's recommendations
than for going against them.
I use information from the Prodigy Service GUI to decide when to service my
cryoplatforms. It's accessible from the the Configuration tab of Prodigy
Display (Topspin -> Manage -> Spectrometer -> Prodigy Display).
Transfer line:
If the nitrogen hold time is 10 days, the line is fine, if it's less than seven,
the line definitely needs pumping. For a more quantitative answer, I look at
Analog Sensor Inputs -> LN2 Dewar Pressure: The plot has a sawtooth pattern that
starts low after nitrogen fills and rises fairly linearly as the dewar empties.
If the initial pressures after the fills are comparable to older values from
when the probe was installed, the transfer line is fine. My initial pressures
with a freshly pumped transfer line are in the 25 to 30 mbar range, and the
values creep up over time, getting into the 50's after 2 years. It would be
great if someone from Bruker could respond to this with official ranges for
acceptable minimum and maximum dewar pressures.
I pump the line if needed using the Prodigy cryoplatform when the probe is
warm. There is a Pump Transferline Vacuum button in the Status tab of the
service GUI that gives step-by-step instructions.
Roughing pump:
Analog Sensor Inputs -> Partial Load Vacuum: The value should be near ambient
(~1000 mBar) most of the time with sharp dips every couple of days. If the
dips bottom out in the low single digits, the roughing pump is fine. If the
dips are more frequent than every couple of days, there is a vacuum leak. If
the roughing pump is running constantly, there is a major vacuum leak that
needs to be addressed ASAP. The Duty Counters folder shows the total roughing
pump hours as of the date and time shown in the upper right corner of the GUI.
This should be in the few 100 hours/year range unless there is/was a vacuum leak
or the probe is warmed often, since the roughing pump should only run for an
`hour every couple of days when the probe is cold. IIRC the diaphragms are rated
at 20k+ hours, so they should outlast the instrument at the rate the pump normally
runs. Bruker replaces them at the service call, likely because the diaphragms are
cheap so they might as well while they are there.
Turbopump:
Turbo Pump -> Tp current and Tp bearing temp: You should see a sawtooth pattern
with a few-day period. The transitions from high to low correspond to the roughing
pump turning on. If the values are unchanged from old/installation values the turbo
is fine for now. If there is no vacuum leak but the minima of current and temp are
starting to climb, the turbo needs to be serviced or replaced soon.
The Tp Operating Hours shows the total hours as of the date and time in the
upper right corner. My Prodigies use Pfeiffer HiPace 80 pumps, which have
4-year maintenance intervals according to Pfeiffer, so that's what I go by.
To summarize, I feel comfortable delaying service if the nitrogen hold time
is more than 7 days, the partial load vacuum gets down to low single digits,
and the TP current and bearing temps are normal; and I pump my own transfer
line if that is the only issue with the system.
Let me know if you have any questions or corrections,
Ivan
PS. Here is my understanding of the vacuum system in the Prodigy, in the hope
that some of you might find it useful:
[Probe, S3 CRP Vacuum] {"V6 Operator" valve} [Rigid vacuum line, low pressure
side of turbo, S12 Penning vacuum (not in older systems)] [high pressureside
of Turbo] {"V14 Partial Load" Valve} [low P side of roughing pump, S7 Partial
load Vacuum] [roughing pump exhaust, ambient
During normal operation the Operator is always open. The Partial Load valve
(PLV) and the roughing pump (RP) cycle between closed/off and open/on to
maintain a reasonable pressure on the high (output) side of the turbo, which
results in the sawtooth pattern in the TP current and bearing temp. A leak
in the low side of the turbo results in quicker pressure rise on the high
side with the PLV closed and therefore shorter partial load cycles.
The CRP vacuum measures vacuum inside the probe. The value at operating vacuum
appears to be probe dependent and drift over time (years) but has been in the
500-560 mV range for my probes. Readings at ambient pressure have been
in the 200 to 300 mV range.
S12 Penning vacuum seems to be used only during cooldown and for troubleshooting
and isn't installed on my older system. It measures the vacuum on the low side
of the turbo pump, which includes the probe when the operator valve is open and
just the vacuum hose when the operator is closed.
S7 Partial Load Vacuum: measures the vacuum between the Partial Load valve
and the roughing pump. When PLV/RP are open/on this measures the high side
of the turbo. With PLV/RP closed/off this is the ambient pressure in the
enclosure.
--
Ivan Keresztes, Ph.D.
Director, NMR Facility
Department of Chemistry and Chemical Biology, Cornell University Baker Laboratory, Ithaca, NY 14853.
phone: (607) 255 0709, fax: (607) 255 4137, email: ik54_at_cornell.edu
(he/him/his)
nmr.chem.cornell.edu
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#2140): https://urldefense.com/v3/__https://ammrl.groups=
.io/g/main/message/2140__;!!PvDODwlR4mBZyAb0!UVeum1WLKC60VoADm5A1WTkOCpzU8b=
DAcNWuDyYR_0AXj-701E0iy_vIarN4rDIBKBTQ0dbzRJVOutAnqk66IncKtTVq$
Mute This Topic: https://urldefense.com/v3/__https://groups.io/mt/111535011=
/7559972__;!!PvDODwlR4mBZyAb0!UVeum1WLKC60VoADm5A1WTkOCpzU8bDAcNWuDyYR_0AXj=
-701E0iy_vIarN4rDIBKBTQ0dbzRJVOutAnqk66InPKQYka$
Group Owner: main+owner_at_ammrl.groups.io
-=-=-=-=-=-=-=-=-=-=-=-
Received on Sat Mar 08 2025 - 09:22:01 MST