Problems with the solvent delivery system for a waters 2695

[cwehinger]

Two weeks ago we started to get a “lost sync error (0)”. The company we use for PM looked at the instrument and thought that the error was the pump driver board. We installed a re-furbished pump driver board but the error did not go way. We installed a new pump driver board and the error stopped. I ran it at 1ml per minute with 50:50 methanol:water, for a hour or two and it ran fine. After about 3 hours I stated to see a pressure fluctuation. The fluctuation was about half of the total pressure.

After contacting out PM Company again, he thought that it may be bad pump. We replaced the pump. Again it ran fine for a few hours and then the pressure fluctuation began.

The next suggestion was a new power supply unit. When that was switched out we were not able to make it past the start up of the instrument. We were getting a “plunger homing error (0)”

We tried switching the pump wires to recreate the error on the (1) pump, but the error is always on the (0) pump.


Both of the pumps were replaced on this instrument back on 9-9-2011 with re-built pumps. The error messages and series of error back then are very similar to what we are seeing now.


The instrument is not used heavily, and the methods that we run on it are very vanilla,

I fell like at this point we are just throwing parts at it and hoping for the best.

Does anyone have any suggestions on what the problem could be or how we could continue to trouble shoot it?

Thank you in advance

[Hollow]

just ideas coming up to mind

- pressure fluctuations:
-- check valve issue?
--- is mobile phase online mix or pre-mix?
--- is degasser working well (<=0.6 psia)
--- can you additionally degas by He sparging

-- gradient proportioning valve (GPV) failure
--- test GPV (mixture correctness)

- homing error
-- too much backpressure during initialize
--- blocked in-line filter
--- blocked somewhere else after indicated pump (search forum, something similar exists)
--- faulty pressure sensor?

-> open sparge valve before power on

- synch error
-- not sure if it was this error, but some were about a too old button cell on the mainboard (not only for the EPROMs but also used for some reference voltage)

- "best practice":
if shutdown for some longer period, change every line to Methanol before shutdown (of course, after you've flushed out any buffer with water in advance)

[aceto_81]

plunger homing error indicates that the pump is finding to much backpressure when initializing,
if this is due to the inline filter (most of the time), you can bypass this by opening the purge valve when initializing. (and afterwards replace the inline filter )

The sync error: probably failing pump torpedos, you should replace them entirely. (At least that is what our service engineers do, and afterwards we don't had the error back)


Ace

[cwehinger]

Hi,

We did end up replacing both of the torpedo pumps and now it is running without any problems.

Would anyone know why we would have to replace the pumps twice in two years. I thought that the pumps were very robust and normally would last for a very long time.

Thanks for all your suggestions

Chuck

[LC_labrat]

Is the PM company performing maintenance on the pumps, ie changing the seals/plungers and filters/check valves? From my experience if the maintenance is done yearly and system is flushed appropriately, rarely will a pump need to be replaced. Of the 30+ HPLCs we have I can count on 1 hand the number of pumps that were replaced. It happens but not very often and that's with daily to weekly use of the instruments.

[Hollow]

we had to replace such a piston on our 2695 only once (guess was back in 2005) and never since then.
System is working quite well and is 14 years old now.
Except the annual maintenance with PM Kits, only few service visits needed, maybe 1-2/year.

Did you inform your local Waters rep. about this?

[aceto_81]

I think there were problems with old torpedos (leaking oil), but the newer types are more robust.
Maybe you got old torpedos?
(I think you could see the difference by a black knob on the torpedos, this are the old ones.


Ace

[cwehinger]

Hello

Thanks for all the replies.

aceto_81,
Yes the replacement pumps that we got back in 2011 were the older style and did leak a yellow, lubricant every once in awhile. The PM provider that we were under contract with at the time said that it was normal and we should not be concerned. I am begging to think that they might have given us old torpedoes and or torpedoes that were not refurbished correctly. That company did the refurbishing in house. Our contract was up 3 months later and they tried to increase their price 3 fold so it forced us to switch to a new PM provider.

LC_labrat and Hollow
We do annual PM on the instrument that includes changing all of the seals and plungers, check vales and filters along with the usual injection PM. Besides that the only other maintenance that we conduct on the instruments is flushing the system in-between runs to clear out any buffer that is left, and changing the in line frit if the pressure becomes too high.
We did not contact Waters. The system was bought second hand and we do not have a service contract with them, so they have not been very helpful with issues in the past. Most of their help is suggesting which instrument would be a good replacement for the one that we currently have.

My next question is could a corrupt pump driver board have been responsible for the early death of our pumps? And if not should new pumps from Waters have any difficulty communicating with an original pump driver board?
We originally believed that the pump driver board was causing our problems so we borrowed a new one. It did not solve the problem, but we left it in while we were trouble shooting the rest of the instrument just to be safe. Now with the two new pumps and everything running properly we tried to put the old pump driver board back in, but we are getting a solvent deliver hard ware error. When we put the new pump driver board in the instrument runs fine.

I am just having a tough time believing that we could have had both pumps and the pump driver board all go bad at the same time.

Thanks for your answers in advance


Chuck