pressure problems hplc agilent

[elisa]

hi , my problem is that the pressure of my hplc is too high. I already disconnect all parts(but pressure stay too high) , exept those of the quarteray pump system. Very strange is that when I purge I still have a pressure of 25 mbar. Normally it must be 0 mbar. I think the MCGV is the cause of my problem, but I'm not sure.

Has somebody some test suggestion, so that I know where the too high pressure comes from?

thanks!

[DaveM]

How far back did you go when you disconnected all parts?

For instance, did you take the purge valve off and change the filter (the white one about 1cm long)?

If this doesn't help I would guess that there are some particles in the pump somewhere, and you will have to take it apart to clean or replace various parts. Instructions should be with the kit when it was installed. If you think it's the MCGV, change or clean that first.

DM

[Consumer Products Guy]

First replace the frit in the purge valve. Normally over about 8 bar when purging an aqueous phase at 5ml/min means it's time to change that frit. Use the thin 14mm open end wrench after removing the blue outlet tube. Remove the purge valve, pull off the plastic/gold cap with your fingernail, then use a paper clip to spear and then pull out the old frit; note that the slit faces you, install new frit and re-install.

I doubt that the multichannel mixing valve is involved, and that can be bypassed anyway for troubleshooting (or to run RID or conductivity detector).

[elisa]

Thanks, I start with replacing the frit of the purger

[rindtr]

if changing the frit not works, pressure shift could be a sign of occumilation of particles in lines before the pump. washing your lines with warm water with a gentle flow could be the answer.

[danko]

What would be the mechanism behind a potential pressure rise due to accumulation of particles in lines before the pump/s?

Best Regards

[haiedc]

Thanks, I start with replacing the frit of the purger

The clog can be at anywhere, but not before the pump (if yes, the pressure will not rise but fall).
You should check the frit, then the out let ball valve, the capillary, the injection valve and the capillary to the column.

[rindtr]

The clog can be at anywhere, but not before the pump (if yes, the pressure will not rise but fall).
You should check the frit, then the out let ball valve, the capillary, the injection valve and the capillary to the column.[/quote]

yes you are right if there exists a precipitation before the pump it would possibily lowers the pressure, and i agree with you, there is something forcing the pump. may be it could help to disconnect all parts and reconnect them one by one while controlling the pressure.
pump outlet unplugged/pressure high=frit
column inlet unplugged/pressure high = capillary from pump to column column outlet unplugged/pressure high= column is the problem
it goes like this

[Jackus]

What would be the mechanism behind a potential pressure rise due to accumulation of particles in lines before the pump/s?

Best Regards

I think it is a small nonsense...