Chromatography Forum

Hello,

I have an Agilent 6890N and from a month ago I have this message" Shutdown 5 - back inlet pressure shutdown" I've checked for leaks, I cleaned the inlet tubing, I replaced the chemical trap, I set the flow and pressure sensors to zero and nothing works for good. I mean, when the error appears and I try all that I mentioned before and then It works but for a few days, then I have the same problem. I dont know what can I do?

thanks

Are you sure your inlet pressure (tank pressure ) are ok?....30psi higher
For example, if your maximum pressure in your run is 25psi, your inlet pressure from tank must be at 60psi minimum
Maybe, you have a leak when oven program is running???.

Hi,

yes I checked the Helium supply and I have enough quantity. I don't think I have a leak due to I already checked every connection and everything looks ok.

what is the helium tank pressure and what is the helium pressure at the exit of this tank?

Hi Diana
Try this:
http://www.chem.agilent.com/Library/Sup ... a15718.pdf

Hi!

thanks for the document, I tried that and everything worked fine I also check for leaks with an electronic detector and I don't have leaks. After that the instrument worked perfect for about 2 months but today the same error appeared and I don't know what can I do.

thanks

Is this inlet working as split or splitless ?

If split, what is split ratio, column flow, pressure ?

Hi!

splitless, column flow 1mL/min and pressure 83 kPa

In split mode increasing split ratio helps pressure to achieve set value.

It's not the case here, you work in splitless mode.

Just a long shot, but is your helium cylinder valve completely open? If not, the diaphram could shut down periodiacally (as if someone shut down the tank).

What is the flow through the inlet when it is in splitless mode ?. Do you have flow out of the split vent when the inlet is below set pressure ?

Peter

the helium botle is almost full and the valve is completely open.

The flow through the inlet in splitless mode is 1 ml/min, I haven't checked if I have flow out of the split vent when the error appears, today the instrument has worked without any problem so next time when the inlet is below set pressure Im gonna check.

thanks for your help!

Hi Diana

while it is working well, measure the split flow and the septum purge flow anyway - it will be a useful comparison. The flow into the column is 1 ml/min, the total flow through the inlet is this plus septum purge plus split flow. What is the total flow set at in the software method ?

Peter