Aux EPC or PCM for Collision Gas 7890/7200

No.  There is a QTOF specific collision cell EPC module. The software needs to recognize it.

G3850-60039 | Agilent   EPC module

G3470-60550 | Agilent,  Fitting and 1/16" tubing to go from the EPC module to the QTOF CC 1/16" Swagelok connection.

Is the 7890 setup for the MS transferline heater/sensor connection?  Has that GC ever been run with a mass spec?

Is it a 7200A or 7200B ? What's the serial number?

Is there a way to zero or calibrate the CC gas EPC module? I noticed an offset flow value that seems to affect N2 and He readings. I’ve already attempted to zero the flow using the instructions provided in a previous post 'How to Zero a Flow or Pressure Sensor in EPC Modules', but I haven't had any success. Could anyone provide further guidance on how to resolve this issue or suggest additional troubleshooting steps?

Hi, how big is the offset? If the zeroing didn't work, and the offset is a consistent value, my initial gut reaction is that it sounds like a problem with the epc module. Was it working before and this issue just started or are you setting it up new and having this problem?

Can you try increasing or decreasing the pressure at the regulator on the tank and seeing if the value changes? If it changes with pressure, that would definitely point to an actual hardware issue with the gas block, but if not it's much more likely to be a sensor or software issue.

Thank you for your suggestions!

The offset flow is currently reading around 1.3 mL/min for the quench gas (He) and 1.1 mL/min for the collision gas (N2). Since I’m setting up a pre-owned instrument, I don’t have any detailed information on the previous settings or conditions.

I tried adjusting the pressure on the tank as you recommended, but unfortunately, it didn’t have any noticeable effect on the offset flow.

The normal reset/zeroing doesn't work with the CC EPC module. It's calibrated to be used with the exit in vacuum.  I bet it's fine. This is a low failure rate part.

By default, a 7200 doesn't use any helium in the CC and will show a reading even if there is no helium plumbed to it.

Thank you, Paul! I feel much more at ease now, knowing the CC offset flow is within the normal or expected range. 

How about the required 0.5 ml/min helium flow for the IRM? I'm unable to control such a small flow rate through the CC EPC.

Paul is THE guy if you need to know something so you can definitely take his answers to the bank. As far as the IRM goes though, correct me if I'm wrong Paul but isn't that flow rate ultimately regulated by the needle valve at the actual IRM vial? Here's the schematic of the system plumbing from the troubleshooting manual:

Paul is THE guy if you need to know something so you can definitely take his answers to the bank. As far as the IRM goes though, correct me if I'm wrong Paul but isn't that flow rate ultimately regulated by the needle valve at the actual IRM vial? Here's the schematic of the system plumbing from the troubleshooting manual:

raphasanz  - Will you actually be using IRM?  Very few use it on GC QTOF. The whole IRM setup is very touchy.

US1247H001 was sold as an EI/CI mainframe, so the flow diagram Richard987 shared is correct. That means the CI subsystem flow controller provides the 0.5 ml/min of helium and not the CC EPC module. Make sure that there is never more than 30psi of any gas plumbed to the CI subsystem as higher pressures damage the flow controller. 

The needle valve to the foreline pump sucks away much of the PFET as full headspace vapor out of the vial will overload the system.