Hewlett Packard 5890 EPC Board, Refurbished
The 5890 Split/Splitless Epc Inlet system uses pressure to control flow through opentubular, capillary columns. The capillary column flow is not measured directly, but iscalculated from the column dimensions, inlet and exit pressures, temperature of thecolumn, and carrier gas type.The 5890 Split/Splitless Epc inlet is a backpressure regulated system. This simplymeans that the control and feedback of the pressure comes from “back” or “upstreamfrom” the controlling valve. If the upstream pressure momentarily drops below setpoint,a feedback signal causes the control valve to close more until the pressure rises abovethe setpoint, after which it will open further. The split flow rate and column flow rateare set independently of each other allowing changes in the split flow and column headpressure with changing the total flow.The Capillary Inlet system can be run in two modes of operation—Split and Splitless.The inlet can equilibrate to pressure setpoint if the following conditions are met:The capillary inlet system is assembled correctly and is leak free.
- The EPC control board is configured correctly and all components are functioning.
- There is sufficient carrier supply pressure applied to the GC and the Mass flowcontroller is turned on.(80-120 psi for the standard capillary EPC system yielding at least 60 ml/min of totalflow.)
- The capillary column is installed and configured correctly.
Prior to troubleshooting a problem with the flow system of the GC it is prudent to checkfirst the EPC control board configuration and the Zero on the EPC Channel.NOTE: The EPC board is located on the right hand side of the GC within themain panel and it is plugged into the mainboard of the GC. If at this point you areunsure about how to check these switch settings, please call Agilent. DO NOTPROCEED.The switch settings for the 5890 Series II EPC:IN A1 OR IN B1 Right, currently unused PIDIN A0 OR IN B0 Left, Programmable Cool On Column (PID)/ Right, Purged PackedInlet/ Right, (BPR) Split/Splitless Capillary InletMODE A OR MODE B Left, (FPR) Programmable Cool On Column Inlet & PurgedPacked Inlet /Right, (BPR) Split/Splitless Capillary InletPID= Proportional/ Integral/ Differential heated zoneFPR= Forware Pressure Regulating modeBPR= Back Pressure Regulating modeZeroing the EPC channel is necessary to correct for tolerances of the sensor and otherelectronic components. Zeroing the channel nullifies any offset that would keep a “0”setpoint from being achieved. An improperly zeroed channel will have an actualpressure that is different from the setpoint value, and flow rates will be calculatedincorrectly.Zeroing the 5890 EPC Inlet