0230 Cool On-Column Inlet
Contents
1. 2 Wait 10 minutes for pressure equilibration The gauge on the front panel should be stable 3 After 10 minutes shut off the column head pressure by turning the pressure controller full counter clockwise Pressure gauge p Pressure regulator Figure 230 9 Inlet manifold 4 Monitor the pressure gauge for 5 minutes If there is less than 0 5 psi pressure loss approximately 0 1 psi min consider the system leak tight e Ifpressure loss is much greater than 0 5 psi there is a leak that must be found and corrected See Correcting leaks later in this section 5 When the system is considered leak tight the caps may be removed the column reinstalled and the desired pressure set 14 of 20 Inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Column Inlet 230 Leak testing EPC and manual inlets Leak testing the EPC module only Occasionally to track down small leaks you will need to isolate the EPC module from the inlet weldment and leak test the EPC module separately 1 On the keyboard turn off pressure to the inlet being tested Press Front Inlet or Back Inlet scroll to the Pressure field and press Off 2 Use a Torx T 10 screwdriver to remove the screw in the plumbing block on the front of the module Remove the plumbing block from the EPC module being careful not to lose the O rings between the block and the module 3 Replace the inlet s plumbing block with the leak2. 1 Remove the plastic detector cover and the plastic pneumatics cover 2 Remove the metal RFI shield and the rear top cover on the back of the GC 3 Disconnect the ribbon cable for the manifold from the EPC board You may have to remove the adjacent ribbon cable also 8 of 20 Inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Column Inlet 230 Replacement procedures Figure 230 6 Removing the EPC flow manifold 4 Remove the 1 8 inch Swagelok fitting for the gas supply 5 Remove the plumbing block from the front of the manifold one Torx T 10 screw 6 Remove the long screw Torx T 20 from the top of the manifold and slide the manifold out of the back of the GC 7 Reinstallation is the reverse of removal Replacing the supply fitting on a Type 1 EPC flow manifold See Split Splitless Inlet for the detailed procedure Jun 2001 inlets 9 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Leak testing EPC and manual inlets Leak testing EPC and manual inlets Preparation 1 Cool the column to ambient 2 Remove the column from the inlet fitting on the inside of the oven 3 Ifthe quality of the septum is unknown replace it now Septum retainer Septum Spring Insert Figure 230 7 Location of septum 4 Cap the septum purge vent and the inlet s column fitting Use solid no hole Vespel type ferrules 1 8 inch part no 0100 1372 and
3. tray bracket if installed and the left side cover Unclip the heater sensor leads from the connector to the left of the inlet carrier Disconnect the inlet plumbing and reroute the plumbing from underneath the tabs on the left side of the instrument EPC inlets The inlet plumbing terminates in a pneumatics block connected to the EPC flow manifold with one Torx T 10 screw Non EPC inlets The inlet plumbing is located in the manual inlet side carrier The tubing labelled C is connected to the Forward Pressure Regulator The line labelled P is connected to the septum purge regulator 4 of 20 Inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Column Inlet 230 Replacement procedures Figure 230 3 Disconnecting the inlet plumbing block EPC inlets 5 UseaTorxT 20 screwdriver to loosen the three captive screws that attach the inlet weldment to the top of the inlet carrier Jun 2001 inlets 5 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Replacement procedures Heater sensor assembly Captive screw Insulation Figure 230 4 Removing the inlet from the top of the GC 6 Slide the inlet up out of the inlet carrier If necessary you can also slide the insulation sleeve off of the bottom of the inlet 7 Reinstallation is the reverse of removal 6 of 20 Inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Colu
4. 1 16 inch part no 5181 7458 with a 1 8 inch Swagelok nut part no 5180 4103 and a capillary column nut Note As alternate capping devices a 1 8 inch Swagelok cap can be used for the septum purge vent and a capillary column nut with a solid piece of wire the size of a paper clip and a 0 5 mm ID graphite ferrule may be used for the inlet column fitting 10 of 20 Inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Column Inlet 230 Leak testing EPC and manual inlets Manual Figure 230 8 Capping the bottom of the inlet and septum purge vent Note Make sure that the carrier gas source pressure is at least 35 psi Carrier source pressure should always be at least 10 psi greater than the desired inlet pressure Jun 2001 miei 11 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Leak testing EPC and manual inlets Performing the leak test EPC inlets Note Be sure that the preparation steps on pages 10 and 11 are complete before proceeding with this test 1 Set the inlet pressure to 25 psi on the keypad Press Front Inlet or Back Inlet Move to the Pressure field and enter 25 FRONT INLET coc Mode Track oven Temp 150 150 LPressure 25 0 2 Wait approximately 15 seconds for equilibration If pressure cannot be achieved either a very large leak is present in the system or the supply pressure is not high enough 3 T
5. 230 Cool On Column Inlet Programmable Cool On Column PCOC inlets are designed to allow the injection syringe to deposit the liquid sample directly into the capillary column This is accomplished by the use of an insert which serves to align the syringe with the capillary column and the syringe needle Theory of operation At injection liquid sample is introduced directly into the column For manual injections a duckbill valve isolation valve uses inlet pressure to create a pneumatic seal around the needle For automatic injections the duckbill valve is replaced with a septum and nut and the septum maintains the pressure seal For both manual and EPC inlets the flow paths are the same the flow is divided into two streams The carrier gas enters the inlet and flows into the column and additionally provides for a constant septum purge flow regardless of the column flow rate you use Jun 2001 Inlets 1 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Theory of operation EPC inlet An EPC controlled PCOC inlet is a forward pressure regulated system that provides flow to the column A pressure sensor is located just ahead of the inlet and with the proportional valve forms a closed loop electronically controlled system In addition a flow limiting frit 750 mL min at 50 psi is located at the pneumatics entrance A septum purge regulator SPR maintains septum purge flow between 7 and 1
6. 5 mL min Flow Se HOY l ptum purge limiting Proportional Pressure Septum holder regulator not frit valve sensor adjustable spr E Purge Vent Flow 15 mL min Spring and alignment insert Inlet pressure control loop EAR o Detector Figure 230 1 EPC control 2 of 20 Inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Column Inlet 230 Theory of operation Manually controlled inlet The manually controlled PCOC inlet has a forward pressure regulator FPR that controls the column flow rate In addition a forward pressure regulator with a fixed restrictor SPR is used to provide a nominal septum purge flow rate of 15 0 mL min The sample is deposited directly into a capillary column for analysis Forward pressure Septum purge regulator Septum holder regulator as SPR m Purge Vent Flow Spring and alignment insert To Detector Figure 230 2 Manual control Jun 2001 inlets 3 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Replacement procedures Replacement procedures WARNING Turn off the oven and turn off the inlet you are replacing and let them cool down Turn off the carrier gas supply pressure then turn off the main power switch and unplug the power cord Replacing the inlet From inside the oven remove the column from the inlet fitting From the top of the 6890 GC remove the blue inlet carrier cover or the
7. h valve Septum purge cap Inlet fitting Jun 2001 inlets 19 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Leak testing EPC and manual inlets 20 of 20 Inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual
8. mn Inlet 230 Replacement procedures Replacing the heater sensor assembly WARNING Turn off the oven and turn off the inlet you are working on and let them cool down Turn off the carrier gas supply pressure then turn off the main power switch and unplug the power cord 1 If necessary remove the septum nut cooling tower and or needle guide to provide access to the two screws in the top of the cooling fin Note If desired you can remove the entire inlet for better access Cooling fin Heater sensor assembly Figure 230 5 Removing the heater sensor assembly from the top of the GC 2 Remove the two Torx T 20 screws securing the cooling fin to the inlet weldment and remove the fin Jun 2001 inlets 7 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Replacement procedures WARNING 3 Lift the heater sensor leads out of the weldment channel and lift the assembly out of the inlet 4 Installthe new heater sensor assembly and reassemble the inlet You may need to use tweezers to seat the cable back in the channel and fully seat the heater sensor in the weldment Replacing the inlet EPC flow manifold Turn off the oven and turn off the inlet you are replacing and let them cool down Turn off the carrier gas supply pressure then turn off the main power switch and unplug the power cord All EPC inlets and the ECD detector in the 6890 GC use Type 1 flow manifolds
9. module on the lab bench 10 If the leaky component is serviceable such as vent inlet fittings see the following diagram of serviceable parts Figure 230 11 replace them Otherwise replace the EPC module Jun 2001 inlets 17 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Leak testing EPC and manual inlets Caution Aluminum bracket removed for clarity DO NOT completely remove the bracket during valve replacement Aluminum bracket O rings s O ring Septum purge fitting Figure 230 11 EPC module serviceable parts Correcting leaks 1 Use an electronic leak detector to check all areas of the inlet that are potential sources of a leak 2 Tighten loose connections to correct leaks if necessary You may need to repeat the leak test 3 Ifthe pressure drop is now 0 5 psi or less you can consider the inlet system leak free If the pressure drops faster than the acceptable rate continue to search for leaks and repeat the pressure test 18 of 20 Inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Column Inlet 230 Leak testing EPC and manual inlets Potential leak points Check the following areas when checking an inlet system for leaks In the oven Make sure the bottom of the inlet is correctly capped On the inlet Septum At EPC module Three O rings behind block where pneumatic lines enter module Two O rings for eac
10. ocating leaks If the EPC module appears to have a leak you can remove it to locate the leaky component The leak test kit part no G1530 60960 contains a longer ribbon cable to allow you to lay the EPC module on the benchtop for testing Caution Be sure to wear an ESD strap grounded to the 6890 GC chassis while performing this procedure 1 Turn off the main power switch 2 Disconnect the carrier supply tubing on the inlet fitting 3 Remove the top plastic pneumatics cover and the detector cover 4 Remove the RFI shield and the top rear cover on the GC 5 Disconnect the ribbon cable for the module from the main EPC board You may have to remove the adjacent ribbon cable also 6 Use a Torx T 20 screwdriver to remove the screw from the top of the module and slide the module out of the back of the GC 7 Connect one end of the leak test ribbon cable G1530 61370 to the ribbon cable connector on the EPC module and connect the other end to the appropriate connector on the EPC board 8 Reconnect the carrier supply fitting and set pressures as used in the leak test 9 Lay the EPC module on the lab bench and use an electronic leak detector to locate the leaky component on the module 16 of 20 inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Column Inlet 230 Leak testing EPC and manual inlets Ribbon cable from leak test kit AON To gas supply WX LON Figure 230 10 Leak testing the EPC
11. test block part no G1530 20660 from the leak test kit part no G1530 60960 Make sure you install O rings between the block and the EPC module to create a seal The leak test block is a special fitting that plumbs the carrier gas coming out of the module directly back into the septum purge flow path on the module It allows the carrier gas and septum purge to function normally as if an inlet were present 4 Perform the normal leak test for the EPC inlet as described previously in this section With the inlet removed the internal volume is smaller and a pressure loss of 1 0 psi in 10 minutes is considered leak free Forward pressure valve leaks Occasionally an increase in pressure rather than a decrease may be observed This is usually due to slight leakage into the module across the forward pressure control proportional valve Although slight leaks of this nature do not create chromatographic problems they may obscure other small leaks that do cause problems by allowing air into the system To check for internal valve leakage 1 Remove the supply pressure at the carrier inlet fitting and quickly cap the fitting with a Solid 1 8 inch Vespel plug and a Swagelok nut Jun 2001 Inlets 15 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Leak testing EPC and manual inlets 2 Check the actual pressure on the display and monitor it for 10 minutes Pressure loss should not be greater than 0 5 psi L
12. urn the inlet pressure Off Press Front Inlet or Back Inlet scroll to the Pressure field and press OFF FRONT INLET coc Mode Track oven l Temp 150 150 24 6 off lt 4 Note the Actual reading on the display and monitor the pressure for 10 minutes 12 of 20 inlets Jun 2001 Agilent 6890 Gas Chromatograph Service Manual Cool On Column Inlet 230 Leak testing EPC and manual inlets You can use the stopwatch feature of the 6890 GC to monitor the time Press Time and then Enter to start timing then toggle between the time and the pressure reading with the Time and the Front Inlet Back Inlet keys If there is less than 1 0 psi pressure loss approximately 0 1 psi min consider the system leak tight If pressure loss is much greater than1 0 psi there is a leak that must be found and corrected See Correcting leaks later in this section When the system is considered leak tight the caps may be removed the column reinstalled its dimensions configured at keyboard and the desired pressure set Jun 2001 Inlets 13 of 20 Agilent 6890 Gas Chromatograph Service Manual 230 Cool On Column Inlet Leak testing EPC and manual inlets Performing the leak test manual inlets Note Be sure that the preparation steps on pages 10 and 11 are complete before proceeding with this test 1 Turn the pressure controller clockwise until the column head pressure reaches 25 psi
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