Designed strictly for gas-phase samples, Micro GCs require robust sample conditioning to prevent damage from liquids and particulates—making low-volume bypass membrane filters the standard solution for front-end instrument protection.
How to guarantee the protection of the micro GC?
Because Micro GC systems are dedicated strictly to gas analysis, introducing liquids or solid particulates can cause severe instrument damage. The membrane filter serves as your analyzer's primary defense line. Featuring a ultra-low internal volume bypass design, it holds back liquids while a porous sinter captures fine particulates
How Often Should You Maintain the Membrane Filter?
Maintenance frequency depends directly on sample matrix quality and analysis duty cycle.
First Check: Inspect the membrane 3 to 6 months after commissioning (if no liquid ingress is suspected).Adjust Interval: If clean, extend the inspection interval; if contaminated, reduce it.Absolute Rule: Check and replace the membrane at least once a year.
Immediate Action: Whenever liquid contamination or particulate overload is suspected, inspect the filter immediately.
Step-by-Step Maintenance Guide
⚠️ Safety First: If your membrane filter is heated, turn off the heating zone and allow the assembly to cool down completely before handling.
Always work in a clean environment.
Required Tools & Parts:
- Replacement Membrane (Chemlys P/N: 7612)
- Flat key 5/16"
- Flat key 1/4"
- Allen key 9/64"
1. Disconnect Tubing: Use the 1/4″ wrench to remove sample lines connected to the filter.
2. Unmount Filter: Use the 5/16″ wrench to disconnect the filter assembly from the Micro GC inlet.
3. Remove from Support: Unscrew the bottom mounting screws using the 9/64″ Allen key.
4. Open Enclosure: Remove the top housing screws with the Allen key to expose the membrane.
5. Inspect Membrane Condition:
- Clean membrane on both sides: No contamination detected
- Dirty on the inlet side, clean on the outlet side: Contaminants were successfully trapped and did not breach the membrane.
- Dirty on both sides: Contamination breached the membrane—potential risk of Micro GC contamination.
6. Clean Components: If residue is present on internal filter surfaces, clean housing parts with isopropanol and dry completely.
Replace the frit (P/N: 6912) or tubing if traces of pollution remain.
If tubing exhibits any signs of contamination, replace it immediately.
7. Insert New Membrane: Verify the frit is properly seated on the outlet side. Center a new membrane (P/N: 7612) over the housing.
Note: Never reuse an opened membrane, even if it appears clean, as its sealing integrity is permanently compromised.
8. Reassemble Housing: Align the inlet cover over the centered membrane and tighten screws evenly to ensure a gas-tight seal.
Reinstall the filter on its mounting bracket, reconnect to the Micro GC inlet, and reattach all sample line fittings.
How Can I Ensure the Membrane Filter Is Correctly Reassembled and Leak-Tight?
Once membrane filter maintenance is complete, verifying system tightness is strongly recommended. Indeed, a leak can cause:
- Ambient air contamination (O₂ and N₂) appearing in analytical results despite absent matrix levels
- Under-quantification of target compounds
- Sample venting into the laboratory atmosphere (a critical safety hazard, especially when analyzing toxic compounds)
To verify this, we recommend using an electronic leak detector. Liquid leak detectors (such as Snoop® or soapy solutions) must be strictly avoided to prevent contamination of your tubing and Micro GC system. !
Proceed as follows:
- Cap one of the two membrane filter ports with a Valco® plug.
- Connect a regulated gas supply to the remaining port. Helium at 1 barg is recommended for this test.(Reminder: The maximum allowable inlet pressure for the Micro GC is 2 barg. Exceeding this limit poses a high risk of damaging the module injectors!)
- Run the electronic leak detector probe across all critical areas: filter fitting nuts, the Micro GC inlet nut, and the sealing interface between the two halves of the filter body. Retighten any screws or nuts as necessary to stop detected leaks.
See also: How to connect and purge a carrier gas regulator
Due to multiple mountings/disassembly of the membrane filter, leaks may persist even after tightening the nuts. This can be caused by ferrules too crushed with tightening. Their replacement is then necessary.
What to Do If Liquid Entered the Micro GC?
If liquid has passed through the filter into the Micro GC, simply replacing the membrane is not enough. Trapped liquid inside internal manifolds or micro-columns will cause baseline drift, detector contamination, or severe hardware failure.Immediate Next Steps:- Stop current analytical runs immediately.- Power down sample flow.- Open a support ticket on the Chemlys Digital Portal to receive guided recovery instructions from our service engineers.
