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10 Places to Check for GC Gas Leaks

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Gas leaks are the bane of every gas chromatographer’s existence. Even the smallest leak can cause a loss in sensitivity, contaminate samples, damage columns and instruments, and lead to a lot of wasted time. So grab your electronic leak detector and join us as we explore 10 places to check for leaks to help keep your gas chromatograph in tip-top condition!

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Gas leaks are the bane of every gas chromatographer’s existence. Even the smallest leak can cause a loss in sensitivity, contaminate samples, damage columns and instruments, and lead to a lot of wasted time.  

In this Restek Tip, we’re going to explore 10 places you must check for leaks to keep your GC in tip-top condition. Let’s get started!  

Prior to leak checking a GC, we recommend you increase system pressure while the GC is cool to accentuate any potential leaks, making them easier to detect. You will also need a leak detector. Today we’ll be enlisting the help of Restek’s electronic leak detector. These tools are huge time savers and are very effective in helping you troubleshoot and maintain your gas chromatograph.  

Now that we’re ready, let’s hunt down those leaks!  

The Gas Supply 

Sometimes the leak isn’t immediately near your GC. Always check your cylinders, generators, and manifolds. Each of these should be the first place you check when you suspect a leak. Pay special attention after installing new gas cylinders, particularly around the regulator.  

The Gas Filter Connections 

Check for leaks any time you install new or replacement gas filters. If one of your gas filter compression fittings are leaking, check the fitting to make sure it is in good condition. Then tighten it appropriately.  

The Shutoff Valves 

Moving parts can be more prone to leaking as they age and wear, so be sure to check the shutoff valves. A replacement may be necessary if you find a leak.  

The EPC Connection 

All gases enter the GC through the EPC so it’s a critical spot to check for leaks. If you find a leak, ensure all the connections into the GC are clean and secure.  

The Split Vent Trap 

Often overlooked during routine maintenance, the split vent trap could easily be the source of your leak. Be sure to check that the fittings are nice and snug. A replacement might be necessary if the leak is still present.  

The Septum Nut 

Another common source of leaks is the septum. If the septum is leaking, first attempt to tighten the septum nut, but only to finger tight. If the nut is not the source, try the septum; it may need to be replaced.  

The Weldment and the Weldment Lines 

Check the weldment for leaks. If you detect a leak, it may be the result of an incorrectly tightened weldment, if so, retighten it. If a leak is still present, or detected around the weldment lines, it could indicate the presence of cracks. In this situation, the weldment should be replaced.  

The Reducing Nuts 

Temperature cycling can loosen nuts if they are not properly tightened. If a leak is found, simply retighten the nut.  

The Inlet and Detector Column Nuts 

Be sure to check the column nuts and fully tighten them if there is a leak. A damaged ferrule could also be the source of the leak and might need to be replaced. 

The Column Connectors 

Don’t forget the column! Column connectors are common sources for leaks, even if they are leak-free after initial installation. Check them regularly during use, reinstallation may be necessary if you discover a leak.  

Even if a leak is not detected at any of these spots, it is good practice to inspect and leak check your gas lines and instrument daily, paying close attention to critical seals.  

Experiencing other problems with your GC? Visit for more troubleshooting tips. Like and subscribe for more helpful content, and thank you for joining us for this Restek Tip!

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