Several Things You May Not Know About our Super-Clean® Gas Filters


Recently one of the designers of the Super-Clean® Gas Filters spent some time with technical service and we were able to ask him some of common questions we get asked by customers. I thought I would share this information with you.



A.  The fittings used on the baseplates (and those for the inline filters) are not NPT (National Pipe Thread). He said the NPT threads do not seal well, so they decided to use fittings with parallel threads. If you need replacement fittings for your ba seplate, we sell them as custom products (custom numbers are below inbold print). Contact Customer Service for pricing and availability.  Note:  PTFE tape is not recommended for use on parallel threads.



Restek # 558626 : Brass, for 1/4-inch OD (outside diameter) copper tubing

Restek # 560824 : Brass, for 1/8-inch OD copper tubing

Restek # 556389 : Stainless Steel, for 1/4-inch OD stainless steel tubing

Restek # 560702 : Stainless Steel, for 1/8-inch OD stainless steel tubing



B.  Listed maximum flow rates were determined by measuring the outlet flow at the maximum pressure, and not the recommended gas flow through the trap/filter. To achieve the best results, keep the flow rate at or less than 2L/min (liters  per minute) for the baseplate filters inline filters, 8L/min or less for the Big Trap Filters, and 20L/min or less for the LC/MS Filter Systems.



C.  A common reason that a new trap will become quickly spent (saturated) is because the check-valve O-rings are cracked/split and are leaking because they are not inspected and/or replaced when the filter is replaced.



Replacement O-Rings for Cartridge Base Plates

Replacement O-Rings for Click-On In-line Super Clean Connectors

You may also want to review What are these O-rings for that I received with my baseplate trap?



D.  The lifetime of the trap/filter is largely dependent on the quality of the gas going into it. Keep in mind that a filter/trap does not remove 100% of a particular contaminant, it cleans the gas (generally speaking) an order of magnitude. For example, if the gas quality going in contains 10ppm (parts-per-million) of a particular contaminant, the quality of the gas leaving the filter/trap will contain approximately 1ppm of that contaminant if the gas flow rate is within recommended specifications (see B above).



E.  Restek baseplate filters/traps may not work with another manufacturer’s baseplate. In some cases, the metal and/or plastic ring which connects the filter to the baseplate may not have a hole large enough to fit over a Restek filter. To check if our  filters will fit, search the Restek website using the competitor’s part number. If found, the trap should fit onto the baseplate. If no search results are found, it likely will not.



To look at this another way, the opening of the Restek gray plastic sealing ring is approximately 38mm inside diameter; some of our competitor’s sealing rings have a smaller ID, and our traps/filters will not fit into a competitor’s sealing ring.



F.  All of these traps/filters are designed to be installed right next to the instrument (point-of-use) for best performance. Using one trap/filter for multiple instruments is discouraged because this will increase the number of fittings downstream of the filter which will increase the possibility of leaks.



G.  Personally I do not recommend that any gas filters/traps be used with hydrogen because it is a reactive gas, but if used with hydrogen, only 99.9999% and purer incoming gas quality was suggested, which you can only get from research-grade gas cylinders and hydrogen generators containing a palladium membrane (purifier).  According to what we were told, if too much moisture is present in the incoming gas stream, it may actually strip some of the trapped contaminates from the filter’s packing and release them back into the filtered gas stream.



To read more about choosing the correct H2 generator, please review Need some help choosing a hydrogen generator?



I hope you have found this information helpful and that this clarifies some of the more common questions we are asked by our customers. Feel free to emailsupport@restek.com for any additional questions you may have on these filters/traps.

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