For high-purity GC and GC/MS carrier gas, we always recommend metal or shielded-glass purifiers such as our AFS and ZPure lines. But there are countless non-GC applications in and out of the lab where clean, dry air or inert gas is needed. Examples include glove bags and boxes, desiccant chambers, and instrument purge gases to name a few. For these applications, plastic-body traps such as our SPure Line can provide a cost effective solution.
Let’s look at some of the characteristics of SPure general-purpose traps. First, in comparison with competitor traps designed around calcium sulfate (drierite) adsorbent:
-SPure plastic traps use a safer CoFree (cobalt free) moisture indicator to signal moisture depletion (EC classification not dangerous). Drierite traps contain cobalt chloride (per OSHA HCS- a suspected carcinogen and presumed human reproductive toxicant, and is also listed as a “Substance of Very High Concern” in the EU).
-SPures traps come with a wider variety of available fittings including standard compression fittings, quick-connect fittings, or push-to-connect fittings for plastic tubing. A right angle fittings option has recently been added on select filters that may help in some instrument configurations for more efficient replacement.
-SPures offer a choice of adsorbents for more specific contaminant removal: molecular sieve for high-efficiency water removal (and other contaminants with high affinity for molecular sieve), and activated charcoal with or without molecular sieve for broad-range organics removal.
-Four different sizes in all configurations for a range of capacities and flow rates. We can help determine which is best suited for your specifications.
-Quick and easy refill process.
When compared to carrier-grade metal or shielded-glass purifiers there may be applications in which plastic traps can be substituted. However, there are important differences that need to be considered:
-SPure plastic traps have only a single wall, the purifier body itself. If this body cracks or breaks, gas can escape. For this reason, we don’t recommend use of SPure plastic traps with hazardous or flammable gases such as hydrogen. For theses applications, we instead recommend our shielded-glass purifiers because of their double-wall construction. Of course, one still needs to keep the maximum pressure specification in mind when using any purifier, even the metal-bodied lines.
-Plastics are generally not resistant to solvents. Direct exposure of the plastic body to solvents isn’t likely, but depending on the gas stream, a buildup of solvents over time could come in contact with the inner wall. An example of this is oils collected downstream from a house air compressor. If you see any liquid or condensation in the purifier, it is time to replace it.
-SPure traps do use less sensitive indicators. Because plastics are slightly permeable to air and water, our most-sensitive indicators can’t be used with them. So instead of using our HSMI moisture indicator, which turns color at less than 1 ppm with water, we use CoFree, which turns at higher concentrations. It is useful though to show big leaks in the gas line, or saturation if the incoming gas has high water content.
-SPure traps are not as robust and not suitable for outdooe use; plastics are sensitive to long-term UV exposure.
While they are not suitable for every application, SPure traps can be an appropriate and cost-effective solution, when keeping their limitations in mind.
We are here to help with your questions. Please reach out to us by phone, email, or online chat regarding which trap is best for your specific application.