Don’t forget about your lab’s moisture traps/filters, especially when it’s summer

One of the common issues which arise in laboratories during the summer is moisture in the gas lines. Although I never quite understood how this would happen when using gas cylinders, it does, especially when a manifold system is used, or if the length of tubing from the gas source to the instrument is longer than several feet/meters.  Common observations when this happens are:

Unstable instrument detectors (especially TCDs, HIDs, ECDs and mass specs).

Less than ideal chromatography (shifting retention times, unusual peak shapes, etc.).

Unusual activity issues in the injection port and/or ghost peaks.

 So what is an inexpensive way to minimize these issues, especially in the summer when many locations experience hot and humid conditions? Install an indicating moisture trap/filter on all gas lines.

So how would you know which trap filter would be best for you laboratory? Ask yourself the following questions:

Q1. What is the gas?

Q2. Is the gas line tubing copper or stainless steel?

Q3. What is the maximum gas flow rate the trap/filter may be subjected to?

Q4. What is the maximum gas pressure the trap/filter may be subjected to?

 

Here are my suggestions to aid in trap/filter selection based upon the questions listed above:

S1. Generally speaking, the traps/filters we sell are for use with laboratory grade (high purity) inert gases.  If you plan to use a Restek trap/filter with a corrosive, flammable or reactive gas, email technical service.

S2. Most use traps/filters containing brass end-fittings with copper tubing and stainless steel end-fittings with stainless steel tubing.  For additional information on the topic, I suggest you review the post "I need a fitting, but which one?"

S3. Published flow rates can vary among manufacturers, so make sure you are aware of exactly what a published value represents.  For example, is the published flow rate the maximum flow rate the trap/filter can handle, or is it the maximum flow rate in which the trap/filter can effectively clean (scrub) the gas?  In the context of this post, what is the maximum gas flow rate through the trap/filter that can effectively remove much of the moisture?

S4. For obvious safety reasons, make sure the published maximum trap/filter pressure is not exceeded.

 

Several of the popular indicating moisture filters are shown below.

 

Indicating Moisture Traps (Inline)

 

 

Restek Super Clean Ultra-High Capacity Moisture Filter (needs baseplate)

 

 

Single position baseplate

 

 

 

 

 

 

 

Of course, we also sell a wide variety of other filters including non-indicating moisture filters, and others for the removal of oxygen and/or hydrocarbons.  You have plenty of choices from Restek.