Cold Weather is Here

Best Practice Gas Sampling Procedures

While sampling Natural Gas (NG) and Renewable Natural Gas (RNG) requires some adjustments for cold weather, following proper procedures for sampling Raw Biogas in cold weather is critical to receiving accurate laboratory analysis results. 

Pumps

Typically, Raw Biogas is under little to no pressure, or a vacuum, and requires a pump to collect sample gas for analysis. For sampling methods that call for sorbent traps, impingers, filters, or SUMMA Canisters, best practice is to place the pump downstream of these devices.

For filling high-pressure cylinders, since the pump must be placed upstream, it should be heated to prevent condensation and sample gas should pass through a moisture trap in an ice bath prior to compression.

Sample Lines

In all cases, heating the sample lines is critical to prevent condensation, dropout of analytes, blockages, and freezing of sample lines.

Sorbent Traps

In addition to heated sample lines, the sorbent traps should have a heating blanket to prevent condensation inside the traps. While this is best practice for all sorbent traps, it is especially important for mercury (Hg) and ammonia (NH₃) sorbent traps.

Sulfur

Sulfur species are very reactive to moisture. Hydrogen sulfide (H₂S) is especially reactive and will almost immediately react with water to form sulfuric acid, with the subsequent laboratory analysis showing little to no H₂S. Beyond heated sample lines and heated pumps, if a Raw Biogas sample is collected in a high-pressure cylinder, the pressure and reduction in temperature during transportation will condense moisture and H₂S and other sulfur species will quickly react and disappear. 

To prevent this, sample gas is passed through a moisture trap in an ice bath to reduce moisture content, and then a SUMMA Canister under vacuum is used to pull in a sample from a bypass sample line. The SUMMA Canister is kept under vacuum during transportation, keeping the moisture in vapor phase and preventing any water formation.

At Ohio Lumex, our certified team of Field Service Technicians are trained and equipped for all types of weather. Please let us know how we can help you deliver fast, accurate and cost-effective sampling and laboratory analysis solutions.