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The Fluid Systems Engineering and Management Blog

by Swagelok Northern California

Ten Sampling System Mistakes Harming Your Operations

by Jeff Hopkins, on 2/16/17 8:30 AM

In this blog, get a summary of the Swagelok white paper, Ten Sampling System Mistakes Harming Your Operations, then download the four page white paper to get the complete picture,  here »



Protect your operation by avoiding these sampling system mistakes


There are plenty enough challenges to managing an analytical instrumentation operation without unexpected downtime and maintenance costs. It takes a good sampling system design and good operations practices to keep the system performing well.

Check out these 10 mistakes that often are made with sampling systems. Avoid these, and you'll prevent a lot of headaches.

1. Check for simple errors.

Some mistakes are easy to spot, but can wreak havoc if you don't bother to look. They include reversed check valves blocking the sample flow, or a fast loop flowing backwards.

2. Too much volume upstream of the first regulator

High-pressure gas can cause condensation in the lines and actually slow things down because of gas compressibility. It can also be a safety concern if a component ever fails and causes rapid decompression.

3. Low liquid sampling pressure

Liquid samples are just the opposite. Too little pressure may release a dissolved gas, causing the liquid to bubble or foam.

4. Paying too little attention to surfaces

When sample fluid touches a surface, a few molecules stick. Loss of molecules due to absorption can spoil your sample. Pick the proper materials for filter elements, regulator diaphragms, tube walls, or gas cylinders.

5. Elastomer seals not compatible with sample fluids

Material that is mismatched to your sample fluid may cause a leak or even or even a blockage within the sampling device.

6. Sampling from a stagnant line

Samples always should come from an active process line, and should come from a point that gets the sample to the analyzer quickly.

7. Dead legs in the sample-transport line

Dead legs or unpurged volume allow molecules to diffuse into the sample causing a slow analyzer response and continuous contamination of the system.

8. The vaporizer is too hot

A hot vaporizer body could boil the incoming sample, causing it to fractionate.

9. The sample flow is too slow

The slower your sample flow, the more viscous drag is placed on the interior wall of your tubing, causing solids to form.

10. Not looking for the causes of time delay

If the measurement does not follow your process, you have time delay in your system. Other symptoms are blurred or muted response, laboratory disagreement, and poor performance of a control scheme. View a sample time delay calculation.

You can lean more details about these mistakes by clicking here to download a white paper, complete with links to examples and formulas.

Download the four page white paper to get the full story

White Paper: Ten Sampling System Mistakes Harming Your Operations


Additional Resources


Industrial Sampling Systems Book Excerpt


Swagelok Process Analyzer Sampling System Training Brochure


Topics:Sampling Systems

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