"Many process analyzer sampling systems in today’s plants are not fulfilling their intended purpose, which is to deliver an uncontaminated, representative sample to the analyzer without excessive time delay. The result is ... inaccurate analyzer readings,...chemical and petrochemical products that are not within specifications, ...[and] safety issues."
- Dean Slejko, Swagelok Co and Tony Waters, Sampling System Expert
In the past 50 years, process analyzers of all kinds have gotten better and better, but sampling systems haven't. Many don't even fulfill their intended purpose, which is to deliver an uncontaminated, representative sample to the analyzer without excessive time delay.
The result is compromised or inaccurate analyzer readings and, by extension, chemical and petrochemical products that are not within specifications. Why? The problem can be boiled down to three main reasons.
To our knowledge, there are no university programs that provide courses dedicated to sampling system engineering. In addition, there’s little opportunity to learn on the job. Few engineers and technicians can spare the time to attend even a one-week training course.
As a result, many major industrial companies outsourced the work to system design and fabrication specialty firms. However, even these firms have few people with the necessary skills. Inexperienced design engineers can make mistakes that may get past the reviewing engineer, who knows even less about the system. Then, if the operators need to make on-site adjustments, the designers may never learn from their mistakes.
Why Sampling Systems Haven't Improved - Three Main Reasons (Full Article)
Plants often consider a sampling system to be an add-on module that can be plugged into a larger system without much thought. But that ignores the process taps, the transport lines, and all the other devices that ensure the sample a suitable condition for the analyzer.
A single error along the way can bring the whole system down, and they may not be evident until the plant is at full capacity, the control loop is closed, or the laboratory results are available.
Most industrial plants forbid ad hoc changes to system designs. However, supervisors often push maintenance technicians to make adjustments. In this case, technicians may experiment with sampling system changes until the system seems to work better. But if the sampling system never really worked in the first place, these unauthorized changes can cause more problems than they solve.
Industrial Sampling Systems, the definitive reference guide by expert Tony Waters (book excerpt)
So how can plants improve the quality of their sampling systems?
Swagelok can help in many of these areas. First, we have a three-page technical paper that goes into more detail about the areas we touched on in this post. It includes a list of analytical goals and operational goals for sampling excellence.
Swagelok Grab Sampling Systems Application Guide (Catalog)
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