|David W. Spitzer|
The following article is the latest in a series based on the troubleshooting of a mysterious unit shutdown due to flowmeter performance problems.
I will admit that it was a sight to behold when I arrived at the unit … It was my second week at the plant, my supervisor and foreman were both coincidently on vacation, a unit had shut down, a flowmeter was the culprit, its control valve was covered with ice, the “midget-maker” was open (see “Back to Basics,” March 2014, page 14), and an apprehensive technician was waiting to greet me.
I had only met the technician in passing about a week earlier. I didn’t know his skill level, but I did know that he worked at the plant for a number of years. After formalities, the technician immediately pleaded with me not to have him check the flowmeter calibration and its functionality. I quickly got the feeling that he had “seen this movie before.”
Sensing that there was more to the issue at hand than met the eye, I did not give instructions to take action on a process that I didn’t know or understand. Rather, I had the technician explain the process and describe what had happened. The relevant portion of the process amounted to a flow control loop with a low-flow scram.
“What is a scram?” you might ask. I had never heard of a scram before this event either, and my first instinct was to leave the area (quickly). A few questions revealed that a scram was the plant term for removing feeds from the reactor under abnormal conditions so as to safely shut it down. In this instance, operation of the reactor with low feed flow was considered abnormal and caused the reactor to scram.
Over the years, I have come to respect technicians and operators for their ability to observe and relate events. In this instance, the flow of one reactor feed measured low flow and caused the reactor to scram.
Stay tuned for process operating conditions next month.
David W. Spitzer is a regular contributor to Flow Control magazine and a principal in Spitzer and Boyes, LLC offering engineering, seminars, strategic, marketing consulting, distribution consulting and expert witness services for manufacturing and automation companies. Spitzer and Boyes is also the publisher of the Industrial Automation Insider. David has more than 35 years of experience and has written over 10 books and 300 articles about flow measurement, instrumentation and process control.