Blogging team for Dan's Tips, the education and tech tips blog for Lesman Instrument Company
Everyone agrees that it’s good practice to keep a record of configurations and setups for any field instrument. I’m constantly recommending it to our customers for their transmitters, controllers, recorders, and other complex configurable devices.
Siemens clamp-on ultrasonic flowmeters even have a system in place to make this process easy. By connecting the meter to a PC through the RS-232 serial port, you can use a terminal program and the SITE command to fetch a data file that holds all the instrument’s configuration data.
The terminal program can also be used — with a set of instructions specific to the flowmeter — for viewing real-time operational data, performing device setup, uploading logger data, or uploading configurations known as SITE setups.
Recently, I was called to visit a plant and look at a misbehaving flowmeter. From previous discussions with the operator, I knew he’d saved SITE setup files for every flowmeter installed in the plant.
I asked if the customer would e-mail me the setup file before my visit, so I could check out how the flowmeter was set up. My request was met with a chuckle and “Well, if you really think it’s worth it…”
You’ve heard this phrase before: “It’s simple. But nobody said it would be easy.”
And this is exactly one of those cases.
The Honeywell UDC3500 digital controller can support up to four setpoint programs, the ramp/soak profiles used in batch control operations. But after configuring all four profiles, I was stuck on how to select the one I wanted the controller to use.
There’s no “Program Select” button on the keypad. So I was mystified on how I was going to select my setpoint profile program #3.
A while ago, I got a call from a customer who was having trouble with a differential pressure transmitter. He was using a draft range DP transmitter to measure the pressure in a combustion chamber, so it could be controlled with a damper. He had one port connected to the combustion chamber with impulse tubing, and the other (low side) was left open to the atmosphere.
He’d noticed that when a fork truck or other vehicle sped past the furnace – the transmitter was mounted next to a traffic lane — it cause the furnace pressure to momentarily dip downward, and cause the damper to oscillate.
He figured out that the air movement provided by the passing vehicle was creating a momentary pressure pulse on the low side port. These air movements were creating difficulty in maintaining furnace pressure.
So, he asked me, “How can we dampen the effect of the momentary pressure pulse?”
Recently, a customer and I were talking about his Honeywell X-series paperless recorder, and how the information was appearing in TrendManager PC software.
The graphs were showing data with the original pen scales, 0° to 500° F. But the recorder rarely, if ever, read below 100° or above 400°, so there was a lot of “white space” on the trend chart.
Could we do anything about it?
A process plant’s technician was mystified about how to get a typical gauge pressure transmitter to read in the vacuum range. “All our gauges are 0 to 30 inches mercury, and that’s what we need to transmitter output to be. But the transmitter you sent us just stays around 4mA when we pull a vacuum.”
We walked out to the reactor vessel to look at the installation. The transmitter’s Low side port was open, its high side port was plumbed into a tee along with a conventional bourdon tube pressure gauge reading gauge pressure vacuum.
I could see why he was confused. The mechanical gauge goes from 0 to 30. I asked what range he used to configure the pressure transmitter. His answer, “0 to 30 inches mercury, same as the mechanical gauge.”
So, what was happening?
Posted in Uncategorized on July 25, 2014
Unexpected moisture in your process lines can cause costly problems.
From corrosion, rust, and oxidation to frozen control lines, failed pneumatic systems, and increased wear on moving parts, the presence of unwanted water in your process lines and instrumentation can be incredibly damaging.
My associate over at RAECO spells it all out for you. Check it out!
Originally posted on Tom's Tips:
When someone mentions issues with moisture, the first thing that comes to my mind is mold. If your basement has ever flooded, you can relate. This article is not about that.
In the manufacturing and process world, moisture can cause significant problems, even in small concentrations. The phrase “water and oil don’t mix” came to being for a reason (well, technically it can under the right pressure, but you get the idea).
Water doesn’t always play well with others. It can cause corrosion in valves, pipes and motors. It will react with a number of chemicals like lithium, sodium, silver, ammonia, chlorine, hydrogen sulfide and sulfur dioxide. It can destroy catalysts in hydrocarbon and petrochemical processing. And of course, it will freeze.
So what does that mean to your processes?
- If you have pneumatic controls and tools, it can cause corrosion and can also plug pneumatic orifices, valves and actuators
- If you…
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