Archive for category pressure transmitters
Minimizing shift on a draft range differential pressure transmitter
Posted by danstips in Honeywell, Pressure Transmitters, pressure transmitters, Transmitters, Troubleshooting on August 19, 2014
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?”
Tips for ranging a vacuum transmitter
Posted by danstips in 4-20mA, Honeywell, Pressure, Pressure Gauges, Pressure Transmitters, pressure transmitters, Siemens, Transmitters, WIKA on July 31, 2014
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?
Honeywell smart transmitter design makes communication card swap easy
Posted by danstips in Communications, Configuration, HART, Honeywell, Honeywell DE, Pressure Transmitters, pressure transmitters, Service, Transmitters, Troubleshooting on January 28, 2014
It was bound to happen sooner or later.
I took a call from a customer who needed to replace a garden variety differential pressure transmitter… with one exception: He needed Honeywell’s DE digital protocol for communicating to his DCS. The DE protocol is still great, but since so many installations today use HART or Foundation Fieldbus, all of our in-stock pressure transmitters had a HART communication card – a critical mismatch to what the customer needed.
A year ago, we would have been stuck rush-ordering a unit from the factory, with all the attendant delays and expediting charges, because you couldn’t swap out a comms card without making the transmitter’s hazardous approval invalid.
What could we do?
Read the rest of this entry »
Wet rhymes with Set (or how to remember LRV/URV configuration prompts)
Posted by danstips in Configuration, Honeywell, Installation, Level Transmitters, Pressure, Pressure Transmitters, pressure transmitters, Siemens, Transmitters on July 26, 2013
Lots of people like the pushbuttons on industrial pressure transmitters because the basic settings that every transmitter needs can be set up without a HART communicator. This includes things like the tag name, engineering units, LRV (Lower Range Value, the zero, or what 4.0mA represents), URV (Upper Range Value, the span, or what 20.0mA represents) and damping (an average or filter factor that dampens noise).
On the new Honeywell ST700/ST800 series smart transmitters, the tag name and engineering units are easy to configure and self explanatory, but I seem to stumble when setting up the LRV and URV because I’m faced with a non-descript choice. There’s two sets of options (under Transmitter Setup, not Calibration):
Enter LRV
Enter URV
Set LRV
Set URV
OK, either configures an LRV or a URV value, but which is which? What’s the difference?
Comparing Honeywell smart transmitters
Posted by danstips in Honeywell, Measurement, Pressure Transmitters, pressure transmitters, Transmitters, Uncategorized on February 12, 2013
Honeywell’s new SmartLine ST700 and ST800 pressure transmitter lines are replacing the existing ST3000 100 and 900 series.
If you’re using ST3000 100 series transmitters, you’ll be looking at the ST800 for future units. If you’re using the ST3000 900 series, the ST700 will be your better fit.
What does NAMUR NE 43 do for me?
Posted by danstips in Honeywell, Level, Level Technology, Measurement, NAMUR, Pressure, Pressure Transmitters, pressure transmitters, Process terminology, Siemens, Standards, Transmitters on February 17, 2012
People have asked me about setting fault alarms in level transmitter analog signals at 2mA or 3mA levels. What they typically don’t understand is that a two-wire transmitter uses the electrical current below 3.6 mA for its own power and operation. So, a 2.0 mA or 3.0 mA fault indication just isn’t possible. At these low currents, there wouldn’t be enough power to generate the fault indication signal and to keep the transmitter functioning properly. Read the rest of this entry »
Should I use a chemical seal with my pressure instruments?
Posted by danstips in Honeywell, Pressure, Pressure Gauges, Pressure Switches, pressure switches, Pressure Transmitters, pressure transmitters, Siemens, Switches, Transmitters, United Electric, WIKA on January 17, 2012
Pressure instruments in contact with the process can take a real beating. Process fluids can corrode the wetted parts and destroy the sensing element. Media the solidifies can clog the pressure-sensing port. Or, an installed instrument can affect the process by providing a spot for media remnants to remain after cleaning and purging. Specialized chemical seals deal with these pressure sensing issues.
Here’s a list of questions to ask about your application that will determine if you need a chemical seal with your gauge, switch, or transmitter.
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