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):
OK, either configures an LRV or a URV value, but which is which? What’s the difference?