Posts Tagged vacuum gauge
Chemical seals and fills are often necessary to protect your process instrumentation from harm. But the wait for a custom gauge-and-seal, switch-and-seal, or transmitter-and-seal combination could be an issue, keeping your process offline for longer than necessary, or costing a premium for quick delivery.
We’ve removed the potential for downtime and rush charges with our WIKA-certified assembly station, and improved stock of most popular transmitters, switches, gauges, diaphragm seals, and fill fluids. Lesman customers can experience next-day delivery on custom assemblies from in-stock instrumentation.
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?