Archive for category Pressure Gauges
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?
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.
Ever hear the expression, “They’re the guys who wrote the book”?
When you hear who it is that “wrote the book”, they immediately gain authority over the rest of the “guys in the field”. It means they’ve taken the time to pull the fundamentals and inner workings into a centralized place, and they have the confidence in their works to share it with the world.
When it comes to pressure gauges and temperature measurement instrumentation…