Archive for category WIKA
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.
Our level products manufacturers have released several new instruments to make your measurement tasks easier, more efficient, and more effective. So, we’ve put together a new Lesman Level Products catalog to introduce you to the latest technology.
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In order to understand level readings, you must first comprehend how the instrument works. Three of the most common level-measuring techniques involve using a displacer, float, or differential pressure instrument.
Here’s the catch.
While each of these instruments can be used to report a level reading, none of them actually measure level.
I know what you’re thinking…
If none of these instruments measure level, how do we end up with a level reading? Read the rest of this entry »
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.
There’s no such thing as a fail-proof thermocouple. Over time, thermocouples fail. To compensate for that, a temperature controller will normally go into upscale burnout mode, and drive the furnace burner to low fire or turn down the SCRs. But then, you have to deal with the downtime, rework, or even the potential of losing product.
Not long ago, a plant operator called to see if there we had a way to work around this burnout mode, so he wasn’t wasting time and materials.
His heat treat load had almost finished its final soak when the control thermocouple broke open. The controller, as expected, drove the furnace burner to low fire. The operator then popped the controller into manual mode, so he could nurse the load through the remainder of its soak cycle. He used the temperature reading on a recorder, fed from a second, unbroken thermocouple in the protection tube as temperature indication for the load.
If the situation had happened in the middle of the night, it may not have been handled with the same attention the day-shift operator had provided.
So, he asked if there was any way to have the controller automatically “fail over” to a second thermocouple.