Twin Switches for Pressure and Temperature

A New-Generation Replacement for Your Old Mechanical Switches

There are tens of thousands of aging, mechanically-based pressure and temperature measurement switches out there operating in factory automation, machine tools, and in process equipment skids serving the chemical, food & beverage and pharmaceutical industries, to name a few.


New generations of process equipment demand a change to electronic switches,you hear that from customers all the time. Likewise, just as you'd upgrade a controller as part of a customer retrofit, it's prudent to replace those legacy sensing units when the opportunity arises. Old mechanical switches in operation today inevitably suffer from component fatigue that leads to poor reproducibility and inaccuracy. Besides being more reliable, electronic switches can offer advantages such as flexible programming, self-diagnostics, PC-compatibility, etc.


Endress+Hauser says it's ready when you are and say replacing old-fashioned mechanical switches doesn't have to be expensive. The company herein introduces the Ceraphant T/Thermophant T "twin" electronic switches that are intended for applications in those industries mentioned above.


Ceraphant T is an electronic switch designed for absolute and gauge pressure measurement. Thermophant T is an electronic switch designed for temperature measurement in gases, vapors and liquids.


"The design of these devices includes a unique AISI 316L stainless steel housing for resistance against chemical corrosion and mechanical abrasion," says Jerry Spindler, business development manager for Endress+Hauser's E-direct business. "The surface of the switch housing is electropolished to better than 0.8 ?m, resulting in easy and efficient cleaning. Many of the units are rated NEMA6P."


Ceraphant T PTC31 includes a 99.9% pure AI2O3 ceramic sensor diaphragm, made of Ceraphire, Endress+Hauser's exclusive material that enables improved corrosion and abrasion resistance in highly aggressive media. "Ceraphire is the perfect solution for pressure measurement in vacuum applications due to its mechanical strength, which also is extremely overload-resistant, offering long-term stability," says Spindler.


Modularity comes standard with the new twin switches and provides sealing with a standard O-ring instead of metal-on-metal. Sixteen available adapters allow these switches to install into virtually any process. The switches have versions that provide measurements in sanitary applications: PTP35 in pressure and TRT35 in temperature.


"The electronics were developed according to international standard IEC61508/SIL2, while the sanitary versions for the food and beverage and pharmaceutical industries use all FDA-approved materials and meet 3A sanitary standards," states Spindler. "The units also are UL/CSA-listed and carry the CE mark. The switches are designed to endure a short over-voltage, up to 1 KV, without inflicting harm to the switch or the user."


The digital display has four digits backlit with 14 segments, each enabling engineering units in bar, psi, MPa, kPa, ?C, and ?F. "The user also can access the device memory to display the total number of switch cycles, as well as the serial number, tag number, hardware version and software version," adds Spindler. "Instrument details,serial numbers, tags, etc.--and measuring range and switchpoint settings can be specified at the time of ordering and will be programmed at the factory to decrease commissioning time."


Field adjustments can include damping, delays and zeropoint adjustment. When the engineering units are changed, values are converted automatically. The display element also can be rotated mechanically 340? for proper orientation, and the software allows the digital display to be rotated up to 180? if necessary to more easily read the measured value.


Complete on-site commissioning can be done with three on-board pushbuttons common to many Endress+Hauser devices. An intuitive menu-guided setup should allow for easy and safe switch operation and includes password protection.


Switch characteristics can be set with a Hysteresis or a Window operation, and as either Normally Open or Normally Closed. In addition, adds Spindler, the outputs can be simulated manually during commissioning without having to start the process to verify the correct wiring connections to the higher-level control system.


"Our ReadWin2000 configuration software with a USB interface can be used for off-line setup via PC," says Spindler. "This is especially useful when needing to duplicate the programming on several different Endress+Hauser devices."


Output connections include M12 microconnectors, valve plug (ISO4400), or a permanently wired 15-ft. cable. Endress +Hauser foresees a starting price of around $200. Starting in Q4 2004, some models will be stocked for shipment in two business days.


For more information, call 888-ENDRESS, browse to

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