July 2008

Focus on temperature

The temperature of an object is that which determines the sensation of warmth or coldness felt from contact with it. In the early 18th century, Gabriel Fahrenheit adapted a thermometer and a scale-temperature measurement using these instruments goes back at least this far. The Fahrenheit scale is still in use today, as are the Celsius and Kelvin scales.

Temperature transmitters

The DSCP20 and SCTP20 loop powered software configurable temperature transmitters are designed around an ASIC chip specifically engineered for thermocouple and RTD sensor interface. The ASIC design provides a high degree of versatility, allowing customer configuration of eight operational functions, selection of 12 industry standard thermocouple types and three standard RTD types, and selection of 270 input ranges. All sensor inputs are linearized using a 23-point interpolation table.

The transmitters are loop powered, deriving their power from the input signal.  Two separate package designs allow for installation into head mount housings in accordance with the DIN 43 729 standard or mounting to DIN rails. Models are available in either non-isolated or isolated versions.  The ASIC-based transmitters are designed to protect valuable measurement and control signals as well as connected equipment from the dangerous and degrading effects of noise, transient power surges, internal ground loops, and other hazards present in industrial environments.

The transmitters can be easily configured to the specific measuring task with a PC, an interface cable, and the menu-driven DSCX-895 configuration software that runs on Windows NT, 2000, and XP. Communication is serial RS-232C, and all models can be configured with or without their power supply connected. 

Dataforth
www.dataforth.com

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Cooling element

The Sta-Kool cooling element was designed specifically with high temperature processing environments in mind. Under laboratory test conditions, the 316L stainless steel Sta-Kool cooling element was able to reduce 400oF (204°C) liquid process temperatures to 100°F (38°C) at the active portion of the Bourdon tube.

The Sta-Kool cooling element has a maximum operating temperature of 750°F (400°C) at 3,500 PSI operating pressure and a maximum operating pressure of 5,000 PSI at 100°F.  It can be either threaded or welded (to eliminate a potential leak path) to any pressure gauge with ½" NPT male connection made from a compatible material. In addition, the Sta-Kool element can be attached in between a pressure gauge and diaphragm seal for the most comprehensive process measurement protection possible, protecting the instrument from both pulsation and temperature extremes.

AMETEK U.S. Gauge
www.ametekusg.com

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Vortex shedding flowmeters

The CoolPoint vortex shedding flowmeters with a temperature transmitter for measuring and monitoring both flow and temperature in industrial processing operations are designed for flow applications involving heat removal.  CoolPoint measures the flow rate of cooling water, water/glycol coolant, or low-viscosity fluids.  Meters with the transmitter have the added capability of monitoring temperature readings and transmitting them to a process controller.

The flowmeters with temperature transmitter are available in pipe sizes ranging from 3/4 inch (maximum flow rate 25 gallons per minute, 95 liters per minute) to 4 inches (maximum 600 GPM, 2271 LPM). These meters provide temperature readouts ranging from 32°F to 210°F, which can be expressed in either Fahrenheit or Celsius on the local LED readout. 

CoolPoint meters provide the flow repeatability and accuracy that help achieve process control.  Flow and temperature repeatability of +/-.25 percent (1/4 of 1 percent) of indicated flow is standard.  Flow accuracy of +/-2 percent full-scale and temperature accuracy of +/-1 percent FS are standard.  Flow accuracy of +/-1 percent FS is an option on temperature-transmitter models in 3/4 inch through 2 inch pipe sizes.

Universal Flow Monitors, Inc.
www.flowmeters.com

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