There is a myriad of devices to measure and control temperature in the process industries. Everything from tiny sensors to high-level controllers is available to the user. Much of the buzz right now is over wireless sensing, but not everyone is convinced of its applicability, particularly in certain applications.
Using wireless in critical temperature applications is still the subject of serious debate. Some closed-loop control applications are compatible with current wireless communications; others require update frequencies of less than one second and pose higher transmission robustness requirements, making them incompatible with current battery-powered wireless sensing. This presents a challenge for future development. But standards organizations and manufacturers are addressing these issues with the aim of producing affordable wireless solutions that will work well in heavy industrial applications.
According to a market research study from Frost & Sullivan, “wireless sensing is of crucial use in hard-to-reach or hard-to-wire applications. In the industrial automation space, the largest opportunity for wireless sensor networks is as sensing devices in remote or inaccessible areas such as nuclear plants, oil and gas fields and high-temperature furnaces. Among the various sensors, temperature, pressure and flow sensors remain the dominant technologies”.
In a recent market intelligence study on fieldbus networks, produced by Control, 24% of the respondents currently use wireless. Nine percent plan to use the WirelessHART protocol, while 50% are unsure of its applicability. Sixty percent believe that WirelessHART would make it easier to get diagnostics and calibration data from their instrumentation, but only 24% say they are likely to use it for such purposes. Half are unsure, while 26% say they are unlikely to use the protocol to gather additional diagnostics and calibration data.
The pros and cons of wireless temperature measurement are being debated in many board rooms, engineering departments and marketing departments, as we speak. As long as users can receive reliable temperature measurements using wireless in a critical environment, everyone needs to keep an open mind.
Forget About Corrosion
iTEMP TMT162 smart temperature transmitter is equipped with corrosion prevention and resistance and has a stainless steel housing. It is capable of single- or dual-sensor input, meaning the transmitter is capable of accepting input from two different sensors at the same time. In addition to the stainless steel housing, corrosion protection detects corrosion on thermocouples and RTDs before it corrupts measured values, which allows for maintenance intervention and avoids a potential shutdown. Endress+Hauser; 317/535-7138; www.us.endress.com
Temperature Measurement of Liquid Hydrocarbons
ACCU-TEMP Type M tank measurement sensor can be permanently installed in a tank for temperature measurement of liquid hydrocarbons. It determines either average or multiple-spot temperature. Designed for direct immersion, the sensor is built of flexible, corrosion-resistant stainless steel and Monel annular-ring hose. It requires only one tank entry opening. Various tank entry connections and terminal enclosures are available. Weed Instrument; 512/434-2800; www.weedinstrument.com
Ti50 and Ti55 IR FlexCam thermal imagers combine 320 x 240 pixel resolution with a 5 in. high LCD display. They have new analysis and reporting software with features such as a 25-micron, 320 x 240 uncooled vanadium oxide (VOx) microbolometer detector, thermal sensitivity of 0.05 ºC NETD for the Ti55 and less than 0.07 ºC NETD for the Ti50, on-camera Windows CE interface and interchangeable optional angle and telephoto lenses. Temperature measurement range is 600 ºC and image capture rate is 60 Hz for real-time target temperature displayed live on the camera’s screen. Fluke; 800/760-4523; www.fluke.com
Mini Infrared Transmitters
OS100E Series miniature infrared transmitters measure a temperature range of -18 ºC to +538 ºC (0 ºF to 1000 ºF). All models have a remotely mounted infrared sensor head connected to a microprocessor-based signal conditioner. The sensor head measures temperature in confined, hard-to-reach places and harsh ewnvironmnts. Available models include 4-20 mA, 0-5 Vdc, 0-10 Vdc, 1 mv/deg and Type K thermocouple. Omega Engineering; 203/359-1660; www.omega.com
MicroRay HVAC++ portable infrared thermometer is three instruments in one. It measures humidity, surface temperature and ambient temperature. Temperature ranges are -22 ºF to +1,112 ºF. It has a built-in T+H sensor, 64 internal-test memory, PC software capabilities, a “hold” function, high/low alarms and adjustable emissitivity. E Instruments Group; 215/750-1212; www.einstrumentsgroup.com
Flexible Temperature Sensor
WORM flexible sensors replace restrictive straight sensor probes and install without removing the transmitter enclosure or union components. It bends around and through the top face of the enclosure. It then slides through the enclosure’s entry port and snaps into place without removal of the enclosure, rigid conduit, connection head or any assembly components. Using the WORM, there is no need to stock an expensive collection of different sensors. Sensors are available with a variety of RTDs and thermocouples, including 100 and 1000 ohm, platinum, copper, nickel RTDs, J- and K-type thermocouples and others. Moore Industries International; 818/894-7111; www.miinet.com
Wireless Temperature Solution
Rosemount 648 wireless temperature transmitter is suited for monitoring applications, especially in hard-to-reach or cost prohibitive locations. It can be configured for a variety of sensor inputs including thermocouples, RTDs, ohms, millivolt and RTD sensor matching (CVD). SmartPower extends the battery life of the transmitter while still delivering HART data and diagnostic information. Emerson Process; 800/999-9307; www.emersonprocess.com/smartwireless
Temperature Control Consoles
TPC 1 to 4 zone portable temperature control consoles are pre-built self-contained systems, Designed around the TEC-9100 1/16 DIN temperature controllers, the consoles are easy to program and offer auto-tuning fuzzy logic PID heat control. Tempco Electric Heater; 800/323-6859; http://www.tempco.com/