AS THE PUSH to develop faster, more sophisticated and more accurate sensors for industrial applications continues, the contemporary landscape shows that wire-based sensors still are the most popular (and sensible) choice for industrial machine builders, with bus networks used most commonly. This is the state of affairs according to widely varying market reports that nonetheless show industrial sensor technologies and markets slowly moving toward wireless.
Venture Development Corp., which will publish a new sensor market study this year, forecasts annual growth of 5.8% for both wired and wireless sensor types through 2007, with markets for photoelectric sensors comprising 41% of this total.
While competition between wired and wireless gradually has reduced costs, spurred ongoing technical developments, and made the overall market stronger, research shows the basic need remains for dependable devices that inspect with better throughput, higher sampling rates and longer stand-off distances without sacrificing accuracy.
Industry analysts note, however, it’s not likely wireless sensing will be widely adopted simply because it is the latest technology, but will be implemented when it proves to be a reliable, cost-effective tool that solves real problems in industrial applications.
Robert Hoskins, editor/publisher of Broadband Wireless Exchange (Dec. ’05), states, “Most industrial segments have been slow to embrace installation of wireless sensors for three reasons: no visible cost savings; non-use of existing infrastructure; and security concerns.” Hoskins points to manufacturing operations that use fiber-optic wiring that enables them to install wired sensors without much additional cost.
“Because wiring in process control is very detailed, wireless sensors add to the cost, irrespective of the embedded level of intelligence in the system or the sensor itself,” Hoskins says.
The study, Wireless Sensor Networks: Growing Markets, Accelerating Demand, by ON World shows wireless is slowly winning wider acceptance in industrial automation, with the number of wireless sensor networks in use worldwide expected to shoot up from just 246,000 deployed in 2005 to 4.1 million by 2010.
“Until recently, wireless sensor technology was a patchwork of incompatible systems from a variety of vendors,” says Amit Jain, technologies analyst at Frost & Sullivan. “With the evolution of industry standards and the deployment of lightweight wireless networking hardware, wireless technology has come of age.”
Researchers do agree that more industry standards are needed so software vendors have common ways of pulling sensor data from networks containing sensors of varying intelligence made by different vendors.
For now, recent advances made in sensor technology have been limited mostly to enhancements of existing products, as most of this round-up demonstrates. Sensor enclosures for specialty applications, and better protection measures against vibration and high temperatures, continue to evolve. In addition, new developments abound in laser-based measuring systems and smart sensors that incorporate onboard intelligence with new advances in semiconductors, sensor bus technology and miniaturization.
A Break in the Action
SIA inductive-ring sensors activate when a break or inconsistency is detected. Rings are available in diameters 5-100 mm, with LED indication, and NPN or PNP output. An on/off switch enhances performance with small, fast-moving objects by creating a fixed timing impulse. The sensors have an IP65 rating, a plastic housing, and have adjustable sensitivity. ASI; 877/650-5160; www.asi-ez.com
Sensing the Distance
UHZ ultrasonic sensors have a maximum sensing distance of 300 mm with an 18-30 VDC input supply range and PNP or NPN transistor output. FARS sensors are 18-mm, non-metal, tubular, diffuse sensors featuring background suppression. MQ AC diffuse photoelectric sensors fit in a standard 18-mm mounting bracket or mounting hole. All are IP67-rated, and feature electrical protection from short circuit, overvoltage and reverse polarity. AutomationDirect; 800/633-0405; www.automationdirect.com
Setting a World Standard
QS18LD laser-diffuse and QS18LLP laser, retro-reflective sensors use visible Class 1 lasers, tightly collimated sensing beams and extended sensing ranges. Both use standard housings for mounting and application flexibility. Diffuse senses targets up to 300 mm, and retro-reflective delivers sensing to 10 m. It has status LEDs visible from 360° and six connector options. Banner Engineering; 888/373-6767; www.bannerengineering.com
Time to Unwind
Uprox+ sensors have a multi-coil system that replaces wound-coil systems found in conventional ferrite-core, inductive sensors. The sensors have an integrated pre-damping protection function to reduce the metal-free mounting area, allowing traditionally flush-mounted sensors to be recessed by half a turn for increased mechanical protection. All sensors adhere to EN50082-2. Turck; 800/544-PROX; www.turck.com
Protection Where You Need It
MgO thermocouples are constructed with the element compacted in high-temperature magnesium oxide, and protected by an integral metal sheath. Stainless steel and nickel alloy are available as sheath materials for specific application requirements. Diameters range 0.02-.500 in. Termination options range from standard male plugs to screw-cover terminal housings. Durex Industries; 847/639-5600; www.durexindustries.com
All-in-One System
Easytemp TSM 470 RTD has a four-wire Pt 100 Class A sensor available in different lengths for monitoring temperature in tanks and pipes. The unit has a built-in 4-20 mA integral transmitter with threaded or a clean-in-place process connection. The unit is available with preset or configurable measuring ranges. All process wetted parts are 316L stainless steel. Endress+Hauser; 888/ENDRESS; www.us.endress.com
Two Eyes Are Better
M180 flow switch with thermal mass flow sensor can be used for equipment flowing, dispensing or measuring corrosive fluids. The switch can be used for level or interface detection and alarm for harsh fluids, and has wetted materials available in either CPVC/Hastelloy C-22 or 316SS/Hastelloy C-22 combinations. Two platinum RTD sensors are mounted in fully sealed, miniature thermowells. Seven different standard configurations match specific OEM design criteria. FCI; 800/863-8703; www.fluidcomponents.com
ThermoVision
A40 series infrared cameras provide accuracy for industrial product and process monitoring, product verification and security applications. Featuring high-resolution, real-time imaging and built-in logic, the cameras offer a complete machine vision and remote monitoring solution that immediately identifies thermal problems that are otherwise undetectable. Flir Systems; 978/901-8315; www.flirthermography.com
Take a Picture
SA1E photoelectric sensors are available as through-beam, polarized retro-reflective, diffuse-reflected and small-beam reflective types. Sensing ranges from 10 m for the through-beam type, and 50-100 mm for the small-beam reflective type. Each has four styles in either cable or M8 connections, and Light ON or Dark ON operation models. All are CE-marked, IP67-rated and water-resistant. IDEC; 800/262-IDEC; www.idec.com
An Eye on the Temperature
Worm flexible temperature sensors mount anywhere a surface temperature measurement is needed. Sensors trim to any length, eliminating the need to stock varying lengths. Temperature assemblies keep the spring-loaded sensor in place, shielding it from external ambient temperature effects. Units come with a choice of temperature assemblies. Models without transmitters are available, as are RTD and thermocouple options. Moore Industries-International; 818/894-7111; www.miinet.com
Thermocouples Probes
Super OmegaClad XL probes provide high-temperature measurement with very low drift, and are available in K and N thermocouple calibrations. The thermocouple probes are offered in handle, molded-junction, quick-disconnect and heavy-duty styles. Omega Engineering; 203/359-1660; www.omega.com
In Close Proximity
E2A modular proximity sensors have extended sensing ranges, thicker barrels and one-piece construction. Sensors are available in M8, M12, M18 and M30 sizes in shielded or unshielded construction, and have NPN or PNP outputs, a range of barrel sizes and materials, and a choice of wiring options. Sensing distances range 2-30 mm. Extended-range allows device mounting further from tooling and work pieces, eliminating collisions and subsequent damage to sensors. Omron Electronics; 800/55-OMRON; www.omron.com
Double-Sheeted Detectors
Ultrasonic through-beam sensors identify misfeeds where distinctions are required to protect machinery and/or avoid waste. The 18-mm, double-sheet detectors are IP67-rated and detect 0-2 sheets of material with weights from 10-2,000 g/m2. Sensors have a teach mode, adjustable detection threshold for thick material applications, and insensitivity to printing, colors and glossy surfaces. Pepperl+Fuchs; 330/486-0001; www.am.pepperl-fuchs.com
Hold On Tight
Model 571A loop-powered vibration sensor monitors machine vibrations in hazardous areas to warn of increasing machine vibration levels, so preventive maintenance can be scheduled before failures can happen. All sensors are CSA-certified for the U.S. and Canada, and are ATEX-certified and RoHS-compliant for Europe. Robertshaw; 865/981-3092; www.robertshawindustrial.com
Predictive Maintenance Toolset
XM vibration I/O modules provide real-time monitoring of overall vibration levels. Deployed as standalone monitors or as part of a network, the modules provide early warning of equipment or process degradation, and can be integrated via DeviceNet with other protection modules, PLCs, DCSs, CMSs and display devices. For standalone applications, the series includes comprehensive alarm logic per channel. Rockwell Automation; 800/223-5354; www.ra.rockwell.com
Industrial Mass Flow Controller
Max-Trak 180 industrial controller measures and controls gas mass flow rates 0-200 slpm, and up to 400 slpm upon request, in a 5-in. flow body. Accuracy is ±1% of full scale with a repeatability of ±0.2% of full scale. Features include digital and analog communication, genuine 50:1 turndown, low differential-pressure operation, and the ability to view and change critical parameters in the field. Sierra Instruments; 800/866-0200; www.sierrainstruments.com
Long-Range Plans
Series M position transducer provides long displacement range and multiple mounting options for high-volume applications. Available with a maximum range of 85 in., the transducer has a reduced displacement cable fleet angle that increases repeatability, and reduces cable overlap. SpaceAge Control; 661/273-3000; www.spaceagecontrol.com
Alert the Media
MediaGauge digital pressure gauges have an accuracy of ±0.25%, measure pressures 15-5,000 psi, and are well-suited for industrial and commercial applications. SSI Technologies; 608/757-2000; www.ssitechnologies.com
Mount and Protect
GuardHouse brackets for threaded-barrel photoelectric sensors hold diffuse, retro-reflective and through-beam sensors with protective tabs that provide protection from physical damage. Custom, standard and models for attachment fit most automation applications. Brackets are made of heavy-gauge stainless steel that resists corrosion, and meets FDA requirements. SoftNoze USA; 315/732-2726; www.softnoze.com
Simple Clip-On
Clip-on-mount TLS 100 capacitive, level sensor reduces installation time, and permits a wider adjustment band for sensitivity. The non-contact sensor detects the presence or absence of liquids at a chosen level in plastic tubes, rubber hoses, and small glass or plastic pipes. It can protect pumps from running dry, has no moving parts, and is not prone to wear. TLS 100 is designed to measure high dielectric, water-based liquids. E-T-A Circuit Protection; 800/462-9979; www.e-t-a.com
Programmable Sensor Monitors Motion
The Gemco 955 Brik Gen III programmable linear displacement transducer detects movement to 0.001 in. A simple programming unit provides calibration for changing the setting of zero and span. Its tri-color LED visual indicator verifies optimal magnet positioning, confirms active zones, and provides self-diagnostics of LDT functions. The sensor is available in a variety of transducer outputs and can be ordered in lengths to 180 in. Ametek; 800/635-0289; www.ametekapt.com
Vibration Transmitter in the Loop
The HI 5701VTE loop-powered vibration transmitter provides a 4-20 mA output proportional to vibration amplitude levels of 0-1, 0-2, or 0-3 ips peak--suitable for monitoring vibration levels on rotating or reciprocating equipment. The sensor has non-polarity wiring and a power supply requirement of 10 VDC, and provides both 4-20 mA and buffered outputs. Hardy Instruments; 800/821-5831; www.hardyinstruments.com
Take the Cable and Go Home
To help prevent unauthorized changes, the Telemecanique XUN “teachable” photoelectric sensor has a removable push button cable. The cable is used to program the sensor to operate in any of four sensing modes--background suppression, proximity diffuse, polarized retro-reflective and thru-beam. The sensing range of the sensor is 4.7 in. to 49.2 ft, depending on mode and can be panel-mounted or 18 mm thread-mounted. Schneider Electric; 704/916-6173; www.us.telemecanique.com
Programmable Sensor Monitors Motion
The Gemco 955 Brik Gen III programmable linear displacement transducer detects movement to 0.001 in. A simple programming unit provides calibration for changing the setting of zero and span. Its tri-color LED visual indicator verifies optimal magnet positioning, confirms active zones, and provides self-diagnostics of LDT functions. The sensor is available in a variety of transducer outputs and can be ordered in lengths to 180 in. Ametek; 800/635-0289; www.ametekapt.com
Runs Hot and Nasty
The MIH temperature sensor can be installed in environments to 356º F with no air-cooling required and withstands harsh chemical environments, making it suitable for thermoforming, infrared and curing ovens and paint booths. It has an RS-485 interface that allows up to 32 sensors to be networked on two wires, and user-selectable 0/4-20 mA, 0-5 V, J or K thermocouple outputs. Raytek; 800/866-5478; www.Raytek.com
Increase Sensitivity
Sensing ranges for M12 extended range inductive sensors are 4 mm flush mount and 8 mm non-flush mount. Sensing ranges for M18 are 8 mm and 14mm, and 15 mm and 22 mm for M30. The sensors have 10-40 VDC supply range, and are available in both two and three-wire versions. Outputs are transistor types, with NPN and PNP versions available. The housings are made of nickel-plated brass, allowing the sensors to be both robust and economical. Carlo Gavazzi; 847/465-6100; www.gavazzionline.com
Doesn't Drift
Infosense temperature sensors use software to reduce process variation and drift of thermocouples and RTDs. Each sensor has four error values, known from calibration, printed on small tags. Users simply enter the values into a compatible controller's standard menu. Entering the codes immediately improves sensor accuracy by a factor of two. Other sensors in the product line have an EEPROM with additional information or use IEEE P1451.4 smart sensor technology. Watlow; 314/878-4600; www.watlow.com
Molded Connectors Suit Sensors
M8 and M12 molded connectors have a mechanical safeguard against vibration, gold-plated contacts and IP67 protection, and are available with variable lengths of wire or cables. The M8 and M12 sensor cables come in straight and angled versions, each with male and female contacts in three, four or five positions. The M8 connectors are available in three and four positions. The female connectors are available with or without LEDs. Phoenix Contact; 800/322-3225; www.phoenixcon.com
