Temperature Sensors in Process Applications

Temperature sensors provide some input to a system that can then determine the temperatures of locations, or physical processes. Usually in order to do this, the sensor must be connected to that system in some way – using a long cable, or via Wi-Fi or other wireless connections for example.

Sensors with extended length cables work fine until the sensor itself needs to be removed for calibration, maintenance, or simply wholesale replacement. This usually entails disentangling the cable from a cable tray or bundle – at the cost of considerable time, labour, and some frustration. Omega gets around this by using extension cables that are connected to the sensor at the point of use; you can then simply detach and reattach the sensor from its cable when required. Wireless networks can be great; but everyone will have had trouble getting Wi-Fi to work reliably with devices, and in some locations or for some applications it might be inappropriate or impossible to use.

Extension cable connected to the sensor

Extension cable connected to the sensor

Learn More About M12 Temperature Sensors

For many years, if you wanted high reliability for your temperature sensors – in an aerospace or military context, say – you’d be reliant on connectors like the Mil-C-5015 or MIL-C-38999 connectors. These connectors were highly reliable and secure, but the cost has meant that they are not an option for everyone – especially as automated systems in industry drive an ever-expanding number of temperature sensors to be used. Omega saw a gap in the market for reliable, secure, and cost-effective connectors.

This led to the development and release of IEC Standard 61076-2-101, “Connectors for Electronic Equipment.” Now, one of the industry standards is an “M12” connector, used across many sensing and control applications and considered reliable, cost-effective and robust.

“M12” connector

Omega Engineering is now leading the way in adapting this new connector system to a variety of temperature sensitive products. Examples include Thermocouples, Resistance Temperature Detectors (RTDs) and Thermistor sensors, as well as cryogenic diode sensors. The number of applications – from food and dairy processing and biomedical applications, through to industry, defence and aerospace – is only continuing to grow.

“plug” style connector

Usually, the exposed connection pins of the connector are on the non-powered side of the connection – i.e. the sensor side, which is hooked up to the power supply via the insulating cable. This prevents unintended contact of the metal pins with the operating current; Omega achieves this using a “plug” style connector. The extension cable provides the operating current, returns the sensor’s signal to the instrument, and has a plug connector. Mechanically-assembled or moulded connectors can be used.

As well as being easier to install and maintain, you can use M12 connectors in wet or wash-down environments due to the sealed nature of the connections. This is particularly useful in the food, dairy and pharmaceutical industries, where you don’t want to worry about electricity when you’re washing-down the temperature sensors; and the M12 connector will also protect the wire from attack and corrosion by cleaning chemicals.

A variety of different M12 connectors can be purchased in many different configurations, but Omega uses the A-coded four-pin connector style for its sensorts. This is because all of Omega’s M12 enabled RTD sensors are made with four-wire construction; they can be used with 2, 3, or 4 wire systems, providing the greatest flexibility for customers. In addition, the thermocouples can be used with single or dual junctions.

Omega Engineering’s family of M12 enabled sensors can be purchased with either machined stainless steel or injection molded housings. The machined stainless steel housings can be supplied with mounting threads, or non-threaded housings, depending on the situation and use case for the sensors. You can also purchase a range of 3A approved tri-grip sensors from Omega. These are designed for Clean-In-Place (CIP) applications, such as food, dairy, and pharmaceuticals.

M12

Omega wants to provide measurement solutions for all kinds of customer applications; so it offers a wide selection of M12 extension cables and accessories to go with its thermistors and thermocouples. This includes the classic PVC and Polyurethane cables as well as fully-compensated thermocyple cables. Mechanically assembled connectors allow you to hook up a wide range of cable constructions and enhancements – like steel overbraid, square locked hoses, and improved mechanical protection or electrical sheilding – to your cables.

M12 extensions cables and acessories

Sensor Type Mounting Style Housing Style Model Number Series
RTD (Pt10 or Pt1000) Non-Threaded Machined SST PR-21A, PR-26A
1/2NPT PR-21B, PR-26B
3/8NPT PR-21C, PR-26C
1/4NPT PR-21D, PR-26D
M8x1 PR-21E, PR-26E
M10x1 PR-21F, PR-26F
G1/2 BSPP PR-21G, PR-26G
G1/4 BSPP PR-21H, PR-26H
Thermocouple (Types J and K) Non-Threaded Machined SST M12…-A
1/2NPT M12…-B
3/8NPT M12…-C
1/4NPT M12…-D
M8x1 M12…-E
M10x1 M12…-F
G1/2 M12…-G
G1/4 M12…-H
RTD (Pt100 or Pt1000) Non-Threaded Molded Nylon PR-22, PR-31
Thermocouple (Type J or K) Non-Threaded Molded Nylon M12M…
RTD (Pt100) Tri-Clamp Machined SST PRS-S-M12
Thermocouple (Types J and K) Tri-Clamp Machined SST TCS-S-M12
Thermistor Tri-Clamp Machined SST THS-S-M12

 

M12 Cables and Accessories for use with the above sensors include the following:

Accessory Model Number Description
Extension Cable M12CM-EXTP-… Fully Compensated M12 Thermocouple cables with PVC insulated cables and TPU over molded connectors (85 °C Max)
Extension Cable M12CM-EXTT-… Fully Compensated M12 Thermocouple cables with Teflon insulated cables and LCP over molded connectors (250 °C Max)
Extension Cable M12CM-EXTT-4-… 4-Wire M12 Teflon extension cable with LCP over molded connectors for RTDs and other process sensors
Extension Cable M12C-PUR Polyurethane cable with Molded M12 connector one end or both ends
Extension Cable M12C-PVC PVC cable with molded M12 connector one or both ends
Special Extension Cable M12CFM- Extension cables with mechanically assembled M12 connector one or both ends, variety of cable materials as well as steel braiding or hose options
Field Mountable Connectors M12- Field installable connectors, straight or right angled, plug or socket style
Spring Loading Kit for Thermowells ¼-SLK Allows ¼” probes to be spring loaded into .260 bore, ½” NPT or NPSM threaded thermowells
Spring Loaded 1/2x1/2 SLF-1/2-1/2-1/4 Allows ¼” probes to be spring loaded into .260 bore, 1/2NPT or NPSM threaded thermowells with 1/2NPT thread for attaching enclosure
Stainless Steel Compression Fitting SSLK Stainless Steel fixed location compression fitting
Brass Compression Fitting BRLK Brass fixed location compression fitting

 

This information has been sourced, reviewed and adapted from materials provided by OMEGA Engineering Ltd.

For more information on this source, please visit OMEGA Engineering Ltd.

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