On this page we explain how to use your IRt/c or AutoSmart IRt/c optimally. You will find information about
- Installation instructions and manuals for the IRt/c, AutoSmart IRt/c and Novus PID controller,
- sensor readout, dealing with the IRt/c’s high impedance
- what parameters to consider when selecting an IRt/c.
Should you have any other questions about the use of our sensors, please contact us at firstname.lastname@example.org
All infrared-based sensing systems must be calibrated for specific material surface properties (for example, the amount of heat radiated from the target surface, environmental heat reflections, etc.). This calibration is performed by measuring the target surface temperature with a reliable independent surface temperature probe. The easiest and fastest method of accurately calibrating out these effects is to use an Exergen Microscanner D-Series hand-held Infrared Thermometer with a patented Automatic Emissivity Compensation System, which gives a true reading regardless of emissivity. Your Authorized IRt/c Distributor will be pleased to make a D-Series available for your installation. To calibrate Adjustable models (IRt/c.xxA) see Tech Note #60.
The following procedure is recommended:
1. Install the AutoSmartIRt/c as close as practical to view the target material to be measured.
2. Wire the AutoSmartIRt/c to the controller, PLC, etc. in standard fashion (see PINOUT and WIRING DIAGRAM)
3. Bring the process up to normal operating temperature and measure the actual temperature of the target material with the Microscanner D-Series, Infrared Thermometer or any other reliable reference.
4. If using a PID controller: adjust “input offset,” “zero”, “low cal,” on the readout device to match the reading of your reference.
5. Installation Complete. (For OEM installations preset the same adjustments. Individual calibration is not required.)
Some thermocouple readout devices produce leakage currents which can create offsets when using an IRt/c. The current originates from two sources within the device: leakage current actually generated by the input amplifier, and leakage current intentionally injected to the thermocouple circuit to detect an open circuit due to wire breaks.
These currents are normally of no consequence with conventional thermocouples with resistances < 100 ohms. However, with the higher resistance of the IRt/c (~ 3 Kohms), devices with high currents will create offsets.
For many OEM and general temperature control applications it is sometimes desirable to test sensors before being placed into service, or to conduct routine checking while they are in service. Accordingly, recommended procedures are presented to allow easy checking with commonly available equipment. However, prior to testing, it is important to understand what indications an actual IRt/c failure might cause.
To select a model for an application, answer the following five points in order. You should then be in a position to select the optimum sensor.
1. Type of Controller / Transmitter / Input Most sensors are available in J, K, E or T types. The thermocouple type should be the same as the readout/controller input type.
2. Target Material Virtually all non-metal surfaces are good emitters and work well with IRt/c sensors (Tech Note #31). If a target is to be viewed and it cannot be coated or an uncoated metal masked, a LoE model must be selected (Tech Note #21).
3. Target Temperature Exergen offers 8 pre-calibrated temperature ranges for convenience (Tech Note #49). The sensors can be used outside their calibrated ranges, up to the temperature limit; with stated repeatability: 550°F limit: IRt/c.01 and IRt/c.03 1200°F limit: IRt/c, IRt/c.1X, IRt/c.3X, IRt/c.5 and IRt/c.10
4. Target Size and Distance Between Sensor and Target The target should completely fill the field of view (Tech Note #55). As an example, the IRt/c.3X has a 3:1 field of view, this means that at a distance of 24” from the target the sensor will view a 8” diameter spot (spot size = distance ÷ 3). All of the IRt/c sensors have a minimum spot size (this minimum spot size varies with model type). It is not recommended that a sensor be used with a target smaller than the minimum spot size. Based on the minimum spot size: For a target <0.3” (8mm), select a focused unit For a target 0.3-0.8” (8-20mm), select IRt/c, IRt/c.01, IRt/c.03, IRt/c.1X or IRt/c.3X For a target >0.8” (20mm), select any sensor.
5. Ambient Temperature and Environment The IRt/c.01 and IRt/c.03 can be used in ambient temperatures up to 160°F (70°C). All of the other sensors can be used in ambient temperatures up to 212°F (100°C) without any external cooling. Above 212°F the IRt/c can be used with the CJK-1 cooling jacket and the IRt/c.3X can be used with the CJK-2 cooling jacket (see accessories). The IRt/c.5, IRt/c.10 and all of the adjustable sensors have a built in air purge that can be used to cool to ambient temperatures up to 450°F (230°C). If the environment where the sensor is placed is prone to be dusty or otherwise dirty, it is good practice to select a sensor with an air purge. If linearization software can be employed in the readout device, HiE and LoE models can be supplied in a pre-calibrated form (see Tech Note #96). This allows for the convenience of a precalibrated range and security from accidental sensor adjustment after installation.
The Heat Balance (HB) Series of IRt/c infrared thermocouples have the ability to measure the internal temperature of the target material, non-invasively, by employing a patented heat balance technique. A typical application in medical equipment is monitoring or controlling the temperature of fluid transported through disposable tubing when warming or cooling.