An infrared thermometer measures the thermal radiation emitted by an object without requiring contact.

Unlike the PosiTector DPM IR, the PosiTector IRT measures surface temperature only. The PosiTector DPM family measures a number of climatic parameters including relative humidity, air temperature and surface temperature allowing it to calculate dew point temperature and the all-important difference between surface temperature and dew point temperature (Ts-Td) - a vital parameter for industrial painters.

The PosiTector IRT has a larger distance to spot ratio and a button activated laser pointer for precise and accurate surface temperature measurement.

The distance to spot ratio refers to the relationship between the diameter of the area being measured compared to the instrument’s distance from that area. As the distance (D) from the measured surface increases, the spot size (S) of the area being measured becomes larger.

The D:S ratio of the PosiTector IRT is 5.7:1. For example, when the instrument is 85 cm (34 inches) from the surface, the spot size will be 15 cm (6 inches) in diameter. The temperature reported will be an average of the temperatures contained within the spot size. The greater the spot size, the more information will be gathered and averaged, giving you a better estimate of the area’s true temperature. A lower D:S ratio is advantageous when measuring large areas.

Emissivity refers to a material’s ability to emit infrared energy, compared to an ideal black surface at the same temperature. The PosiTector IRT has built-in emissivity settings for certain materials as well as user-adjustable emissivity options. Select from a list of preset emissivity options, manually adjust the emissivity value or adjust to a known temperature.

Most organic and painted surfaces have an emissivity of around 0.95. Shiny or reflective surfaces can be difficult to measure with an infrared thermometer, as they tend to reflect ambient infrared energy instead of emitting their own. To compensate for this, cover such surfaces with flat paint or a piece of electrical tape. Allow the paint or tape to acclimate to the surface’s temperature and take a measurement over the paint or tape.

Yes, but adjusting the emissivity setting is critical. Depending on surface treatment, metals such as blasted steel can have a broad range of emissivity values. Adjusting to a known temperature (measured by a direct contact surface temperature probe) on a representative sample will assist in obtaining an accurate emissivity value. Some blasted surfaces can reflect nearby sources of infrared energy, impacting results. DeFelsko recommends situational testing be done to determine accuracy.

An infrared surface temperature probe measures surface temperature from a distance without contacting the surface. An IR surface temperature thermometer is useful for measuring temperatures in areas where conventional sensors will not work including hard to reach areas and moving parts. Also ideal for measuring on objects whose temperature is above the recommended range for direct contact sensors or when contact with a sensor would damage the surface as is the case for freshly sprayed powder.

The 5.7:1 distance to spot ratio of the PosiTector IRT will average the temperature over a larger area and is ideal for quickly scanning large steel structures.