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Much better than its looks: not well described by manual
on August 20, 2011
This IR thermometer seems to use similar modules as more expensive brands. It could be a copy or an OEM version of many branded models, its commonly listed as the DT-380 or DT8380 Infrared Thermometer. For $12, its a steal if you know more about how to work it properly, and it works wonderfully.
Digital Thermometer 8:1 distance:spot ratio for 380C decodes the model number.
I tracked a similar looking manual and nearly identical device to a Chinese factory, See comments.
The manual is nearly identical to the model I received. I can't disassemble the unit to check the PCB and makers mark since part of the unit is glued.
IR thermometers are calibrated against dark or black bodies, and perform worst with reflective surfaces like stainless steel, foil, or mirrors. For best results, point to dark to black surfaces.
I tested it as no worse than 10F off, at best 1F, when measuring dark to black bodies, respectively. Its rubber coating makes an easy grip. The trigger has a sharp click, its not soft and gummy. The LCD is easy to see, and the best angle for viewing its LCD is also the best angle for measuring, perpendicular to the measured surface. Beware that when the measured point is fairly close and localized, regional changes in irregular or curves surfaces can happen, like pottery, cups, and mugs.
Using a black mug and pot, I checked IR readings against 32F ice water and 212F boiling water. The temperature was compared against an Agilent thermocouple. The IR reading was 0.5-2F off from the immersed probe. IR reads of a hot Calrod heater was compared against a thermocouple to 900F+, and the IR thermometer read true, far above its rated temperature. It read body temperature 0-2F off compared to a standard oral thermometer!
At extremes changes of ambient temperature, the focusing lens need to acclimatize, the manual recommends 30 minutes. For example, if taken out to a hot summer day of 100F, from 70F air conditioning, the unit may read low. Likewise, from a warm car to the outdoors during winter. This low cost unit uses a Fresnel plastic lens which is prone to thermal deformation more than other lens materials. How much the error is depends on the extent of the difference between one ambient temp and another: if used too soon the IR light may not be optimally focused onto the IR detector.
I am impressed, so I bought another! I've been looking for a good deal on these for years, even Harbor Freight can't match it.
With 2 units now to compare I tested acclimatization, I took one unit to a 73F cold airconditioned room and left one out doors at 85F for 1 hour. Sure, enough, they were off ~3F when they were reading nearly identical earlier. After 1 hour with both units in the same room, they were off from 0-0.5F, awesome!