An air purge is ideal for keeping the lenses of infrared temperature sensing heads in continuous manufacturing duty service clean, especially in particularly dirty or oily environments. Even a small amount of dirt or oil coating on a lens can affect the reading: if 5% of the lens area is covered, then 5% of the reading is lost. For conventional IR devices, with lens size of 1” (2.5 cm) or more, upwards of 1 CFM (.03 cubic meter/min.) is required to maintain cleanliness. At typical costs for plant compressed air, a single continuous duty conventional IR sensor uses approximately $100 of air per year. Clearly, if a plant has many IR installations, the cost of air is of considerable concern.
The small 1/4 inch (.6 cm) lenses of the IRt/c.3x and IRt/c.3SV make it possible to purge with as little as .01 CFM (.0003 cubic meters/min.) of air. With such a small amount of air, it becomes possible to use instrument air, if it is conveniently available, which is already clean and dry, without adding the additional hardware to clean and dry the IR purge air. In addition, the IRt/c.3x can be air purged with a small inexpensive air pump, thus not requiring a plant air source. At the very low flow rate, the IRt/c air cost is only approximately $1 per year, a 100-fold reduction over conventional IR devices.