How to choose active infrared beams
There are different beams quantity such as 2 beams, 3 beams, 4 beams, 6 beams and 8 beams of photoelectric beam sensor. So, how many beams should I choose? The more beams means higher of protection height and longer of detection distance. For example, if the distance between two infrared holes is 35mm, then, for 3 beams sensor, the protection height is 70mm. For 4 beams sensor, any two neighbor beams are blocked, it will trigger alarm. Same for 6 beams or 8 beams sensor. So more beams will be with more security such as for bank. More beams means more power of infrared beam transmission and with stronger penetration to against interference of fog, sunshine etc.
And what does the infrared detection distance mean? It means the distance between the transmission terminal and receiving terminal. The actual installation distance should be less than 80% of the specified distance. For example, the specified detection distance is 100m, then the actual installation detection distance should be less than 80m. If no interference, the detection can reach to 6 times of specified distance. (6*100=600m). But environment interference should be considered for using.
There are some rules for active infrared beam installation. For example, if the beam sensor is installed on a low wall, the distance between the top of the wall and the lowest infrared hole should be around 150mm. Because the size of a normal person is 500mm(width)*200mm(thickness), that will avoid intrusion of people from bottom side of the beam sensor and false alarm triggered by small animals.