The ACI Platinum Strap-On Series features a 1.5?Ç¥ square copper plate with the sensor encapsulated to the back side of the copper plate to improve the thermal conductivity between the pipe and sensor. Each sensor has Etched Teflon colored lead wires to differentiate the different sensor types. The three-wire ?Ç£-3W?Ç¥ option should be ordered when using with a 3-Wire temperature transmitter or sensor configuration on your building management system or PLC [Programmable Logic Controller]. The purpose of the 3rd wire is to compensate for any external lead wire resistance that will affect your sensors output signal. ACI recommends the use of 18 AWG lead wires to reduce the external lead wire resistance when using a Platinum RTD sensor. Sensors in this series are manufactured using ACI?ÇÖs proven double encapsulation process to eliminate the effects of moisture on the sensor as well as to improve thermal response times with our high quality, thermally conductive epoxy. Strap-On sensors can be used to monitor pipe sizes from 1 ???Ç¥ to 10?Ç¥ in diameter. ACI recommends to clean the pipe before applying thermal grease and installing the sensor before finally insulating the sensor from the effects of the ambient air. Optional Weather Proof enclosures and NIST Certificates are available as referenced on the back of the Product Data Sheet.