Insta O2 PPM Sensor – Replaces Teledyne InstaTrace B71875 sensor. AST Model Insta O2 is the only sensor with same form-fit-function as Teledyne Insta Trace O2 sensor, no spacer needed. Proprietary gas impermeable membrane in front of Insta O2 protects sensing cathode from exposure to high level of oxygen in air during installation. During installation, sample gas continues to flow thru sensor housing. After installation, protective membrane is automatically punctured inside of sensor housing and the sensing surface sees nothing but O2 in the sample gas. This speeds up sensor’s recovery and sensor stabilizes with actual oxygen in sample gas in just a few minutes. Insta O2 is ideal for measuring oxygen in inert and gaseous hydrocarbon streams. AST Insta O2 is designed, developed and manufactured in the USA.