This portable indicator is a convenient and handy instrument for field applications where a quick, easy and accurate measurement of oxygen is required. The sensor is located within the instrument requires the gas sample to be delivered to be inlet port. This instrument is ideal where the sample is available at a slight positive pressure. Alternately, a sampling pump can be provided. It has a wide variety of applications and can be used for Leak Detection, new Cylinder inspection, to handle Emergency response, Equipment maintenance, quality control check, gas emission analysis.