The Hand-Held Purge Monitor (HPM) is a robust unit for measuring oxygen levels while purging. It is convenient to see when welding can commence when the display changes colour based on the user’s upper and lower oxygen levels. Depending on your budget and resolution needs, we offer two models. With the HPM-01, oxygen levels are displayed accurately up to 100ppm using a simple non-depleting optical oxygen cell. Combining HPM-01 technology with a miniature, low-power Zirconia sensor, the HPM-02 displays Oxygen levels to 1ppm.