Sensor requires no support gases and can be easily and accurately calibrated using compressed air within 30sec. on an annual basis.
Also included in this package are 2 factory preset Caution (20.0%) and Danger (19.5%) oxygen concentration alarm relays, a 90db audible beeper set for 19.5%, battery backupand an internal circulation fan that helps move stationary room air.
The Model 221 is a compact, rugged, RFI proof oxygen analyzer utilizing state-of-the-art analog basedelectronics with a large 3½ digit LCD. UL approved.