User manual VAISALA HM34

[. . . ] The humidity and temperature sensors are housed at the tip of an extendable probe, where a semipermeable membrane filter protects the humidity probe against water and dust. [. . . ] Automatic power-off The meter automatically switches off after about 3 minutes, unless a pushbutton is pressed or the meter is set in HOLD mode. Calibration and maintenance of the meter should be performed at regular intervals which depend on the conditions of use and the desired accuracy, but at least once a year. This field calibration can be performed against a calibrated Vaisala humidity meter. for a higher-accuracy two-point calibration use a Vaisala HMK11 calibrator and saturated salt solutions as described in the Operating Manual of the HMK11. The calibration is done first for the dry end and then for the wet end by adjusting trimmer potentiometers "DRY" and "WET" respectively. Replacing the sensors When you replace a defective H-sensor package with a new one, make sure you handle the package with care. If the "WET" trimmer potentiometer has not been adjusted from its factory setting, a one point calibration is sufficient. Chemical tolerance of the humidity sensor (HUMICAP® ) Long-term exposure of the sensor to certain chemicals and gases may shorten its life. [. . . ] WARRANTY Vaisala issues a guarantee for the material and workmanship of this product for one (1) year from the date of delivery. [. . . ]