How often should the sensors be replaced?

The Toxic sensors should last about 2 years, except the ammonia NH3 sensor which lasts 300 ppm hours and the hydrogen cyanide HCN sensor which lasts 400 ppm hours. The combustible or LEL sensor can last many years. The sensors will need to be replaced when they no longer respond properly to calibration gas.

How often should the user calibrate the monitors?

The user should calibrate or do a functional test, which means apply a known concentration of calibration gas and be sure the sensors respond properly. YES, the user will have to purchase calibration gas. NO, they don’t have to purchase it from Quest Technologies

I put a new sensor in the gas monitor and it won’t zero or calibrate and it’s in alarm or reading negative why?

All sensors except the LEL sensors must be in the unit with good batteries for a stabilization period before calibration and using the sensor. NH3, EtO, and NO may require up to 3 days to stabilize, 24 hours minimum. O2 and the other toxics will require 24 hours to completely stabilize. The unit needs to have a charged battery pack or good alkaline batteries for the sensors to stabilize. The unit does not need to be turned on; the sensors will draw a small amount of current even when the unit is in the OFF mode.

The NiCad or NiMH battery charger is indicating that the charge is complete, but the battery pack is only partially charged; why?

If there are interruptions to the power supply to the charger, or if the voltage to the charger drops below 90V even temporarily, the charger resets itself to a \Charge Complete\ mode. If this is happening you will need a regulating switching supply from Quest which will constantly output the necessary voltage even if the input voltage drops below 90V (part numbers 060-095 Line Cord and 054-721 Power Supply).

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