Cold winter temperatures have set in over most of the northern hemisphere and with them come some differences in the way your portable gas monitoring instruments function. The low temperature rating for continuous operation of most Industrial Scientific portable instruments is -20 degrees Celcius. However, they may be used at lower temperatures for intermittent periods. The response of the sensor does change as the temperature gets colder but the response is compensated to cover the effects of the low temperature and keep your gas readings within +/-15% of the actual concentrations.
Here are some tips to help you get a warm feeling from your gas monitors when you are using them in out the cold.
1. When you walk outside, you feel the cold instantly. However, it will take a while for your gas monitor to reach equilibrium with the ambient temperature. The temperature compensation will track with the internal temperature of the monitor. If you are going to be using the monitor for 20 minutes or less, there is no reason to allow it to stabilize and adjust to the temperature before useing it. Turn it on, take your readings and get back inside where it is warm.
2. If you will be using your monitor outside for extended periods longer than 20 minutes, it is best to let it stablize at the ambient temperature for 15 – 20 minutes before use and then turn it on and zero the sensors in fresh air.
3. The response of the instrument will get sluggish at temperatures below -20C. The display may get dim and even go blank if it freezes. If this happens, your gas monitor will likely still detect gas and will still alarm. If you have to use it this way, you should bump test it before each use to make sure it responds and you should get your unit warmed up as soon as possible.
4. The sensors in your instrument will start to freeze at temperatures below -20C for an extended period of time. The oxygen sensor will normally be the first to freeze. When frozen, the sensors will not be able to produce a reliable reading, but functionality should return once they warm up and thaw out.
5, Battery run time will be reduced at low temperatures. Below -20C expect at least a 30- 40 percent reduction in run time.
6. Keeping your gas monitor close to your body will keep it as warm as possible. If you are using the monitor for remote sampling, keeping it inside your coat as long as possible will help keep it warm and functioning longer.
A good rule of thumb for using your gas detector in cold temperatures is that your gas monitor can generally stand to be out and working in the cold as long as you can. If it’s too cold for you, it’s probably too cold for the instrument as well.
Baby it’s cold outside, so until the milder temperatures of spring return, work safe, and try to keep warm.