It has been almost three years since Industrial Scientific launched the AskDave portion of our website. In the nearly 2000 questions I have answered since the beginning, there is one that stands out by far as the most frequently asked. Why is there no oxygen sensor showing up in my M40 display?
So, just what does happen to that oxygen sensor reading anyway?
The galvanic fuel cell oxygen sensor, like that used in the M40 and other similar instruments, is one of the only sensors that normally produces a signal larger than its baseline output in a clean air environment. The M40 and other instruments that do not use “smart sensor” technology rely on that signal to identify that the oxygen sensor is in place and properly installed in the instrument. When the sensor reaches the end of its useful life, it no longer has any measureable output at all and therefore it has no way to identify itself to the instrument when the unit is turned on. The end result is that the oxygen sensor disappears from the instrument display, simply because the instrument does not know that it is there.
Do not be alarmed by this condition. The sensor cannot disappear from the instrument during use. Oxygen sensors that lose their output during use will fail to a condition that puts the instrument in a continuous high alarm state and will not leave you unprotected.
This is just another in the long list of reasons that you should verify visually that all of your sensor readings appear to be normal each time you turn your gas monitor on and bump test every sensor before use.
Keep those questions coming and above all, keep safe.
Dave
4 comments
Amin Salem says:
February 8, 2012 at 8:10 am (UTC 0)
Dear Sir
what is the effective horizontal/vertical distance for B25 detector
Dave Wagner says:
February 9, 2012 at 2:49 pm (UTC 0)
Amin,
A diffusion based monitor like the BM25 can only detect gas that diffuses into the sensors. Therefore it can only detect gas that is in the immediate vicinity of the sensors. Placement of the unit is critical. It essentially has no effective “range” as you say, so it must be placed in a position where gas from any potential source is likely to diffuse toward and into the monitor.
gelbert rettiz says:
May 16, 2012 at 10:34 pm (UTC 0)
buenas tardes sr Dave, quiero saber el precio de un M40-M, y cuanto me constarían 10 unidades completas con su recarga?…., también quiero saber como tengo que hacer para que el producto llegue a Colombia?
gelbert rettiz says:
May 16, 2012 at 11:07 pm (UTC 0)
Buenas Noches, quiero saber el precio del MX4? y del M40-M?