Which is good for gas sensing testing of metal oxide.
Can 5 and 1/2 digital multimeter is sufficient for testing
or do we need higher resolution digital multimeter.
If so which company is good for this purpose.
Can someone name model number and company name
Vijayarangamuthu,
It depends on what sensor you are reading.
If your gas sensor delivers a 10V swing from 0V in a change from 0 to 100% of the gas of interest, and you demand only 1% accuracy, then you need only +-100mV of accuracy.
If your gas sensor delivers a 1 millivolt swing, from 0 to 100%, then you'll need a better meter. Or a stable amplifier.
We do not have enough information to make a suggestion for you - please advise.
In a common case (the sensor response is from 0 to 10....) you have to verify, in this order, that:
- at least one of the measuring ranges of the instrument covers the measured values range (sensitivity criterion)
- the input impedance of the instrument is high enough to be compatible with the impedance/resistance of the sensor/measuring circuit (impedance compatibility criterion); a "basic" instrument may fail this criterion,
- the resolution/readability of the instrument is the observed response precision of the sensor (consider here the relative standard deviation of the recordings) plus 1 digit (resolution criterion). For a common case, 5 1/2 digits is too much ( if the sensor precision is 1%, a 3 digits instrument is enough).
The difficult case is when you have to measure a small variation Δx of a high value X. The best solution is to use a differential measurement (in this case you will also measure from 0 to 10....); if this is not possible, a very high resolution (many digits) instrument is needed.
Dear Vijayarangamuthu Kalimuthu ,
Actually i agree with Cornel Radu and James Garry, but i have to suggest that it depends on the per-amplification and processing stage of your sensing unit it that will give you better view for your sensing unit.
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