Affect of elevation on ASTM C231.

[Eapnat]

My air meter was calibrated at roughly 4000 feet of elevation and it is not uncommon for us to be testing concrete 1000 or 2000 feet higher. I have noticed discrepancies when testing air content at these higher altitudes. On the face of it, it does seam that there could be an affect. The question is, how much and what do I do about it?

Is there a conversion, or should I re-calibrate for each elevation?

Thanks for the help.

 

[Ron]

Switch to the volumetric method (C173). The pressure method is susceptible to atmospheric variances.