Calibration Theory

Density Calibration:

Nuclear gauges are calibrated at the factory by establishing a relationship between the counts and known density blocks. Most manufacturers use an exponential equation to model this relationship. InstroTek, CPN, Humboldt and Troxler use an equation similar to CR=Aexp(-BD)+C, where A, B and C are gauge parameters, CR is the count ratio and D is the material density. Each gauge is shipped from the factory with a set of A, B and C values for each depth. Each manufacturer uses a different number of blocks ranging from one to five. Troxler Electronic Labs has used a one block calibration (Method 1) since 1989. InstroTek and CPN international use a three block calibration and Humboldt gauges are calibrated with five block method.

Gauge calibration will change with time due to rugged use, rough construction industry environment, changes to the gauge mechanical geometry and electronic drift of the gauge components.

Gauge users often ask "How often do I need to calibrate my gauge?" The patented, lightweight and rugged ValiDator will allow you to calibrate your gauge at any desired interval. This revolutionary product will verify your calibration or calibrate your gauge. You can also eliminate chances of disputes resulting from density measurements taken by two or more gauges on the same job site. A simple procedure using the ValiDator and ValiDator II (for 4640B Thinlayer) will help you avoid these difficult situations.

Others have tried, but InstroTek is the only company with the know how and the technology to develop this innovative product.

Moisture Calibration:

Moisture calibration is performed in the factory by using counts from blocks of known moisture density. The counts along with the moisture content of these blocks are used in a straight line equation such as CR = E + FM to calculate the intercept E and the slope F. CR (count ratio) is the ratio of counts on the blocks to the standard count.