Appendix G.Model 4150-5 Extended Range Strain Gauge

The Model 4150-5 strain gauge, a modified version of the 4150 gauge, features a range of 10,000 microstrains. Note the following when using the 4150-5:

■The gauge is installed in the same manner as the standard 4150 gauge; however, the position within the range should be set by the user, using the calibration report for each gauge as a guide.

■Push or pull gently on the gauge before spot welding the second tab.

■For maximum accuracy, use polynomial data reduction equations.

■4150-5 gauges are individually calibrated due to the technique used to obtain the required range.

■The thermal coefficient of the gauge is also different from the standard gauge, in that it varies throughout the range of readings. Use the instructions below to make corrections for temperature effects:

When using the Linear Equation:

Strain = G[R₁ – R₀) – K_t(T₁ – T₀)]

Equation 19: Model 4150-5 Temperature Effects

Where:

K = (M*R₁+B) 

M is 0.0002205 

B = –0.03886 

G is the linear gauge factor = 1.0296 microstrain/digit (position B)

R₁ is the current reading

R₀ is the initial reading

T₁ is the temperature of R₁ 

T₀ is the temperature of R₀ 

For example:

If:

R₁ = 6682

R₀ = 6596

T₁ = 30.13C

T₀ = 20.09C

K = [(0.0002205*6682) – 0.03886] = 1.4345 

Then, after temperature correction;

Strain = 1.0296[(6682-6596) +1.4345(30.13-20.09)] =+ 103 microstrains.

When using the Polynomial Equation:

The value of R₁ for temperature must be corrected before using the polynomial equation.

Using the same example as above, the correction to R₁ is K(T₁–T₀) = 1.4345(10.04) = +14.4.

Therefore, if the current value of R₁ is 6682, the value (corrected for temperature) which must be entered into the polynomial equation is 6682+14.4 = 6696.4.