Effect of residual flux on a strain gauge (Gage Installation Tester)

Two of the most important measurements used to verify the quality of a strain gage installation are insulation resistance (leakage to ground) and shift in gage resistance due to installation procedures. While these two measurements are not a complete guarantee of eventual proper strain gage performance, any installation that produces questionable values should not be relied upon where accuracy of results is necessary.
Insulation resistance in excess of 20,000 megohms should be expected for foil strain gages when installed under laboratory conditions. A value of 10,000 megohms should be considered minimum. A reading below this value generally indicates trapped foreign matter, moisture, residual flux or backing damage due to soldering, as well as incomplete solvent evaporation from an overcoating.
The 1300 Gage Installation Tester is used to verify the quality of an installed strain gage , as well as the complete gage installation, including leadwires. A carefully selected individualized test voltage is used for each measurement mode. Operation is by push buttons.
Features
• Compact size
• Battery operated convenience
• Reads insulation resistance to 20 000 megohms
• Measures deviation of installed gage resistance to 0.02%
• Ohmmeter scale available for troubleshooting
• Verifies the complete installation, including leadwires

M-LINE Rosin Solvent: