Can you use a refractometer to measure DEF Quantity? Is it acceptable practice to add water to adjust over-concentrated samples?
The Palm Abbe digital refractometer (DEF201 or DEF202) can be used to very accurately measure urea concentration in DEF to +/-0.1%. DEF is a composition of ultra-pure urea and demineralized water. ISO standards call for DEF to be 32.5% (+/-0.8%). If your DEF is over-concentrated, due to evaporation, you can add demineralized water to return the measurement to 32.5%. However, you should NEVER add tap water or well water to a DEF. Doing so can cause irreparable damage to your SCR components.