Acidic error occurs in strong acid solutions where the decrease of H+ activity leads to a higher pH reading than the real value (usually happens when pH is less than 1). Strong acidic solutions also corrode pH glass membranes. Hydrofluoric acid solution is extremely corrosive and could directly dissolve conventional pH glass membranes. 

The HF glass membrane of LabSen 831 and 833 is corrosion-resistant and can measure solutions containing HF acid for up to 1000 times at the condition where measurement time is less than 60 seconds and HF concentration is less than 0.1 mol/L or 0.2 wt%. It is also suitable for solutions containing HCl and H2SO4. Compared with conventional electrodes, the service life of LabSen HF electrodes is significantly increased.