GB/T 27756-2011 standard specifies the classification, technical requirements, test methods and inspection rules of Glass electrodes for the determination of pH value of aqueous solutions. The standard covers the requirements of laboratory type and online type electrodes, which are divided into two categories: normal temperature type and high temperature type to adapt to different use environments. Specifies the performance indicators of electrodes, including zero pH value, Response time, internal resistance, etc., and provides detailed test methods and conditions. The standard also specifies the Encasement, transportation and storage of Counter electrodes to ensure the accuracy of electrode performance and measurement results in actual use.