ORP standard solutions allow you to test the precision of ORP electrodes. For example, by immersing the electrode in HI 7022 solution, you should read 470 mV @ 25°C/77°F
If the reading is outside the indicated interval, clean and condition your ORP electrode in HANNA® pretreatment solution. Use HI 7092 for oxidizing or HI 7091 for reducing pretreatment.
HI98120 ORP/°C-Tester, waterproof
HI7010L - 10.01 pH@25°C - SQ - 500ml
HI7609829-4 - Conductivity / Turbidity Sensor for HI9829 Multiparameter
HI4104 - Calcium ISE, Polymer membrane combination 

