ORP (Oxidation Reduction Potential) electrodes are used to measure a chemical reaction in which one species is being oxidized and another is being reduced. The loss of electrons by an element or compound is known as oxidation reaction while the gaining of electrons by an element or compound is known as reduction reaction. For example, plating companies that have hexavalent chromium (Cr6+) in their wastewater must reduce it to a safer trivalent chromium (Cr3+) form. This reduction reaction occurs in the presence of a strong reductant such as sodium metabisulfite. The addition of the reductant must be measured with an ORP electrode to ensure that there is an adequate reducing potential. Using the HI7091L reducing pretreatment solution prior to taking a measurement provides for a faster response time in a reducing environment.
To use, soak the ORP electrode in the pretreatment solution for 15 minutes prior to use. As a general rule, if the mV reading corresponding to the pH measurement is lower than the value in the table below the reducing pretreatment solution (HI7091) is used. If the mV reading corresponding to the pH measurement is higher than the value in the table below then the oxidizing pretreatment (HI7092) should be used.
| pH Value | mV Value | pH Value | mV Value | pH Value | mV Value | pH Value | mV Value | pH Value | mV Value |
| 0 | 990 | 3 | 800 | 6 | 640 | 9 | 460 | 12 | 280 |
| 1 | 920 | 4 | 740 | 7 | 580 | 10 | 400 | 13 | 220 |
| 2 | 860 | 5 | 680 | 8 | 520 | 11 | 340 | 14 | 160 |
The HI7091 bottle is labeled with
- Product code
- Lot number
- Expiration date
Airtight bottle with a tamper-proof seal
- Ensures quality and freshness of solution
