ORP readings are measured in mV and range from -2000 mV to 2000 mV. Values above zero indicate an oxidizing substance while values below zero indicate a reducing substance. Values do not indicate the concentration but rather the potential of the substance to oxidize or reduce.

Chemicals like chlorine, bromine, and ozone are all oxidizers. It is their ability to oxidize - to "steal" electrons from other substances - that makes them good sanitizers because in altering the chemical makeup of unwanted substances, they render those substances inert. Of course, in the process of oxidizing they use up their ability to further oxidize things. Another common misconception is trying to relate ORP to cellular voltage. 14Some have claimed that because cells have a negative voltage, drinking negative ORP water is healthy. 14However, these two voltages are very distinct from each other and do not relate under biological conditions. Cells have their voltage due to differences in ion gradients and carboxylate moieties from proteins and fatty acids. 15 When you add chlorine to a pool, the chlorine gives up its own electron surplus to neutralize or oxidize potentially harmful bacteria. Active chlorine electrons increase the ORP level of the water, thus neutralizing contaminants. For chlorinated pools and spas, a safe ORP reading is usually between 650 millivolts (mV) and 750 mV. As time passes and chlorine breaks down and loses its oxidation potential, the overall ORP reading for the water gradually decreases. Although ORP levels typically correlate with the ratio of sanitizer in the water, ORP does not measure sanitizer levels; rather, it measures the net oxidation and reduction properties of all agents present. The ORP electrodes are designed to 0mV reading that is null reading at 7pH. As the pH value deflects over or below 7, the deflection in ORP is seen. The extreme range of ORP meter reading remains between -1500mV to1500mV.Now that the introduction, working, and applications of ORP probes are discussed, it is essential to know that the quality of the ORP meter also impacts the results. Therefore, one must buy from trusted suppliers like

AOKI, K., NAKAO, A., ADACHI, T., MATSUI, Y. & MIYAKAWA, S. (2012). Pilot study: Effects of drinking hydrogen-rich water on muscle fatigue caused by acute exercise in elite athletes. Medical Gas Research 2, 12. Automatic or manual temperature compensation - pH sensors incorporate a built-in temperature sensor.

Resources

For use when measuring resistivity boiler and cooling water, lakes, wells etc. Recommended standard - 442-3000 While for most applications ORP measurement is concerned with oxidizers for their sanitizing effect, there has been increasing interest with reducers. Free radicals are atoms and/or molecules with an unpaired electron. Introduced to our bodies as byproducts of biochemical reactions and from the air we breathe and food we eat, free radicals are unstable and desire balance so they try pull electrons (oxidize) from wherever they can. In acquiring balance for itself, the free radical damages other biological molecules in the body. Reducers, also known as antioxidants, donate the electrons sought by free radicals thus minimizing the degenerative effects of free radicals on the body.

Basically *you have different chemical species in the water that can either undergo oxidation or reduction; these form “redox couples”. 3For example, adding ascorbic acid (vitamin C) to water gives a negative ORP 4based on the ratio of reduced ascorbic (HA) acid to oxidized ascorbic acid (DHA) according to the Nernst equation. 5 pH and ORP are important parameters of water quality and a wide range of process applications depend upon the ability to measure and control each. In simplest terms, both pH and ORP represent types of ion activity in liquids—pH measures hydrogen ion activity while ORP represents the potential transfer of electrons between chemicals or chemical compounds. Though measuring very different things, both pH and ORP share a close relationship and are often included together while discussing water quality. The ORP meters are the devices designed for the measurement of the oxidation-reduction potential of water. ORP meters are also industrially known as a redox probe. These chemical or microbial species form redox couple, which results in electron loss. The ORP meters measure the number of electrons lost as a merit of the redox potential of the water. pH stands for "potential of hydrogen" and is a measure of hydrogen ion concentration. A high concentration of hydrogen ions results in acidity while a low concentration results in alkalinity. The concentration of hydrogen ions is represented on a scale from 0 to 14 with 7 being neutral (i.e. an equal number of hydrogen (+) ions and hydroxide (-) ions to cancel each other out). Values below pH 7 are acidic and values above pH 7 are alkaline. The scale is logarithmic, meaning each full point increases or decreases by a factor of 10x. Some extreme substances can score lower than 0 or greater than 14, but most fall within the scale.

At a glance, an ORP electrode looks similar to a pH electrode. Like a combination pH electrode, both the sensor and the reference are housed in a common body. An ORP sensor must be chemically inert; it cannot be oxidized or reduced itself. It must also have the proper surface characteristics to promote rapid electron exchange, a property known as high exchange current density. Two noble metals have proven to work well for this purpose: pure platinum and pure gold are both used in the construction of ORP sensors. Calibration - up to a five-point calibration with seven standard buffers and five custom buffers available. Accuracy of pH measurements is dependent upon well maintained and properly calibrated instruments. The main factors that degrade the performance of an electrode are coating, contamination and aging. Necessary maintenance and calibration depends on these factors and, of course, of the accuracy required from measurements. For more information about how to interpret ORP readings and use ORP meters, research your chosen ORP meters and its unique features. You can make the ORP negative by decreasing the H +concentration (raising the pH) and/or increasing the dissolved molecular hydrogen concentration. Conversely, you can make the ORP positive by increasing the H +concentration (lowering the pH) and/or decreasing the dissolved molecular hydrogen concentration. Important Considerations

ORP is the acronym for "Oxidizing-Reduction Potential" which is the activity of oxidizers and reducers in relation to their concentration. Oxidizers are chemicals and chemical compounds that accept electrons from other substances while reducers donate electrons. ORP is especially important when discussing water quality as it's most notable feature is its ability to measure the oxidation of contaminants. The HI-98190 combines all of the features of a benchtop into a portable IP67 rated waterproof enclosure making them one of the most versatile meters on the market. In alkaline ionized water, the ORP ranges from -100 mV to – 900 mV. 7 The chemical species responsible for the negative ORP is the redox couple molecular hydrogen (H 2) and the acid ( H +) concentration. This is according to the standard redox half-reaction: Tyler LeBaron. (2013 ) “Changes in Oxidation-Reduction Potential of Aqueous Solutions as a Function of pH and Hydrogen Gas Concentration” The Journal of Kitchen Chemistry 2013. 1. P.12 These important points underscore the importance of actually measuring the molecular hydrogen concentration and making comparisons between hydrogen-water devices based off H 2concentrations, as opposed to pH and ORP alone. ORP Misconceptions

An ORP system does not have a high impedance source (like a pH bulb), but is a potentiometric device that produces a voltage. It also uses similar cables, connectors, and calibration solutions. For this reason, a high impedance electronic meter (pH) with many user-friendly features are a benefit for this measurement.