PT Ecological Services Private Limited

Usage/Application	Industrial
Brand	OPRUSS
Type	Glass Electrode Type
Material	SS316 POM
Accuracy	+1%
Model Name/Number	OPM pH Sensor
Output Type	RS485
Temperature Range	2-55 Degree C

Minimum order quantity: 1 Unit

pH & Temperature Sensor

pH is a measure of the acidity or alkalinity of a fluid. The pH of any fluid is the measure of its hydrogen ion (H⁺) concentration relative to that of a given standard solution. The pH may range from 0 to 14, where 0 is most acid, 14 most basic, and 7 is neutral.

pH stands for the “power of hydrogen”. The numerical value of pH is determined by the molar concentration of hydrogen ions (H+). This is done by taking the negative logarithm of the H+ concentration (-log(H+)). For example, if a solution has a H+ concentration of 10^-3 M, the pH of the solution will be -log(10^-3), which equals 3.

Acids and Bases

Acids and bases can cancel each other out because an acid releases a hydrogen ion or proton (equivalent to H+) and a base accepts a hydrogen ion or proton. In other words, an acid is a substance that will decrease pH when added to pure water. In the same manner, a base is a substance that will increase the pH of water. To further define these substances, Arrhenius determined in 1884 that an acid will release a hydrogen ion (H+) as it dissolves in water, and a base will release a hydroxyl ion (OH-) in water.

Factors affecting pH of water

There are many factors that can affect pH in water, both natural and man-made.

1. Pollution

Anthropogenic causes of pH fluctuations are usually related to pollution. Acid rain is one of the best known examples of human influence on the pH of water. Any form of precipitation with a pH level less than 5.0 is known as acid rain. This precipitation comes from the reaction of water with nitrogen oxides, sulfur oxides and other acidic compounds, lowering its already slightly acidic pH. These emissions usually come from mining and smelting operations or fossil fuel combustion (coal burning and automobiles). Extremely high levels of CO2 can also further decrease the pH of rain.

Point source pollution is a common cause that can increase or decrease pH depending on the chemicals involved. These chemicals can come from agricultural runoff, wastewater discharge or industrial runoff. Mining operations especially coal produce acid runoff and acidic groundwater seepage if the surrounding soil is poorly buffered. Wastewater discharge that contains detergents and soap-based products can cause a water source to become too basic.

2. Carbonates

Carbonate materials and limestone are two elements that can cause pH changes in water. Calcium carbonate (CaCO3) and other bicarbonates can combine with both hydrogen and hydroxyl ions to neutralize pH. When carbonate minerals are present in the soil, the buffering capacity of water is increased, keeping the pH of water close to neutral even when acids or bases are added. Additional carbonate materials beyond this can make neutral water slightly basic. The pH of rain can also be lowered due to volcanic ash, sulfate-reducing bacteria in wetlands, airborne particulates from wildfires and even lightning. If rain falls on a poorly buffered water source, it can decrease the pH of nearby water through runoff.

3. Carbon dioxide

Carbon dioxide is the most common cause of acidity in water. Photosynthesis, respiration and decomposition all contribute to pH fluctuations due to their influences on CO2 levels. Carbon dioxide exists in water in a dissolved state just like oxygen; it can also react with water to form carbonic acid.

pH Limits

 

According to the Central Ground Water Board, BIS (IS_10500 and revised module IS 10500:2012) has specifications in Uniform Drinking Water Quality Monitoring Protocol. The acceptable limit for pH is from 6.5 to 8.5.