Chemical metering is used in a number of different industries. Chemicals need to be accurately dosed into the system as specific time intervals to ensure the best results. Chemical metering is commonly used in municipal water treatment and other water and wastewater treatment applications. This process is also used to provide fuel additives in the oil and gas industry, as well as in mining and ore processing to separate precious metals from the rocks and dirt in a wash plant.
It’s important to select a chemical metering pump that is right for your specific application. First, you must understand the chemicals being dosed. Some are much more acidic, corrosive or abrasive than others. You need a pump that can handle the chemical being used and provide the most accurate dosing. For example, common chemicals used in water treatment include sodium hypochlorite, sulfuric acid, sodium hydroxide, sodium bisulfate and emulsion polymers.
All of these chemicals have very different properties and no metering pump is designed to handle them all. Here are some of the unique types of pumps used in chemical metering:
Mechanical Diaphragm Metering Pumps
Mechanically actuated diaphragm pumps are easy to use and install, especially when compared to motor-driven pumps. They are also great at dosing very sensitive chemicals and fluids with the diaphragm design and strong suction-lift capabilities. In addition, mechanical diaphragm metering pumps can handle highly viscous chemicals and liquids that off gas (such as sodium hypochlorite). Repeatable accuracy for these pumps is around +/-2%. On the negative side, these pumps usually have limited discharge pressures (100-150 PSI or 7-10 BAR) and it’s a good idea to add an external relief valve to avoid over-pressurization.
Hydraulic Diaphragm Metering Pumps
Metering pumps with hydraulically actuated designs are usually preferred for the harshest chemical-handling conditions. They offer longevity with minimal maintenance because the diaphragm is hydraulically balanced and the key moving part is always submerged in a bath of hydraulic fluid. Hydraulic diaphragm metering pumps are able to pump against extremely high pressures and offer repeatable dosing accuracy of +/-1%.
Solenoid Diaphragm Metering Pumps
Solenoid actuated (or electronic) metering pumps offer great economy and efficiency. They are great for low-flow and/or low-pressure chemical dosing applications. They do have their limitations, though, and thus are not ideal for every chemical metering application. Repeatable dosing accuracy is usually within +/-3%. You can reduce capacity to increase pressure load capability.
This simplistic pump type is excellent for handling viscous and abrasive chemicals. They are able to run dry and the tube system pushes sensitive chemicals safely through the pump system. Peristaltic pumps are often used as an alternative to progressive cavity pumps in chemical metering applications because their rotors and stators will not be damaged in run-dry conditions.
Milton Roy Chemical Metering Pumps
Milton Roy is one of the leading manufacturers we turn to when a customer comes to us with a chemical metering need. MilRoy offers several different series of metering pumps designed for precise chemical dosing. Depending on your application, you will definitely want to consider one of their excellent chemical pumps in one of these product series:
- CENTRAC Series
- MaxRoy Series
- MilRoyal Series
- Proteus Series
- PrimeRoyal or PrimeRoy Series
When it comes to chemical metering, you need the right pump for the job. Contact DXP Pacific today to learn more about chemical metering pumps from Milton Roy and other leading pump manufacturers. Let our team help you select the best metering pump for your specific chemical processing application.