Dosing chemicals - the importance of choosing the right dosing pump

When adding chemicals to your process, it is important that you dose them correctly. A dosing pump can help you dose the right amount of liquid, at the right time. Lyma clarifies the most common questions and tells you more about how you can improve both sustainability and profitability by making the right material choices.

Why chemicals?

It is important to get the right amount of chemicals continuously in the processes. Chemicals are used, among other things, to precipitate unwanted or environmentally hazardous substances or to make a liquid more manageable, e.g. defoaming. By adding chemicals to a flow, you can improve the outcome and create a process that is more optimal for both the environment and the budget.

How are chemicals added?

To ensure that the right amount of chemical is added to the process, a dosing pump is used. A dosing pump transports an accurately measured amount of liquid per unit of time into a process. The pump is often used for continuous dosing or for batch dosing of chemicals in processes where liquid in small quantities is to be dosed to a larger liquid flow. Dosing can be done, for example, by connecting the pump to a pH meter or water meter. Dosing pumps are used everywhere in industry, pharmaceutical manufacturing, water treatment plants, chemical plants, power plants or paper and steel industries.

Dosing pump

At Lyma we offer a wide range of dosing pumps for a variety of industrial applications. Depending on the type of liquid, flow and pressure that the pump is to treat, different requirements are placed on its design. Based on design, dosing pumps are divided into a few categories:

• Diaphragm metering pumps - the diaphragm pushes the liquid out of the pump head through the pressure side check valve, while the suction side d:o closes. The valves are usually check valves mounted inline, known as ball check valves. The liquid is fed into the main flow. The volume flow depends on the back pressure and is varied by variable stroke length and variable number of strokes. The dosing quantity changes proportionally to the stroke length and can be set reproducibly down to minimum capacity. The dosage is adjusted manually or with a 0/4-20 mA signal.
• Piston metering pumps - the piston pushes the liquid out of the pump head through the pressure side check valve, while the suction side d:o closes. The valves are usually check valves mounted inline, known as ball check valves. The liquid is fed into the main flow. The pumps can work against back pressure up to 400 bar. The dosing quantity changes proportionally to the stroke length and can be set reproducibly down to minimum capacity. The dosage is adjusted manually or with a 0/4-20 mA signal.
• Gear pumps - the pump has two gears, one driven by the other. The pumping medium is transported in the gap between the gears and the inside of the pump casing during rotation. The pump provides a pulsation-free flow and can work against relatively high pressures. The dosing quantity is regulated via a frequency converter connected to the electric motor.

Accessories

When dosing, a so-called lever effect can occur if the dosing medium is placed higher than the dosing point. It is then difficult to dose accurately, as gravity takes over. By installing a pressure control valve, the leverage is broken and the pump has a counter pressure to work against and can still provide accurate dosing.

The opposite problem arises if the pipes are blocked or you accidentally hit a closed valve. This can damage the pipes or the pump by building up too much pressure. Installing an overflow valve avoids unwanted pressure increases.

Learn more about our different dosing pumps and their applications

The importance of correct dosage

When it comes to dosing chemicals, great precision is required. To achieve the most optimal and safe process possible, it is important to dose correctly. All liquids behave differently when mixed, and initially a trial period is often needed to find both the right dosage amount and the right time interval. Brand new processes, such as carbon dioxide capture (CCS or CCU) with amines, create new dosing challenges.

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For the environment

Dosing the right chemicals and the right amount is vital, especially from a safety and environmental point of view. Chemicals can be explosive or corrosive. Leak proof pumps are therefore essential to ensure a safe process. Risk assessment is important and no matter how familiar you are with the media, you should always do a thorough background check to ensure that the material you are using is capable of handling the media in question.

Using a resistance table, you can easily and clearly see which material is recommended for your application. You can read more about resistance tables here.

For profitability

Adding the right amount of chemicals is not only important for the safety of the process but also for profitability. Buying chemicals is expensive and overdosing often causes extra wear and tear and labour. Using more chemicals than needed is therefore neither sustainable nor profitable.

Corrosive chemicals can make a big impact on materials and applications. By carefully selecting materials that can withstand your chemicals for a long time, you extend the life of your process and also reduce the risk of unexpected failures or stoppages.

Lyma helps you

We at Lyma have extensive experience with dosing pumps and can help you choose the right pump for your application. By carefully mapping and examining the medium that the pump will handle, we can suggest a suitable dosing pump that gives you an efficient process with low energy consumption, long life and above all high safety.

Learn more about our wide range of solutions

Learn more about how we work together to create safer flows.