How to install a metering pump correctly
The correct installation of a metering pump is essential to ensure optimal operation and to avoid potential problems or accidents. Below are some steps and tips for the proper installation of a metering pump.
Step 1:
Choosing the right type and model of metering pump
There are different types and models of dosing pumps, which are classified according to the operating principle, flow rate, pressure, type of liquid to be dosed, material of construction and control system. It is important to choose the type and model of dosing pump that best suits the needs and characteristics of the application. See our article How to choose a metering pump.
Some factors to consider when choosing a metering pump are:
Step 2:
Preparing the site and materials for installation
Before installing the metering pump, it is necessary to prepare the site and the materials required for the installation.
Some recommendations are:
Step 3:
Installation of the dosing pump
Once the site and installation materials have been prepared, the metering pump is connected to the system.
Metering pumps are generally self-priming, and there are a number of different types of pumps. two types of installation: in suction or on load. In general, it is advisable to install them under load (see illustration 1)The pump is positioned below the maximum height of the product to be dosed. In this way, greater dosing accuracy is achieved and vacuum operation is avoided. However, suction dosing is very common. (see illustration 2)For example, when the pump is installed directly above the canister or storage tank of the product to be dosed.

Illustration 1. Example of an installation under load

Illustration 2. Example of suction installation
Some tips are:
Suction pipe diameter (Illustration 3): It is of vital importance to choose the right suction line diameter in order to obtain a proper functioning of the dosing pump:
It is therefore recommended that the diameter of the suction pipe is the same as that of the suction valve of the dosing pump.
Suction pipe length: The suction line should be as short as possible. For "suction" installation, dosing pumps generally allow a maximum height of 1 m above the liquid level in the accumulation tank. This height could be extended up to 1.5 m for certain types of pumps, such as electromechanical diaphragm pumps with mechanical return (see Seko Kosmo dosing pump).

Illustration 3. Examples of correct installations
Suction filter (Illustration 3): In the event that the liquid to be dosed may contain particles in suspension, it is important to prevent these from reaching the pump, as they would end up accumulating in the suction and delivery valves (between the ball and the seat). This could lead to clogging of these valves, accelerated wear of their components and defective closing of the valves and, therefore, loss of efficiency of the metering pump. In these cases it is highly recommended to install a filter (foot or Y-strainer) in the suction line of the pump, always upstream of the suction valve.
As explained above, in this case it is also essential to choose a suitable filter size. Its diameter must be the same as that of the suction pipe. On the other hand, the filter mesh must be suitable for the flow rate of the dosing machine and the viscosity of the product to be dosed.
Dosing of viscous liquids: Some precautions must be taken when dosing viscous products:
In the Illustration 4 some examples of correct installation for viscous liquids can be found.

Illustration 4. Example of correct installations for viscous products
Back pressure valve (Illustrations 1, 2 and 5)It often happens that the height of the product to be dosed in its respective accumulation tank is higher than that of the dosing point, which could cause the entire product to be displaced through the dosing pump by communicating vessels or siphons, even if the pump is not active, with potentially catastrophic consequences in the case of corrosive or toxic products. To avoid this, it is necessary to install a back pressure valve. As a minimum pressure is required to open the back pressure valve, the outflow of liquid through the siphon is prevented.
On the other hand, a back pressure valve allows for greater precision in the dosing of the product since, by dosing at a constant pressure, a constant flow rate is obtained in the pump (the flow rate varies with the working pressure: the higher the pressure, the lower the flow rate).

Illustration 5. Installation of back pressure valve when dosing below product level
Pulsation damping (Illustrations 1 and 2): metering pumps cause vibrations in the delivery line due to their pulsed operation, which shortens the service life of the piping due to material fatigue and can lead to pipe rupture. Likewise, pressure peaks can occur in the delivery line, which can shorten the life of the pump. Therefore, it is advisable to install a pulsation dampener in the delivery line. In this way, a much more linear flow would be achieved, greatly reducing both pulsations and pressure peaks.
Safety valve (Illustrations 1 and 2): In the event of a blockage in the delivery line of the dosing pump (a frequent case would be, for example, sodium hypochlorite, which has a tendency to crystallise and clog the injection fitting) it could happen that, as pressure builds up in the delivery pipe, it could break at its weakest point (or even break some element of the pump), causing splashes of product that could affect personnel or surrounding equipment. To avoid this, it is recommended that a safety valve be installed, which would open if the pressure in the delivery circuit rises above a certain value. If there is also a back pressure valve, the safety relief valve should be set at a higher pressure than the back pressure valve.
Thus, the steps to follow would be:
Step 4:
Commissioning and adjustment of the metering pump
After connecting the metering pump to the system, it is started and adjusted. Some steps and tips are as follows:
Step 5:
Regular maintenance of the metering pump
To ensure the proper functioning and durability of the metering pump, regular maintenance is necessary. See our article How to maintain a metering pump.