All About Chemical Dosing Pumps.
What Are Dosing Pumps?
A Chemical Dosing Pump or "metering pump" is designed to dose a precise volume of chemical reagent into a process. They are often used to pump chemicals or solutions, to a process vessel or pipework, usually pumping from a chemical drum that's either 25L, 205L or an IBC. We also offer a range of chemical dosing tanks from 50 to 1000 litre capacity.
Usage of a Dosing Pump
A dosing pump can have a wide variety of uses. They are typically for injecting either a chemical or a solution into a system to start a chemical reaction. From neutralising pH to creating a product, the application of dosing pumps are numerous from simply dosing swimming pool water to complex batch operations of chemical reagents into process vessels.
A Typical dosing system consists of:
- A Dosing Tank and Bund Tank consisting of the chemical you wish to input into the system.
- A Suction Lance Assembly in the tank often with low level output and a non return valve.
- A Dosing Pump which may have manual output adjustment or automatic output adjustment.
- Dosing tubing in a material non reactive to the chemical to safely carry the chemical reagent.
- An Injector fitting with suction NRV (non return valve) to prevent bulk feeding of the process' solution.
Foot Mounting, Surface Mounting & Control Functions.
Dosing pumps are availabe for mounting onto flat horizontal surfaces such as tank tops or shelves, known as foot mounting pumps. Or for mounting on flat vertical surfaces such as wall mounting or on back plates for when dosing into manifolds.
Dosing pumps are available with many different control functions. These include: Manual output adjustment via a potentiometer usually 0 -100% of the pumps rated output such as the AT2-BX dosing pump, (the BX signifies its manual output adjustment). Manual Output with low chemical cut-out via a potentiometer usually 0 -100% of the pumps rated output with a low level float switch connection to stop the pump running dry. Manual or automatic output control is selectable. Manual control with a potentiometer, or automatic control via an electrical signal which is selectable for PFM pulse frequency modulation, which are a series of VFC (Volt free contact) closures or pulses usually from a contacting head water meter; an AWE Limited pH Controller; a PLC or a 4-20ma control signal from a Process Controller.
Choosing the right Chemical Dosing Pump for you.
Water Treatment, Effluent Treatment and Process Control applications often include a requirement to add a chemical reagent to a process. This is why choosing the right dosing pump for you is so important. There are significant variables that could impact your decision, including the type of chemical reagent to be added. Also the flow rate, the pressure and the nature of the control process. This is why our online chemical compatibility checker should be used. With this you can check a range of chemicals against the parts of a dosing pump, or check the material of a dosing pump against the chemical so as to ensure that the pump doesn't degrade over time and for the safety of those working with dangerous chemicals.
Depending on the application you might need a specific type of pump for your process; either to allow automation or to integrate some of the process into the pump. Below we break down each dosing pump and why they might be useful for the application you require.
While each pump within our dosing pump range is able to operate in a constant dosing mode with a manually adjustable output, we also offer a specific dosing pump range designed to run in this way. This is where the pump is switched on or off either manually or from a controller, such as a timer, pH controllers, conductivity controllers, or practically any other controller.
Many control applications call for precision dosing of chemical reagent based on a pulsed input. Common applications include sodium hypochlorite dosing pumps, which dose proportional to the flow, based on the signal from a water meter when chlorine dosing or biocide dosing applications.
Proportional control dosing pumps are frequently used as acid dosing pumps or alkaline dosing pumps. Here a pH reading allows a pulsed signal from a pH controller or pH transmitter, to allow the pump to speed up or slow down to accurately maintain a set pH.
As an alternative to a pulsed input signal dosing pump, you can use a 4-20mA dosing pump. These dosing pumps dose proportionally to a 4-20mA input signal. In this instance, on a 4mA signal, the dosing pump stops metering chemical reagent into the process and at 20mA the dosing pump speeds up to deliver up to 100% of the pumps rated output.
4-20mA input dosing pumps are frequently used in process control applications, such as pH correction, solution strength control and many other metering pump applications.
Microprocessor controlled or Smart Dosing Pumps are designed to integrate some of the control process into the metering pump itself.
Used for manually adjustable dosing from 0 - 100% of the rated output; working with a pulsed input signal from a water meter or controller, offering the ability to multiply or divide the signal. They can also work with a 4-20mA input signal which can be configured with the dosing pump software.
PPM Dosing to Maintain a desired PPM of chemical based on the input from a water meter, making them ideal as a chlorine dosing pump.
They can also be used to batch dose a desired amount of chemical also called Batch Dosing. Where the user inputs the amount of chemical to be transferred, e.g. 50 Litres, and the dosing pump will then automatically meter this amount of chemical into a process.
Timer Dosing is when the pump will dose for a preset time, for example 20 minutes, and can then be automated based on an incoming signal.