Top 10 questions about liquid dosing

Before we start; in what kind of applications are dosing systems used?

“We see many applications in the field using liquid dosing systems. For example, in the:

• food industry to add fragrances and flavourings
• household chemical industry to add dyes to detergent
• perfume industry to add fragrances, and
• petrochemical industry to dose additives like catalysts and odorants

There are several options how you can dose additives; with a flow meter combined with a dosing pump or just a pump. Throughout the years, we gathered the most frequently asked questions.”

Dosing additives with a flow meter and/or dosing pump

1. What’s the difference between liquid dosing with just a flow meter, and using a flow meter combined with a dosing pump? 

“Our flow meters precisely measure and check the quantity of liquid being dosed. This allows for extremely accurate dosing, which has several benefits: 

• Savings in raw materials and additives; 
• Better process quality; and
• Traceable flow values.''

2. What is important to know if you’re dosing liquids at a low flow rate?

“It’s important that you purge your process well. A small air or gas bubble can distort the dosing process and measurement values for your process. We have a great deal of experience with these kinds of processes, and can give you advice on how to tackle this issue. We’ve also produced an ebook which you can download for free. The ebook explains in detail how to handle low liquid flows, with a focus on liquid flows under 100 g/h.''

Download E-book

4. Can I connect your flow meter to my dosing pump in an existing process?

''Yes, absolutely. By connecting the flow meter to a dosing pump, you can measure exactly what the pump is doing. Flow instruments can often be used to control the pump for greater precision. This is a significant added value offered by our flow instruments. Bronkhorst can help with advice and on-site system installation. Find out more about the possibilities we can offer you.''
 

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Liquid dosing system

5. In my process, can I switch between continuous dosing and batch dosing?

''Yes, you can realise different types of dosing using the integrated PID controller and the batch controller in our Coriolis and ultrasonic flow instruments. This allows for continuous dosing, where the flow controller maintains the flow rate in the process at a set value. If the setpoint is changed, the system immediately adjusts. You can also track the output signal from another flow meter, allowing you to adjust, mix or blend other additives (in ppm). This is called ratio control; a ratio of the main flow is mixed or blended into the main flow.

As well as continuous dosing, you can also do batch dosing. With batch dosing, the PID controller regulates the fill times. For extremely short fill times, less than a couple of seconds, open/close valves are used.''

6. Can you also fill jars?

''Yes! Filling jars is quick and easy using the batch controller function on our Coriolis and ultrasonic flow meters. You only have to enter the batch value on the flow meter once, then for each batch you can simply re-start the counter. If desired, the batch controller can automatically adjust to the changing conditions.''
 

7. What kinds of speeds can be achieved for my filling process?

''For dosing applications, speeds of up to 50 msec can be achieved using special on/off valves. You often see these in production lines where jars or soft drink bottles on a conveyor belt have to be filled quickly with flavourings or other additives.''

Read more about batch dosing in our blog: fast batch dosing in filling lines.

8. What kinds of quantities can I dose?

''For a process with continuous dosing, anywhere from a couple of mg/h (with the u-FLOW series) up to around 1000 kg/h (with the CORI-FLOW series). With batch dosing, the batch size depends on the dosing time and maximum flow rate, so it varies from 50 μg to 278 g in around one second, up to many times that amount if the dosing times are longer.''