How to achieve precise dosing

How to choose the appropriate pump and build a flexible and efficient pump system?

Usually, when selecting pumps and systems, factories will consider the actual operating conditions in the future. For example, municipal water plants may consider that as the population grows, the pumping volume will increase; Production plants affected by seasons or cycles, such as refineries, require flexible reduction in pumping volume when demand decreases.

Therefore, the metering pump should be able to flexibly adjust the flow rate according to different process conditions, and the adjustment ratio has become an important indicator for measuring the output performance of the metering pump.

What is regulation ratio?

Adjustment ratio=maximum output flow rate of metering pump: minimum output flow rate

If the maximum flow rate of the metering pump is 1000LPH and the regulation ratio is 1000:1, the minimum flow rate can be adjusted to 1LPH.

Why is regulation so important?

Let's take a look at how the adjustment ratio can help factories cope with precise dosing under process changes from two important industry applications.

Addition of water treatment chemicals

Coagulation/flocculation/pH control/dechlorination/disinfection and various odor control

● Water treatment plant: Its water intake and quality change every day, so water treatment requires the mixing and precise dosing of different chemical agents. Excessive injection of medication can result in waste and high costs, while insufficient dosage may cause harm to the human body.

● Water treatment plants along the river: more flexible treatment is needed to cope with the increase of mud and sediment in the water after rainstorm.

● Large lakes: The turbidity of their water quality changes relatively little, so the dosage of chemical agents used by treatment plants along the lake shore may not change significantly. However, some chemical agents may have lower concentrations at high temperatures, so the adjustment ratio may vary with the seasons.

Chemical dosing for upstream production of oil and gas

The flow assurance agents used to maintain the flow of oil and gas in oil and gas wells are very expensive and usually stored at high concentrations on site. Therefore, for some producers, when oil prices are below the breakeven point, flow assurance agents provide an opportunity to cut costs.

Therefore, ensuring the effective distribution of flow assurance agents is crucial, and the adjustment ratio of the metering pump precisely helps to improve its accuracy

Is it really better to have a higher adjustment ratio?

In recent years, there have been increasing doubts about the regulation ratio and claimed performance of different pumping technologies. In a world where 'more is better', some manufacturers inform users that the pump has a high regulation ratio (up to 1000000:1) based on the maximum flow rate of the pump, rather than based on the actual set value.

So, what does this really mean?

For metering pumps, discussing the adjustment ratio outside of the set value is meaningless - because the operating range of any pump can be from 0 to maximum flow, so the adjustment ratio of any pump can be described as infinite

What does high-profile competition mean?

Assuming the maximum flow rate of a metering pump is 100LPH:

● When the adjustment ratio is 10:1, the adjustment range of the metering pump is 90% of the maximum flow rate (between 100LPH and 10LPH).

● When the adjustment ratio is 100:1, the adjustment range of the metering pump is 99% of the maximum flow rate (between 100LPH and 1LPH). The adjustment ratio has increased from 10:1 to 100:1, which sounds like a tenfold increase, but its adjustment range has only increased by 9%.

● When the adjustment ratio is 1000:1, the increase in adjustment range can be almost negligible, only 0.9% (between 100LPH and 0.1GPH). Although 1000:1 is 10 times higher than 100:1, in this example, only 0.9LPH, or 0.9% of the maximum flow rate, was actually increased.

What is the required adjustment ratio for the manufacturing process?

When designing the process flow, the adjustment ratio needs to be set, and a high adjustment ratio can compensate for the deviation between the set and actual drug dosage values. But in reality, a 10:1 adjustment ratio can already meet the needs of most municipal water treatment and industrial production processes.

Normally, if the application requires a regulation ratio greater than 100:1, the volume of the metering pump may increase - meaning it will operate at the optimal efficiency point (BEP). This not only reduces efficiency, but also lowers the mean time between repairs (MTBM) interval.