Sensors
Below are some sensors that I came across while working on the library. There are many more out there and the best choice strongly depends on the application.
- Flow rate range: 1–60 l/min
- Precision: 3% (flow rate from 1L/min to 10L/min)
- K-Factor: 5.5
Source: Seed Studio.
Note that while the range figure suggests a turndown ratio of 60:1, the limits to the precision figure indicate an actual turndown ratio of 10:1.
The flow rate vs. frequency diagram shows two slightly different specimen of the same sensor type. While the difference may seem small, your sensor may vary.
- Flow rate range: 1–60 l/min
- Precision: none stated
- K-Factor: 4.8 (sometimes falsely stated as 56)
Source: Ultisolar
This sensor is similar to the FS300A. Suitable for irrigation and wherever precision isn't crucial.
The values in this diagram indicate a different K-Factor for this sensor model (i.e. different frequency per flow rate values). This is a direct result of the larger impeller compared to the FS300A.
It can also be adverse to assume linearity over the whole turndown ratio, let alone the complete range. Note how the diagram starts at 2 l/min and ends at 10 l/min, that's a linear range of only 5:1.
- Flow rate range: 0.05–1.2 l/min (depending on model)
- Precision: 2%
- Repeatability: 0.25%
- K-Factor: 20–40 (see datasheet)
Source: Digimesa
A rather well documented flow sensor for the vending machine industry. Suitable in applications with lower pressures and flow rates.
Higher precision than the above examples, calibration factors can be derived from the datasheet.