How to select Mini small flow rate liquid flow meters?

Mini Small flow meters or low flow meters are widely used in many key areas, typically including micro injection in laboratory, medical infusion, precision filling, etc. Such application usually has small flow rate, e.g. 0.l to 100 liter per hour. It is better to select proper solution than expensive solution from big brand. In the text, we mainly introduce important information about selection of small rate liquid flow meters.

Common Misconceptions in Selection of Small Flow Meters

The characteristics of small flow liquids are complex, and wrong selection can easily lead to bad result. The following are several typical bad cases with wrong/ inappropriate selection:

(1). Regardless of liquid viscosity, use a turbine flow meter. Turbine flow meter is a kind of traditional flow meters and it is often seen in the market. Thus, many projects wrongly use this kind of flow meter. For example, in a syrup factory, a liquid has viscosity of 150cSt, turbine flow meter is used to measure the liquid. As a result, turbine is stuck, the flow rate is 0. It caused a result: filling volume is series shortage.

(2). Ignore corrosiveness and choose ordinary materials. For example, 304 stainless steel flow meter is used to measure acid plating solution. After about 2 months, the flow meter is corroded to be perforated. As a result, the corrosive liquid is leaked and causes much loss.

(3). Ignore installation space and choose flow meter with bigger size body. For example: The internal space of the infusion pump in a medical equipment is only 10cm × 8cm, but purchased a flow meter with size over 20cm. As a result, the flow meter can’t be fit in at all, and have to be returned. It wastes time and money.

3 Important Steps to Judge Small Low Rate Flow Meters

The examples above let us know it is very necessary to do right selection. The following are 3 important steps can help to select proper solution rightly.

Step1: Ask about the fluid medium – anti-corrosion, anti-adhesion

(1) Water based/low viscosity liquids (such as purified water, alcohol): Recommend mini clamp on ultrasonic flow meter and small magnetic flow meters. Mini clamp on flow meter has small size body and low flow rate measurement, and doesn’t require to cut pipe, no pollution to liquid.
Small inline mag-flow has higher accuracy and can provide different shape/structures. But magnetic flow meter has a certain standard for electric conductivity, and clamp on ultrasonic flow meter has no such requirement.

Step 2: Check Flow Rate Range and Pipe Size

Flow rate and pipe size has certain relationship. Flow rate should meet the requirement of project. Otherwise, actual flow rate is out of the flow range, it will make the flow measurement to be reliable, even may cause loss.
Usually should firstly check pipe size/tube size, then check flow range (or flow velocity), then select proper flow meter.
In regard that if pipe size is very small, flow rate may be a first consideration factor. For example, when pipe size is DN6mm, the flow rate is bigger, and can change pipe to DN4mm, by this, flow rate may fall into proper range.

Step 3: Check Installing
(1).Narrow space (such as inside equipment). Under such condition, it is necessary to consider mini size flow meter, e,g, mini size clamp on flow meter or mini size magnetic flow meters. Traditional structure flow meters can’t be suitable even though it has small low flow rate.

(2). No or less straight pipe section (such as pipeline bends). Mini size magnetic flow meter has less or no requirement for straight pipe section. Thus, if possible, firstly consider mini size mag-flow.
If the installing is at pipeline bend, it is better to use min rotary flow meter. For example, in a lab, a rotary flow meter is installed at the turning point of a reactor feeding tube, which has no straight pipe section, and the accuracy is still ≤ ±1.2%.

In regard that small flow application may be a complicated issue and you can’t decide which solution is proper. If so, please contact us. We have experience for thousands of cases and can recommend proper solution with proper price. If want to contact us, please just give us the following information:
(1) Fluid medium content: e.g. 5% glucose solution; lubricating oil with viscosity of 200cSt,etc.
(2) Flow rate range and pipe size
(3) Pipe material. e.g stainless steel, copper, PVC, etc.
(4) Installing Condition:
(5) Fluid temperature range
(6) What signal output is required

The core of selecting small flow rates is “matching working conditions”, rather than blindly choosing expensive or BIG Brand. As a professional manufacturer, we can help to select proper solution with proper budget, and turning small flow rate measurements from “troublesome” to “easy”.