As engineers, precise liquid flow measurement and control products are key to succeeding in your field of work. As your needs for these products arise, there are questions you may ask yourself regarding the type of product you need, its functionality and its ability to provide precise measurements.

Here at McMillan Flow Products, one of the most frequently asked questions we hear from prospective customers is “Will your sensor work with this type of fluid?” and here are three important factors to consider:

Viscosity and Transparency

The first and probably most important factor to take into account is the viscosity of the liquid being considered.  While flow sensors can measure various liquids such as semiconductor processing fluids, light oils, fuels, inks and other transparent or translucent liquids, viscosity plays an important role as a sensor will not work with liquids that are too dense (think “thick and syrupy”).

Because liquid flow sensors operate using an infrared light emitter that use the absorption or reflection of light to capture precise measurements of the fluid, the transparency of the liquid passing through is also important. For example, if the liquid absorbs all of the light from the emitter, then the flow sensor will not work.

Flow Sensor Bodies and Hazardous Chemicals

Another important factor to consider is whether or not the liquid you want to measure contains any types of hazardous or chemically aggressive materials that can damage the body of the flow sensor or the materials within the sensor itself. Hazardous chemicals can pose a problem to the flow sensor as the chemicals can damage sensitive parts of the device such as the fittings or O-rings.

Fortunately, there are alternative materials available that offer greater resistance to customer’s liquid types. Some other options available are brass, stainless steel or PTFE fittings that may be used in the sensor’s body – depending on the liquid.

Flow Range Needed

The final factor to take into account are the flow ranges for each sensor. Flow range sizing is important because a single flow meter can only accurately measure typically 10:1, so a unit rated for 10 L/minute will only measure as low as 1 L/minute accurately. An approximate gauge of flow rate can be determined by line size; our products typically connect to tubing with diameters ½” and less.

Our flow ranges start at 0.05 mL/minute and go up to 50 L/minute. Generally, the range of each sensor is 10% to 100% of the full flow rating of the sensor with some variations of the low flow rating depending on the flow rate to be measured. The model of the sensor is matched to the range of flow rates that are required to be measured.

Some other options and considerations may be:

  • Type of output signal needed for your data
  • Power supply requirements
  • NIST traceable calibration if desired

What kind of liquids do you need help measuring? How may McMillan’s Liquid Flow Measurement Products help you? Please contact us with any questions you might have about our liquid flow sensors and other products.