How to Read a Flow Meter

Properly reading your flow meter depends on which flow meter technology is associated with your flow meter.

Most medical flow meters employ a variable area principle of measurement with a float indicator and a scale on a clear tube. The flow rate determines how high the float moves up in the tube and the flow rate is read from the float.

If you are looking for an answer to the question of “how do I read a flow meter”, chances are your flow meter is one that utilizes float indication in a clear tube. Where you reference the flow on a float type indicating flow meter, like the popular variable area flow meter (or rotameter), depends on the specifications stated by the manufacturer of your exact flow meter.

Always refer to your manufacturers datasheet and do not use generalizations that you may find on the internet, to ensure the accuracy of your flow readings. Most KOBOLD float type flow meters are read at the top of the float. Simply locate the top of the float and reference it to the scale printed on the outside of the flow meter. Make note of what units of measurement your scale in printed in to avoid misinterpretation of the flow rate.

When reading a float type flow meter, it is important to be aware of something that is referred to as parallax error. This refers to the phenomena that viewing objects at an oblique angle can cause a distortion between the actual place of something and the place we perceive it to be. To avoid this visual distortion and ensure the most accurate reading of the flow rate, read the flow meter from a close distance, straight in front of the meter, with your eye as level to the float as possible.

KOBOLD offers one of the industry's broadest lines of variable area flow meters and would be happy to help you learn how to read your KOBOLD meter or cross reference a KOBOLD model to replace one that may no longer be readable.

Reading a flow meter with a mechanical register is straight forward. For those of us old enough to remember, an example of a mechanical register is the old type of gas pump where the numbers flipped over on a pivot point, sort of like a slot machine functions. These sorts of displays are still used in applications today, even if they aren’t at the gas pumps in the US anymore. Reading mechanical displays is as easy as reading the number on the number wheels in order and the unit of measurement stated on the display.

These are also very easy flow meters to read. Simply locate the arrow, flap, or the digital terminus for the indicator and reference it against the scale printed on the flowmeter, paying mind to the scale’s units of measurement.

Most flow meters with digital displays will provide a read out on the display screen of your flow rate. Depending on the other functions your flow meter offers, you may need to use the integral electronics or menu to set the display to show the rate of flow as opposed to a batching process total, for example.

Digital flow meters will typically provide the flow rate. Some models can also show other elements like a resettable part-total for totalizing purposes and a non-settable grand-total that shows the total flow since the flow meter has been in use.

If you have a digital KOBOLD flow meter and are unsure about how to program the display to show the data you need, please contact one of our expert engineers who will walk you through the process or consult your product manual. If you have a digital flow meter with a display that isn’t working, our engineers would be happy to cross reference an ideal KOBOLD replacement for your needs.

Some flow meter technologies display the flow rate locally, where the element that does the measuring and the element that displays the flow rate are both together. One example would be variable area flow meters, also known as rotameters, that are mechanical in nature and the scale is physically printed on the device.

Some flow meter technologies and models can offer the option of a remote display where the measurement portion of the device is inserted or inline to the process piping, but the digital flow rate display is in a housing that is connected via a cable and placed away from the process.

For example, our MIM Magnetic Flow Meter is available with either an integral display that is housed within the flow body with the measuring device, or with a digital display separated from the magnetic measurement element with a connection cable.

There are three ways that flow meter displays are powered.

• Mechanical flow meters, like variable area flow meters, do not require power as flow itself technically provides the force that enables measurement
• Some are battery powered and are convenient where there is no readily available power source
• Some are powered externally through connection to an electrical source