| Flowmeters are used in many ways but their basic | | | | instance, the production of many processed foods is |
| aim is to measure the flow of a particular substance | | | | largely automated. There may be a human operator |
| passing through a tube, pipe or chamber. Why would | | | | that needs tools like a flowmeter to check that the |
| you want to do this? Well, you could say one of the | | | | right amounts of various ingredients are going into |
| reasons is to assess the well being of the machine | | | | the machine. If the wrong quantities are used the |
| that is being measured. Another reason may be to | | | | food does not taste right or may have to be recalled. |
| assess that the machine is operating correctly. This | | | | In these industries there are a variety of flowmeters. |
| article will illustrate some of the flowmeter types and | | | | The most common are ultrasonic flowmeters and |
| discuss how they are used. | | | | thermal dispersion flowmeters. They can measure the |
| Peak flowmeters are used to measure the rate of air | | | | flow rate of gases and liquids so have plenty of |
| flow out of the lungs. Peak flowmeters are used to | | | | applications. |
| assess or gauge the condition of a person's lungs. | | | | The principal behind the ultrasonic flowmeter is that |
| This is sometimes used as part of a fitness test as | | | | the change in the frequency of an ultrasonic wave |
| the rate at which air can be exhales from the lungs | | | | can be used to correlate the flow rate of the |
| indicates the capacity of the lungs and determines | | | | particular substance that has caused this change. This |
| the level of physical activity a person can undertake. | | | | is the same principal behind the Doppler shift |
| However a peak flowmeter is more commonly used | | | | flowmeter, that is commonly used to measure liquids |
| to determine whether someone is asthmatic or is | | | | that contain particulate matter, like effluent, waste |
| used to manage the condition once it has been | | | | water or reclaimed water. |
| diagnosed. | | | | Thermal dispersion has a similar idea except that it |
| A peak flow meter is a common type of flow meter, | | | | uses the change in heat from a particular heat source |
| in that it uses the displacement method to determine | | | | located within the pipe or tube. The change in heat |
| the flow rate of air. The displacement method is | | | | will be directly related to the flow rate of the gas or |
| simply a float within a confined space like a pipe or | | | | liquid that is passing this heat source. |
| tube. When air passes through the tube it moves the | | | | Other types of flowmeter include the turbine, |
| float. The distance that the float moves indicates or | | | | magnetic and wheel flowmeters. Again, these devices |
| is a correlation of the flow rate. | | | | have applications in many larger scale industrial |
| In many industries, like HVAC, food processing, water | | | | complexes to ensure that a particular machine is |
| management, industrial and chemical manufacturing | | | | working correctly or is getting the right quantity of a |
| there are needs to measure the flow of various | | | | particular substance. |
| gases and liquids through large or small machinery. For | | | | |