Flow Meters

In flow metering the Doppler effect occurs when ultra-sonic waves hit particles or bubbles in the fluid and change tone. 
 
It is important to note at the time of purchase that Doppler flow meters do NOT work with ‘ultra-pures’ such as  water, milk, alcohols, beers etc.
As a lack of bubbles or impurities results in no signal.


Time of Flight Flowmeters work because the ultrasonic signal passing through a pipe is slowed down when it opposes the flow.
 
Examples of applications include glycol refrigeration, milk, for comparison with installed flowmeters, shipboard (seawater), river water. Learn more 


 

Variable Area Flowmeters

 
Familiar to anyone who’s been in hospital and seen the oxygen or suction meters above every bed, the Variable Area Flowmeter or ‘Rotameter’, remains a simple and reliable method of measuring the flow of both liquids and gases.
 
Technically the term Rotameter is a trade name, but as ‘Hoover’ now often means ‘vacuum cleaner’, ‘Rotameter’ now often means variable area flowmeter.
 
Patented in 1908, the rotameter is a tube in which a float resides. The diameter increases as the tube gets higher.  Hence increasing flow produces a nearly linear display of flow.
 
Although data sheets rarely mention it, a rotameter must be installed for vertical upwards flow to allow the float to lift off the bottom stop and give a reading.
 
Homershams supply rotameters from Dwyer (USA) and Influx (U.K.) in both simple acrylic blocks and metal frames with separate tubes.

 

Flow Switches

Flow switches are used for pump protection and to confirm flow is happening. The simplest flow switch will usually have a reed switch mounted in the main body and a magnet on the end of the paddle. As the paddle moves back & forth with the flow, the switch is operated either on or off.
 
Homershams have many flow switches especially from Dwyer including paddle type and Thermal Dispersion (no moving parts).  There are too many to list, but here are a few examples of our most common ones.

Did you know..

The term ‘Potable’ refers to water that is designated for human consumption, but many people are unsure of the correct pronunciation - it’s “Poe-ta-bull” from the Latin word Potibillis meaning “to drink”