Going with the Flow: When Are Swagelok Area Flowmeters Needed?

Measuring flow in a fluid system is just as important as measuring pressure

As much as we blog about pressure, it's just as important to think about the rate of flow in a fluid system. After all, the whole idea behind fluid systems is to get the liquid or gas from Point A to Point B. That's flow. And what's the crucial graph that we look at when checking the performance of a pressure regulator? Right: a flow curve. Flow and pressure go hand in hand.

For simple applications such as an air or water line, it may be enough to know that the fluid is getting through. For everything else -- and even for some of the simple applications -- you want a precise measurement. The most basic measurement device is the variable area flowmeter. It measures the flow rate of liquids and gases by means of a tapered tube and float. The float is pushed up by increasing fluid flow and pulled down by gravity as fluid flow decreases. No external power is required, though Swagelok does offer some electronic options.

Swagelok has a full line of flowmeters for various applications. Take a look at your choices online by downloading the catalogue. The product line includes custom-calibrated flowmeters for fluids with properties substantially different from those of air or water, as well as systems operating at higher pressures or temperatures.

What to know

As with gauges, regulators or other pieces of equipment, it's important to match the model to the job. In liquids, for example, higher temperature can reduce viscosity and density, resulting in lower readings. In gases, higher fluid temperature can increase volume and result in higher readings. You can buy the most expensive flowmeter in the world, but if you don't have the right specifics on the application, the accuracy won't be there.  So when you contact your sales rep at Edmonton Valve and Fitting, have a few pieces of information handy:

* Type of fluid to be measured

* Fluid temperature

* Fluid viscosity

* Fluid specific gravity

* System pressure

* Measurement range.

That last item, measurement range, is especially important. A flow meter works most accurately in the middle third of its measurement range. If you have too broad of a range, it will be hard to accurately determine the flow.

Once you have your flowmeters in place, it's a good idea to follow up with a calibration program, checking every so often that you are still getting accurate readings. Other than that, very little maintenance is required.