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Flowmeters or flow sensors can be defined as devices that can help to measure the flow rate of a substance. In other words, such instruments show how much liquid or gas is flowing through pipelines or other enclosed systems and at what rate.
Interestingly, the necessity of measuring airflow and water distribution was eminent in the ancient world, as early as 5,000 BC, especially for navigating, water supply, and agriculture. Yet, it was in 1908 when the German engineer Karl Kueppers developed the first true variable area (VA) flowmeter with a rotating float, also called rotameter. Meanwhile, the first glass rotameters manufactured in the UK. Note that as of 2016, the Japanese company Yokogawa Electric Corporation holds the patent for the rotameter. Flowmeters, originally designed to measure liquids, evolved over the years (particularly in the 50s) and started being utilized in gas and steam flow measurements.
From positive displacement flowmeters and Coriolis units to Vortex meters and turbine models, now different types of flowmeters can be used in different specialized areas, such as manufacturing settings, households, health research, municipality systems, and mining. Also, flowmeters can be used for energy saving to measure different fluids, including oil. Note that some modern equipment can connect to computer software to monitor changes over time and detect errors.
How to Choose a Flowmeter
Choosing a flowmeter can be a challenging task, especially for non-specialists and do-it-yourself enthusiasts. Prospective buyers should consider various aspects, such as the fluid being measured, its viscosity, and the size of the piping system; users should also decide if they need a local display or a digital output of the collected data. To be more precise, the three main areas buyers should asses are:
- Total costs
Requirements: The first aspect to consider is the fluid being measured (e.g., water, gas, oil). The fluid’s characteristics should be taken into account, such as pressure, temperature, density, composition, conductivity, toxicity, light transmission, and viscosity (of both Newtonian and non-Newtonian fluids). Another important factor is the piping system and its interaction with the fluid of interest. Based on their requirements, users can choose from paddle wheel, piston, thermal, oscillatory, electromagnetic, Karman vortex, ultrasonic, positive displacement, and other flowmeters. Note that variable area flowmeters are among the most common type of meters used today. Last but not least, prospective buyers should decide if the information (continuous or totalized) will be used locally or remotely, including digitally.
Specifications: One of the leading parameters to consider is a unit’s Reynold’s number. We should mention that this number should correspond to different fluids and their viscosity levels. Users should also choose appropriate measurement ranges; note that the turndown indication on any flowmeter should show the lowest and the highest numbers it can support. Additionally, choosing a flowmeter should be based on its accuracy. Interestingly, when it comes to meters with and without moving parts, flowmeters without moving parts are preferred as additional fragments may lead to wearing and inaccurate readings.
Total costs: Deciding on a budget is vital. While it’s true that inexpensive units might be inferior in design and performance, it is noteworthy to mention that measuring water and airflow at home does not always require specialized equipment; nevertheless, some cheap units may come with high installation costs and risks. Note that in case users need to know the rate at which a fluid is moving – not to control it – they can invest in simple flow indicators instead.
Variable Area Flowmeters in Detail
Variable area flowmeters, as stated earlier, are some of the most common meters for sale. They are ideal for low-cost solutions and can be used to determine flow/no-flow indications. Purgemeters, on the other hand, are ideal for low-flow settings. Note that VA units vary according to their float shape and material; there are plastic, glass, and metal models that can be used for different fluids and applications.
Here we should mention that some of the leading manufacturers are KROHNE (ideal for chemical processes and wastewater settings), Blue-White Industries (offering acrylic and polysulfone VA meters, as well as tube and block units), Brooks Instruments (producing units ideal for low and high-flow measurements, as well as MT Series models for aggressive fluids), and Yokogawa (offering different transmitter outputs).
Best Flowmeters for Sale
Interestingly, while VA flowmeters are affordable and convenient, turbine and positive displacement meters have expanded their market size significantly. Based on different parameters and user reviews, here are some of the best flowmeters available on the market:
It is a durable flowmeter suitable for both home use and commercial applications. Note that the unit is designed to measure horizontal water flow, with an easy-to-read dual scale (SCH 40/SCH 80). With its convenient Pilot Tube design, this meter is easy to install on an existing piping system (suitable for PVC and copper pipes); the set comes with a gasket seal and mounting clamps. Last but not least, it is worth noting that this one-piece acrylic meter body is suited for closed pipe installations, as well as outdoor installations.
It is a great meter designed to measure gas flow. Moreover, the unit can be used as a regulator and a flowmeter at the same time (4000 psi/kg/cm2). Note that this meter is calibrated for argon and CO2and its hose nipple fits both ¼-inch and 3/16-inch systems, which also makes it ideal for regulating shielding gas during metal inert gas (MIG) and tungsten inert gas (TIG) welding. With its solid brass body, easy-to-read 1.5-inch gauge, and rubber gauge protector, Ameriflame RF2480-320 is a highly favored flowmeter.
It is an advanced digital meter designed for water, di