When selecting a flowmeter, you need to take into consideration what kind of liquid or resource you’ll need it for. A water flowmeter would measure the flow rate of water more accurately than any other. Steam flowmeters for steam, gas flowmeters for gas. Some flowmeters are marketed to work for all kinds of liquids. And what if you’re working with fluids that are not water, gas, or oil? For example, if you need to watch the flow rates of sewage water, paint ingredients, or chemicals used for manufacturing medicine. Those liquids are entirely different from water, so a person looking for flowmeters for these types of fluids needs to consider several key factors:
Liquids differ in density, but when it comes to reading their flow rates, liquid density is usually irrelevant. However, the same cannot be said when measuring the density of the gas. When it comes to gas, the density is related to how intense the pressure is or how the gas’ temperature is. The composition of a gas may also affect the density because the composition affects the gas’ compressibility factor. Unless compensated for, flow meters might give the wrong flow measurements due to inconsistent temperature and pressure.
The viscosity of a liquid affects how some flowmeters read the flow rate. Knowing which flowmeter works well with the viscosity of the liquid you are going to handle will help you get the right instrument that will give you accurate measurements. Some flowmeters, like variable area flowmeters, can be adjusted and calibrated to work with different liquid viscosities.
Temperature affects flowmeters in different ways. For gas, the density is equal to the quotient of the product of the gas’ mass and pressure, and the product of the gas’ compressibility factor, the universal gas constant, and temperature. For liquids, the temperature can affect the flowmeter itself and cause damage to it if the flowmeter isn’t made to resist high heat.
Another factor that affects density is pressure. Like temperature, the pressure is directly proportional with density and can change the measurements of flow rates as well. Flowmeters must be able to handle high pressures.
Finally, the composition of the liquids can affect the flowmeters itself. Some highly corrosive or very hot fluids could damage a flowmeter if it were not made to handle such liquids. The composition also affects the viscosity of liquid and gas.
With these points in mind, you’ll be able to ask for and find the right flowmeter that you need. Alternatively, you may also opt to buy a variable area flowmeter and have the meter calibrated to suit your purpose. Most flowmeters can be customised with additional features and different materials of construction, such as a power supply, an alarm and a transmitter if the flowmeter is going to be installed in restricted areas, or a valve to shut down the flow. You can also choose from a wide variety of displays where you can choose which one is easier to read. With such a wide array of flowmeters available there’s always one that will fit your needs.