When transloading liquids, measurements need to be highly accurate for both the seller’s purposes as well as the buyer’s. This is why flow meters exist – to measure the flow rate of certain liquids or gases and correctly determine the amount of product being transferred.
There are several types of flow meters, but today we will talk about three: Coriolis, Positive Displacement, and Turbine meters.
Coriolis Flow Meters
Employing the Coriolis effect, the Coriolis meter has a tube that vibrates laterally in order to distort the liquid or gas so it can measure mass flow and density. Coriolis measurement is very accurate no matter the type of gas or liquid being measured. The Coriolis uses its “swinging” motion to create vibration in the tube where fluid is flowing.
Coriolis meters are versatile enough to measure fluid density, flow, and the temperature of the outside wall on the flow meter pipe. Some can measure fluid viscosity or two-phase flow. Direct mass measurement is what sets Coriolis meters apart from all other meters. Mass measurement is not sensitive to changes in pressure, temperature, density, or viscosity so this meter can measure liquids, slurries and gases. Coriolis meters are the most expensive of the three, but if your applications require extreme accuracy this is the ideal meter.
Positive Displacement Flow Meters
Positive displacement meters measure, mix, batch and dose many types of fluids including chemicals, water, hydrocarbons, and some other liquids.
Abrasive or dirty fluids can damage the sealing surfaces, bearings, and/or plug the flow meter. A filter will remove dirt and debris and keep the flow more consistently. Ensure gas bubbles are removed from liquid flow streams, too. Bubbles will throw off the true liquid flow compromising the meter’s effectiveness. A gas eliminator may be used to correct this problem.
Turbine Flow Meters
Turbine meters measure velocity of hydrocarbons, petroleum, chemicals, water, air, and industrial gases as they travel through pipes. A turbine wheel is set in the fluid stream so that the moving fluid pushes the turbine blades and sets the rotor in motion. Once a steady speed is reached, it is proportional to the fluid’s velocity. Since the flow direction is straight through the turbine meter, it can achieve higher flow rates and less pressure loss than displacement meters.
Strainers are often used in front of the meter to catch gravel and any other debris. Often, turbine flow meters integrate a flow computer to correct for temperature, pressure, and fluid properties.
Often preferred because of their low cost of installation, maintenance and ownership, turbine flow meters provide good accuracy and repeatable measurement even under the demanding conditions of oil and gas custody transfer applications. They also have a high tolerance to vibration and shock.
Conclusion
Basic features of the three meters are as follows:
- Coriolis meters measure mass flow and density with accuracy. They are high in price but worth the cost when you need superior accuracy.
- Positive Displacement meters measure volume. They are less expensive but beware of drops in pressure plus any debris or bubbles in the fluid.
- Turbine meters measure velocity. They are low cost, have a high tolerance for vibration and work at higher rpms.
If your business needs a flow meter for custody transfers of chemicals, water, oil and gas or other liquids, check with Carbis Fluid Handling. We will evaluate the properties of the fluids to be metered and determine the metering system that will work best for your application(s). Carbis Fluid Handling will save you time, money and headaches caused by purchasing the incorrect meter and/or using it improperly. Contact us today at 1.800.823.0163 in the US or at (+1) 843.656.1318 Internationally.
