Coriolis Measurement
- Since the 1980’s Coriolis meters have slowly replaced the traditional meters such as turbines or PD meters to become the most popular liquid meter on the market.
- Over the last 10yrs Coriolis meters have gained popularity in gas measurement, even replacing traditional ultrasonic, and orifice measurement.
- Having to maintain, operate, troubleshoot thousands of measurement points throughout my career I have found that as great as Coriolis meters are, many short comings still exist when it comes to fluids that have:
- Combined low flow and light densities
- Dirty products that leave residues
- Supercritical fluids
How Does Coriolis Meter Work
- Without too much math the basic idea is you have a bent tube that is vibrating with no fluid moving through it. As fluid begins to flow through this bent tube the tube will twist from the flow’s inertial forces. These inertial forces are created by the fluids mass and change in velocity between two points, yielding the famous F=ma equation.
- The rate of the twist and speed of the twist corresponds to the mass flow and density of the product.
Understanding How Density Effects Force
- Density is physical characterization of how much an object weights per unit of volume. It is typically expressed in units such as g/ml or lbm/cuft
- Mass= Density x Volume
- Force= Mass x Acceleration (change in velocity)
- In a Coriolis meter, I have a known tube diameter and length of the tube the nominal volume of the fluid contained is known
- Mass in the tube= Density*(volume of tube)
- Inertial force (F= ma) tells us that the force changes directly with the weight (mass) of the fluid which is related to density of the fluid
Understanding How Flowrate Effects Force
- In a Coriolis meter, when a fluid is flowing through the tube it twists. The rate of twist is related to the change in the fluids velocity otherwise known as acceleration.
- Inertial force (F= ma) tells us that the force changes directly with acceleration
Thermo Properties of Hydrogen
Hydrogen Density at 100F
- Majority of most gaseous state pipelines in the Untied States operate between a pressure of 400-1400psig.
- The density of hydrogen is linear over this range.
What Question to Ask?
- When determining the accuracy of a meter installation.
- What is the minimum flowrate I need with the products density range I expect to be able to create enough inertial force to twist the tubes such that the sensors picking up the tube movement can register meaningful motion.
