Mechanical Flow Meter: Types, Advantages, and Disadvantages
A mechanical flow meter is a flow meter that uses an arrangement of moving parts to measure the flow. It does this by allowing the movement of specific known volumes of fluids in a chamber or gear. It also does this using a spinning turbine or rotor in turbine flowmeter arrangement.
Types of a mechanical flow meter
There are so many types of mechanical flow meters available in the market. Here are some of them:
Positive displacement flow meters
A mechanical flow meter gives good repeatability and high accuracy of 0.05% and +-0.1%, respectively. The pulsating flow does not affect the accuracy unless a gas or air enters the fluid.
You won’t need any power supply while using a positive displacement flow meter. Also, you won’t need a straight downstream or upstream pipe when installing it.
Gear and lobe meters
The oval gear positive displacement meter employs a pair of fine-toothed gears. One is always horizontal, while the other one is vertical. You will then put the gears on the tip of the vertical and the center of the horizontal one. The two turbines rotate in the opposite direction to each other.
It will then create an entrapment in the shape of a crescent gap between the gear and the housing. To obtain accurate measurements with these meters, you need to keep the gears small and slip between the housing.
Liquid positive displacement meters
It is a type of mechanical flow meter with a nutating disc. They are the most popular PD meters, which are essential for residential water meters. When water passes through the metering chamber, it will make the disk nutate. This will, in turn, lead to the spindle turning, which causes the magnetic rotation.
The magnet is characterized by the transmission of pulse or automatic registration. The flow rate is always proportional to the rotational velocity of the spindle. It is because the meter catches up to a fixed quantity of fluids every time the spindle rotates.
Piston meters
Piston meters are one of the mechanical flow meter types that are common in viscous liquids like the metering of oil in engine test stands. You can also use piston meters to measure residential water where less dirt can pass through the pipe or channel.
Helix meters
A positive displacement meter continuously uses a pair of radially pitched helical gears to catch up with the fluid flow. The fluid flow will lead to the enforcement of the rotation of the helical gear in a pipeline plane. The pulse train from the magnetic or optical sensors is usually proportional to the rotation speed of the helical gear.
Other mechanical flow meter types include:
- Metering pumps
- Gas PD meters
- High precision PD systems
Advantages of mechanical flowmeters
Some of the advantages of mechanical flow meters include:
1. Mechanical flow meters are relatively cheaper during the first installation process.
2. Mechanical flow meters are very reliable and provide the most accurate results on measurements.
3. Mechanical flow meters require low inline maintenance
Disadvantages of mechanical flowmeters
Some of the disadvantages of mechanical flow meters include:
1. Mechanical flow meters have a shorter life service.
2. The parts of a mechanical flow meter can be damaged. Therefore you need to do regular accuracy testing.
3. Mechanical flow meters may have some head loss.
4. Mechanical flow meters are always prone to wear because of silty water. It may, in turn, lead to inaccuracy where you’ll have to replace the moving parts more frequently.
Final words
Mechanical flow meters are always effective when it comes to the measurement of flow. There are different types of mechanical flow meters that you can use. However, the type of your application will determine which mechanical flow meter to use.
