What is a Flowmeter? Types and Working Principles of Each Type

A flowmeter is a measuring instrument used to determine the flow rate of liquids, gases, or steam as they pass through a measurement point such as a pipe or open channel. It displays values as volumetric flow rate (e.g., cubic meters per hour, liters per minute) or mass flow rate (e.g., kilograms per second). Flowmeters play a crucial role in improving process accuracy, saving energy, and maintaining product quality.

There are many types of flowmeters, each with different working principles and suitable applications. As a distributor of high-quality measurement instruments from leading brands, ACTCOM2000 will guide you through the essentials.

Flowmeter Types and Their Working Principles

Flowmeters come in various types, each using different technologies suitable for different applications:

1. Electromagnetic Flowmeter

Works based on Faraday’s Law of Electromagnetic Induction. The device generates a magnetic field. When an electrically conductive fluid (such as water, wastewater, or chemicals) flows through this field, a voltage is induced, which is proportional to the flow velocity.

Suitable for: Electrically conductive liquids only (cannot measure deionized water, oil, or gases). It has no obstruction in the flow path.

2. Ultrasonic Flowmeter

Uses high-frequency ultrasonic waves transmitted across the fluid.

Two main measurement methods:

• Transit-Time: Measures the difference in travel time of ultrasonic waves moving with and against the flow.

• Doppler: Measures frequency shifts from waves reflected off bubbles or particles in the fluid.

Advantages: Can be installed as a clamp-on device (attached outside the pipe) without cutting the pipe—easy to install and maintain.

3. Coriolis Mass Flowmeter

Works based on the Coriolis Effect. The measuring tubes vibrate, and when fluid flows through, the tubes twist slightly. Sensors measure this twist to calculate the mass flow rate.

Features: Among the most accurate flowmeters; can measure mass flow, density, and temperature. Commonly used where high precision is required (chemical dosing, food & beverage, pharmaceuticals).

4. Turbine Flowmeter

A rotor with blades is installed inside the pipe. When the fluid flows, it spins the turbine, and the rotation speed is proportional to the flow rate.

Best for: Clean, low-viscosity fluids like fuels or clean water. Moving parts may wear or clog.

5. Variable Area Flowmeter (Rotameter)

A simple, visual flowmeter. It has a tapered transparent tube and a floating element. As fluid flows upward, it lifts the float until forces balance.

Use: For applications requiring general flow indication rather than high accuracy.

6. Vortex Flowmeter

Works based on vortex shedding. A bluff body placed inside the pipe creates alternating vortices as fluid flows past. The frequency of vortex formation correlates with the flow rate.

Suitable for: Liquids, gases, and especially steam.

7. Differential Pressure (DP) Flowmeter

Measures pressure differences created when fluid flows through a restriction such as:

• Orifice Plate

• Venturi Tube

Based on Bernoulli’s Principle—higher velocity leads to lower pressure.

A long-established, widely used flow measurement method.

Industries That Use Flowmeters

Flowmeters are essential in automation, monitoring, cost control, and maintaining production quality. Common industries include:

• Water and wastewater treatment: Measurement of raw water, treated water, wastewater.

• Chemical and petrochemical: Chemical flow, solvents, fuels for process control.

• Food & beverage: Milk, juice, beer, syrup (requires food-grade equipment).

• Pharmaceuticals: Highly accurate dosing (Coriolis is widely used).

• Power plants and energy: Steam, natural gas, cooling water.

• HVAC systems: Chilled water flow in large buildings.

Parker Flowmeters and Flow Controllers

Choosing the right flowmeter is crucial. Parker provides high-quality flow control instruments including flow tubes, metering valves, and flowmeters.

Gas Mass Flow Controllers

• Ranges: 0–5 sccm to 0–1000 slpm

• Fast response (<1 second)

• High accuracy (up to 1% of reading)

• Analog & digital communication (ModBus, ProfiBus, DeviceNet)

Variable Area Purgemeter

• Scale lengths: 65 mm and 150 mm

• Replaceable tubes and valves without removing the device from the system

LC223S – High-Pressure Flow Controller

• For high-pressure liquids or gases

• Used in liquid chromatography, chemical injection

• Maintains stable flow despite downstream pressure variations

SC423XL – Sampling Flow Controller

• For air sampling and analytical systems

• Precise low-flow control (as low as 1 sccm)

• Stable under wide temperature and vacuum conditions

VCD-1000

• Linear relationship between knob rotation and flow rate

• Ranges: 5 sccm to 1,500 sccm

Severe Duty Gas Mass Flow Controllers

• NEMA 4X / IP66, hazardous area certified (Class 1, Div. 2, ATEX Zone 2)

• Ranges: 100 sccm to 100 slpm

Acrylic Flowmeters

• Acrylic flow tubes

• Connection materials: brass, PVC, or stainless steel

Glass Tube Flowmeters

• 35 flow ranges in 6 tube sizes

• Optional alarm signal

Metal Tube Variable Area Flowmeters

• Materials: 316SS, Monel®, Hastelloy®

• Optional alarm and 4–20 mA output

ACTCOM2000 – Your Authorized Parker Flowmeter Distributor

We supply and support Parker Flowmeters and Flow Controllers.

Contact us: LINE: @Actcom2000 Phone: 02 944 4748