Flow Controllers

Flow controllers are components used to measure and regulate the flow rate of liquids or gases in a system. They combine a flow meter with a control valve to maintain a specified flow rate, even with fluctuations in pressure or other process conditions. Flow controllers are crucial in various industries where precise fluid management is essential for process control, quality assurance, and safety.

What is a Flow Controller?

A flow controller, also referred to as a flow regulator or "mass flow controller", is a device that accurately measures and controls the flow of liquids and gases. These devices are designed to regulate a specific type of gas or liquid at a particular range of flow rates, using an electrical signal for precise control.

The electric signal allows the flow controller to automatically set the flow rate, independent of external conditions or changes in pressure. Mass flow controllers are widely used in various industrial applications where precise and reliable flow control is essential.

How Does a Flow Controller Work?

A flow controller typically consists of a sensor, a bypass, a control valve, and control circuitry. The medium enters from the inlet and flows through the sensor or the bypass. The sensor then detects the mass flow rate as a change in temperature, which is then converted into an electric signal. This signal is processed by the amplification, correction, and comparison control circuits and output as a voltage reading (e.g. 5V).

The comparison control circuit compares the flow rate setting (desired flow rate) with the actual flow rate measured by the sensor. It then sends the difference between the two readings to the valve driving circuit, adjusting the valve position to match the actual flow rate to the desired setpoint. This feedback loop ensures that the flow controller maintains the correct flow level.

Flow Controller Types

Mass flow controllers can be categorised based on their underlying measurement and control principles:

Thermal Flow Controllers

Thermal flow controllers utilise the thermal properties of the fluid to measure and control the mass flow rate. These controllers are commonly used for clean and dry gas applications.

Coriolis Flow Controllers

Coriolis flow controllers work by using a direct relationship between mass flow rate and mass inertia for various fluid mixtures.

Ultrasonic Flow Controllers

Ultrasonic flow controllers rely on ultrasonic waves. The sensors measure the flow velocity and multiply them by the device’s tube cross-section to derive and control the volumetric liquid flow rate.

Positive Displacement Flow Controllers

Positive displacement flow controllers work via a mechanical mechanism, such as a gear pump, to measure and control the volumetric flow rate of liquids.

Gas Flow Controller

Gas flow controllers, also known as gas mass flow controllers, are specifically designed to regulate the flow of gases in various applications. They offer precise control over the gas flow rate, ensuring accurate delivery and maintaining consistent process conditions.

Gas flow controllers are commonly used in industries such as pharmaceuticals, chemical processing, and semiconductor manufacturing, where precise gas control is critical for product quality and process efficiency.

Water Flow Controller

Water flow controllers, also known as liquid mass flow controllers or water flow regulators, are designed to regulate the flow of water in various applications. They typically utilise a pressure-compensating mechanism, often involving an O-ring, to maintain a constant flow rate even with fluctuations in water pressure.

Water flow controllers are commonly used in residential and commercial settings to conserve water, reduce water bills, detect water damage, and improve the efficiency of plumbing systems.

Key Features of a Flow Regulator

Sensor

The sensor is a central component of an electronic flow controller. It consists of a thin capillary tube, often in stainless steel, wrapped in a resistor. When gas passes through, the temperature change provides feedback to the control circuitry for precise regulation.

Bypass

Located downstream of the sensor, the bypass is a thin circular slat or cone. It uniformly diffuses gas flow inside the instrument to calculate the total flow in relation to the sensor flow.

Flow Rate Control Valve

The flow rate control valve is responsible for adjusting the flow rate according to the setpoint. It can be a digital or electronic valve, depending on the design and application.

Seals

Seals are essential for preventing leaks and maintaining the integrity of the flow control system. They ensure that the fluid is contained within the flow controller and does not escape into the surrounding environment.

Circuitry

The circuitry within a digital mass flow controller processes the signals from the sensor, compares them to the setpoint, and controls the valve to achieve the desired flow rate.

Benefits of Flow Rate Controllers

Mass flow controllers offer numerous benefits, including:

• Cost-effectiveness
• Consistent pressure maintenance
• Reduced air consumption
• Lower utility bills
• Environmental efficiency
• Up to 85% water conservation
• Durable and long-lasting

Industrial Applications of Flow Controllers

Pharmaceuticals

Flow controllers are critical in pharmaceutical manufacturing for precise dosing of liquids and gases in various processes, such as drug formulation, mixing, and packaging.

Aerospace

In aerospace applications, flow controllers are used for precise fuel and gas management, ensuring optimal engine performance and fuel efficiency.

Food and Beverage Production

Flow controllers are used in food and beverage production for accurate mixing, blending, and filling operations, ensuring consistent product quality and reducing waste.

Semiconductor Manufacturing

Flow controllers play a critical role in semiconductor manufacturing for precise gas delivery in various processes, such as chemical vapor deposition (CVD).

Environmental Monitoring

Flow controllers are used in environmental monitoring equipment for accurate measurement and control of gas flows, enabling precise analysis of air quality and emissions.

Difference between Mass Flow Controller and Mass Flow Meter

• Purpose: A mass flow controller is designed to both measure and control the mass flow rate of a fluid, while a mass flow meter only measures the flow rate without controlling it.
• Main parts: A mass flow controller includes a sensor, a control valve, and control circuitry, while a mass flow meter typically only has a sensor.
• Control: A mass flow controller can automatically adjust the flow rate to maintain a desired setpoint, but with high pressure loss. Conversely, a mass flow meter can only provide a reading of the current flow rate, but with lower pressure loss.

How to Select a Suitable Flow Regulator

Consider the following factors when selecting a flow controller:

• Inlet and outlet fittings: Ensure that the flow controller's inlet and outlet fittings are compatible with the size and type of your piping or tubing. For example, you should select the instrument with the largest inlet fittings compatible with the size of your intended process line.
• Ambient temperature of fluid: Consider the ambient temperature of the fluid being controlled, as this can affect the accuracy and performance of the flow controller.
• Maximum and minimum flow rate: Choose a flow controller with a flow rate range that encompasses the maximum and minimum flow rates required for your application.
• Flow body material: Select a flow body material that is compatible with the fluid being controlled to prevent damage or contamination. This is particularly vital if you’re dealing with corrosive substances.
• Location of flow controller: Consider the location where the flow controller will be installed, as environmental factors such as temperature, humidity, and vibration can affect its performance.

Trusted Flow Controllers Manufacturer, Supplier and Distributor in Australia

RS Australia is a trusted and leading manufacturer, supplier, and distributor of flow controllers from leading brands like SMC, Burkert, and Omron, providing customers with a comprehensive range of high-quality flow control solutions.

Beyond flow controllers, RS Australia also offers a wide range of other measurement instruments for your various project needs. Whether it’s a voltmeter, an infrared thermometer, or a manometer, you’ll find it in our extensive selection of products.

Buy Flow Rate Controller Online from RS Australia

Need a reliable flow rate controller? Shop on our user-friendly online platform and get your item delivered with our convenience delivery services. With flexible options like express and next-day deliveries, you can receive your flow controller quickly and efficiently wherever you are in Australia. Find out more about the delivery fees and options on our delivery information page.