Reliable Low-Flow Measurement with Simple Rotameter Design

The Yokogawa RAGL Laboratory Rotameter is a variable area flowmeter designed for measuring low flow rates of liquids and gases.

Unlike electronic flowmeters, RAGL uses a simple mechanical measuring principle. A float moves inside a vertically installed conical glass tube as the flow changes, and the flow rate can be directly read from the scale on the tube.

This simple structure provides reliable measurement without external power supply, making it suitable for applications where easy operation, visual monitoring, and low maintenance are important.

How Does the RAGL Rotameter Work?

The RAGL uses the traditional variable area flow measurement principle.

When fluid enters the bottom of the vertical measuring tube, the float rises until the upward force from the flow balances the weight of the float.

The position of the float indicates the current flow rate, allowing operators to visually monitor the process directly from the glass tube.

This makes RAGL especially useful for applications where operators need immediate confirmation of flow conditions.

Designed for Laboratory and Small Flow Applications

The RAGL is optimized for low-flow applications where conventional industrial flowmeters may not be practical.

Typical applications include:

• Laboratory equipment
• Analyzer systems
• Gas sampling systems
• Purge systems
• Machinery equipment
• Process monitoring systems

Its compact design and wide range of available tubes and floats allow the meter to be configured for different flow requirements.

Transparent Glass Tube for Direct Observation

One of the main advantages of a glass rotameter is the ability to visually observe the flow condition.

The transparent borosilicate glass measuring tube allows operators to:

• Confirm whether flow exists
• Monitor changes immediately
• Identify abnormal conditions visually
• Adjust flow manually when required

This direct indication makes RAGL a practical choice for local flow monitoring applications.

Low Pressure Loss and No External Power Required

The RAGL design provides:

• Low pressure loss
• Local mechanical indication
• No electrical power requirement
• Simple installation and operation

For applications where only local flow indication is needed, a rotameter can provide a cost-effective alternative to powered flow measurement instruments.

Optional Needle Valve for Precise Flow Adjustment

The RAGL can be equipped with optional integrated needle valves.

These valves allow operators to manually adjust and control flow, which is especially useful in:

• Gas purge systems
• Analyzer sample conditioning
• Laboratory test equipment
• Calibration setups

The valve provides finer adjustment compared with using an external control valve.

Replaceable Glass Tube Design

The special RAGL construction allows the glass tube to be replaced without removing the complete instrument from the installation.

This helps simplify maintenance and reduces downtime when the measuring tube requires replacement.

Wide Selection of Measuring Tubes and Floats

The RAGL is available with different measuring tube designs and float materials to match different flow ranges and media conditions.

Available options include:

• Different cone designs
• Different float materials
• Various scales
• Different connection options
• Optional limit switches
• Optional flow controllers

This flexibility allows the rotameter to be adapted to specific laboratory and process requirements.

Key Features

• Variable area flow measurement principle
• Measurement of liquids and gases
• Transparent borosilicate glass measuring tube
• Direct visual flow indication
• Non-powered operation
• Suitable for low-flow applications
• Low pressure loss
• Compact laboratory design
• Optional integrated needle valves
• Optional limit switches for alarms
• Replaceable glass tube design
• Multiple float materials available
• Multiple connection options
• ATEX approval available
• Suitable for IEC 61508 and ISO 13849 applications

Technical Highlights

• Pipe Size: 1/4 inch to 3/8 inch
• Measurement Range:Water (20 °C): 2 ml/h to 600 l/hAir (20 °C, 1 bar abs.): 0.1 l/h to 6300 l/h
• Process Connection: Threaded, Swagelok, cutting ring, nozzle
• Wetted Materials: Borosilicate glass, 1.4571 stainless steel, polypropylene
• Process Temperature: -25 °C to +130 °C
• Maximum Pressure: 16 bar
• Accuracy: Up to 1.6% according to VDI/VDE 3513-2

Typical Applications

Analyzer Systems

RAGL is commonly used in analyzer systems where a stable and visible sample flow is required.

Gas Sampling

For gas sampling systems, the rotameter provides simple flow monitoring without requiring additional power or complex electronics.

Purge Systems

The RAGL is suitable for purge applications where maintaining a small continuous flow is important.

Laboratory Equipment

The compact design makes it suitable for laboratory and research equipment requiring accurate low-flow indication.

Machinery Equipment

RAGL can be integrated into machinery where operators need simple local monitoring of liquid or gas flow.

FAQ

What is the Yokogawa RAGL Rotameter?

The Yokogawa RAGL is a glass variable area flowmeter designed for measuring low flow rates of liquids and gases. It uses a float inside a conical glass tube to provide direct visual flow indication.

Does the RAGL require power supply?

No. The standard RAGL provides local mechanical indication and does not require electrical power.

What fluids can the RAGL measure?

The RAGL is designed for measuring liquids and gases, including applications such as purge systems, analyzer systems, and gas sampling systems.

What is the measurement principle of a rotameter?

A rotameter uses the variable area principle. The float rises or falls inside a tapered tube according to the flow rate, and the float position indicates the measured flow.

Why choose a glass rotameter instead of an electronic flowmeter?

A glass rotameter provides simple operation, direct visual indication, no power requirement, and low maintenance. It is often preferred for small flow applications where advanced electronic functions are unnecessary.

Can the RAGL measure very small flow rates?

Yes. The RAGL is designed specifically for low-flow measurement applications and can measure very small liquid and gas flows depending on the selected tube and float configuration.

Can the RAGL be used for gas measurement?

Yes. Gas measurement is one of the main applications of the RAGL laboratory rotameter.

Does RAGL have a control valve?

Optional needle valves can be integrated into the inlet or outlet side for fine flow adjustment.

Is the glass tube replaceable?

Yes. The RAGL design allows replacement of the glass tube without removing the complete device from the installation.

What is the maximum pressure of RAGL?

The maximum process pressure is 16 bar.

What is the maximum temperature of RAGL?

Depending on configuration, the process temperature can reach up to +130 °C.

Where is RAGL commonly installed?

Typical installations include laboratories, analyzer panels, gas sampling systems, purge systems, and machinery equipment.