Redwood Viscometer vs Saybolt Viscometer: Which One Should You Use?

When it comes to measuring the viscosity of petroleum products and industrial fluids, choosing the right viscometer is critical for accuracy, compliance, and process efficiency. Two of the most widely used instruments are the Redwood Viscometer and the Saybolt Viscometer. While both are designed to measure fluid flow characteristics, their applications, standards, and suitability differ.

In this guide by Heico Dynamics, we break down the differences, advantages, and ideal use cases to help you decide which viscometer you should use.

What Is a Redwood Viscometer?

A Redwood Viscometer is a standard laboratory instrument used to determine the viscosity of petroleum oils, lubricants, and fuel oils at specific temperatures. It measures the time taken for a fixed volume of liquid to flow through a standardized orifice.

There are two main types:

• Redwood No. 1 Viscometer, used for low-viscosity fluids

• Redwood No. 2 Viscometer, used for high-viscosity fluids

Key applications include lubricant testing, fuel oil analysis, and quality control in oil refineries.

What Is a Saybolt Viscometer?

A Saybolt Viscometer is primarily used to measure the viscosity of petroleum products, oils, and chemicals using the Saybolt Universal Seconds method. It is commonly used in industries that follow ASTM standards, especially in the United States.

Saybolt viscometers are classified into:

• Saybolt Universal Viscometer, for low to medium viscosity fluids

• Saybolt Furol Viscometer, for highly viscous materials

Redwood Viscometer vs Saybolt Viscometer: Key Differences

1. Measurement Standard

The Redwood viscometer follows British standards, while the Saybolt viscometer follows ASTM standards. This makes the choice highly dependent on regulatory or client requirements.

2. Units of Measurement

• Redwood Viscometer measures time in Redwood Seconds

• Saybolt Viscometer measures time in Saybolt Universal Seconds (SUS)

3. Application Regions

Redwood viscometers are more commonly used in India, the UK, and Commonwealth countries, while Saybolt viscometers are widely used in North America and global ASTM-compliant labs.

4. Viscosity Range

Redwood No. 2 and Saybolt Furol are both suitable for high-viscosity fluids. However, Saybolt instruments offer slightly better flexibility for ASTM-based testing environments.

Which Viscometer Should You Use?

Choose a Redwood Viscometer if

• You work with petroleum oils or lubricants

• Your testing follows British or Indian standards

• You require simple, reliable viscosity measurement

• Your lab focuses on fuel oil and lubricant quality control

  
  

Choose a Saybolt Viscometer if

• Your testing follows ASTM viscosity standards

• You export products to international markets

• You need standardized results in Saybolt Universal Seconds

• You test a wide range of petroleum-based fluids

Accuracy, Reliability, and Maintenance

Both viscometers provide excellent accuracy when properly calibrated and maintained. However, choosing a high-quality instrument from a trusted manufacturer like Heico Dynamics ensures:

• Consistent and repeatable results

• Durable construction for long-term use

• Compliance with industry standards

• Easy maintenance and reliable after-sales support

Cost vs Performance Consideration

In terms of investment, both viscometers are cost-effective solutions for routine viscosity testing. The real value lies in choosing the right instrument that matches your industry standards, testing frequency, and compliance needs. Selecting the wrong viscometer can lead to inaccurate reporting and regulatory issues.

Conclusion

Both the Redwood Viscometer and Saybolt Viscometer are reliable tools for viscosity measurement, but the right choice depends on testing standards, application requirements, and regional compliance.

If your laboratory follows British or Indian standards, the Redwood Viscometer is the ideal choice. If ASTM compliance is required, the Saybolt Viscometer is the better option.

Heico Dynamics offers precision-engineered viscosity testing equipment designed for accuracy, durability, and compliance. Choosing the right viscometer today ensures better quality control and confident decision-making tomorrow.