Holmen Pellet Durability Testers : Frequently Asked Questions…

Everything you need to know about Holmen Pellet Durability Testers manufactured by TEKPRO, including how they work, what Pellet Durability Index (PDI) means, and the differences between the NHP100, NHP200 Series 2, and NHP300 systems.

What is a Holmen Pellet Durability Tester?

A Holmen Pellet Durability Tester is a machine designed to measure the durability of pellets by calculating their Pellet Durability Index (PDI). The Holmen range provides a fast and reliable method for testing feed and wood pellets and is used worldwide as a quality control tool for pellet production.

What does PDI stand for?

PDI stands for Pellet Durability Index.

It is a measurement used to determine how well pellets withstand handling and transportation. A higher PDI generally indicates that pellets are more resistant to breaking down into fines during movement from production through to final use.

How does the Holmen testing method work?

The Holmen method simulates the stresses pellets encounter during transport and handling.

During testing, pellets are agitated in a controlled airstream at a fixed pressure. The pellets collide with each other and with the test chamber surfaces, replicating real-world handling conditions. The amount of pellet degradation is then used to calculate the durability result.

Why is pellet durability important?

Pellet durability is an important indicator of pellet quality.

Durable pellets can help reduce:

• Excess fines
• Product wastage
• Handling losses
• Quality variation reaching the end user

Durability testing also allows mills to monitor production quality and optimise manufacturing processes. 

What Holmen models are available?

The Holmen range includes:

NHP100 Portable Pellet Durability Tester

A manual, portable system designed primarily for animal feed pellets.

NHP200 Series 2 Pellet Durability Tester

A semi-automatic laboratory system suitable for feed and wood pellets.

NHP300 Production Line Pellet Durability Tester

An automated inline system that extracts and tests samples directly from the production line.

What is the Holmen NHP100?

The NHP100 is TEKPRO’s entry-level pellet durability tester.

Key features include:

• Portable design
• Fast and simple operation
• Suitable for animal feed pellets
• Adjustable test time
• Results obtainable significantly faster than a traditional tumbling can method
• Available with different mesh hopper sizes

The NHP100 requires the operator to manually weigh pellets before and after testing to calculate PDI. 

Who should use the NHP100?

The NHP100 is ideal for:

• Feed mills
• Quality control teams
• Facilities requiring portability
• Operations testing pellets at multiple locations

Its lightweight and transportable design makes it suitable for users who need testing flexibility.

What is the Holmen NHP200 Series 2?

The NHP200 Series 2 is TEKPRO’s flagship pellet durability tester.

It is a semi-automatic desktop system designed for laboratories and busy testing environments where repeatable, accurate results are essential. 

What are the advantages of the NHP200 Series 2?

Key benefits include:

• Suitable for feed and wood pellets
• Reduced operator involvement
• Automatic weighing and PDI calculation
• Colour LCD touchscreen
• Data recording and storage
• Ethernet connectivity
• Daily result reporting capability
• Digital self-calibration
• Dedicated fines calculation feature
• Reproducible accuracy of ±0.1%

The automated process helps minimise the possibility of human error.

 How long does an NHP200 test take?

The average NHP200 Series 2 test takes approximately four minutes.

The machine automatically selects the appropriate test duration based on the user input pellet diameter.

What pellet sizes can the NHP200 test?

The NHP200 Series 2 is designed for pellets ranging from 3 mm to 12 mm diameter.

What is the Holmen NHP300?

The NHP300 is a fully automated production-line pellet durability testing system.

It is designed for highly productive mills where pellet quality must be monitored continuously with minimal manual intervention

How does the NHP300 improve production monitoring?

The system automatically:

1. Extracts samples from the production line
2. Performs durability testing
3. Displays and records results
4. Communicates with software systems

After testing, samples are discharged into a waste container.

Who is the NHP300 designed for?

The NHP300 is best suited to:

• Large feed mills
• High-capacity pellet plants
• Facilities seeking automation
• Operations integrating quality data into mill management systems

Can Holmen testers be used for wood pellets?

Yes.

The NHP200 Series 2 is suitable for both feed and wood pellets. TEKPRO also offers the Ligno-Tester, a portable durability tester adapted specifically for wood pellets.

What makes Holmen testers different from traditional tumbling can methods?

Compared to the tumbling can method, Holmen testers provide:

• Faster testing
• High repeatability
• Consistent results
• Reduced operator workload
• Improved quality monitoring

The NHP100 and NHP200 are both presented as quicker alternatives to traditional tumbling can testing methods.

 Are Holmen testers used internationally?

Yes.

Holmen Pellet Durability Testers are used around the globe and have become known for their speed, repeatability, and consistency of results.

Which Holmen tester is right for me?

Where are Holmen Pellet Durability Testers manufactured?

Holmen Pellet Durability Testers are designed and manufactured exclusively in the United Kingdom by TEKPRO Ltd.

The Holmen range has been developed through more than 15 years of involvement in the pelleting industry and is manufactured by TEKPRO under licence from Borregaard.