Pellet diameter is only one geometric input to a fuel-handling system. Length distribution also matters: an isolated long pellet, a high share of short pieces or an inconsistent lot can interact differently with screws, rotary valves, gates and dosing units. A European buyer should therefore turn “pellet length” into a measurable purchase and acceptance requirement rather than approve a shipment from the nominal diameter alone.
Nord Panels manufactures wood pellets in Kazakhstan using only Kazakhstan-sourced raw materials. The checks below are a procurement framework; they do not state that a product is certified to a particular scheme.
Separate diameter from length distribution
A 6 mm or 8 mm diameter does not describe how long the pieces are. Record at least three different facts:
- nominal diameter;
- the agreed length interval and any overlength limit;
- the share of short pellets, using an agreed threshold and reporting basis.
This separation prevents a diameter declaration from being treated as proof of full feed-system compatibility. It also gives production, logistics and receiving teams the same vocabulary when they investigate an interruption.
Use current standards as measurement references
ISO 17829:2025 specifies methods for pellet diameter and length, including fractions above 40 mm, particles below 10 mm and average length. ISO 17225-2:2021 defines specifications and quality classes for graded wood pellets for non-industrial and industrial use.
For ENplus-certified pellets, the current ENplus ST 1001 second edition, effective from 1 January 2026, uses 3.15–40 mm as the stated length range, permits no more than 1% by mass above 40 mm and permits no pellet above 45 mm. It also introduces reporting categories for the share below 10 mm. Treat these values as scheme-specific references: do not claim ENplus conformity unless the exact product and supply chain are covered by valid evidence.
Map the buyer’s actual feed path
Identify the restriction points
Ask the equipment supplier or plant engineer to review the complete path: receiving connection, silo outlet, agitator, screw conveyor, rotary valve, transfer chute, day bin and burner dosing unit. The narrowest opening is not the only risk; changes in direction, low-clearance gates and intermittent starts can be equally relevant.
Define the symptom that must not occur
Use observable acceptance language such as “no persistent bridging at the day-bin outlet,” “no unplanned auger stop during the trial” or “stable dosing within the equipment manufacturer’s operating window.” Do not substitute a generic promise that the pellets “flow well.”
Request lot-relevant evidence
A useful pre-order file states the sampling point, sampling date, test method, sample size, measured share above the agreed upper threshold and the share below the agreed short-length threshold. Confirm whether the evidence represents production, loading or receipt. Handling can change the distribution, so a production result and an arrival result are not automatically interchangeable.
For a new combination of fuel and equipment, retain a sealed reference sample and approve a controlled trial before scaling up. Record hopper level, feed rate, start-stop cycles, alarms and visible accumulation at transfer points.
Put the decision into the contract
A concise purchasing clause can include:
- nominal diameter and agreed length distribution;
- named sampling and test method;
- maximum overlength share and absolute maximum piece length;
- reporting rule for short pellets;
- sampling point and lot definition;
- trial quantity and equipment configuration;
- acceptance, hold and retest process.
Avoid copying certification limits into a contract without confirming that the intended class, delivery form and end-use apply. The buyer’s equipment manual and risk assessment remain decisive.
Questions to send with the RFQ
- Which length method and edition will be used?
- What are the measured overlength and short-length shares for the offered lot?
- Where and when was the sample taken?
- Can a representative trial lot be supplied before the volume order?
- Which documents will accompany each shipment?
- How will an out-of-limit result be isolated and retested?
Share the feed-system description, target diameter, delivery format and required evidence through the Nord Panels contact page. A clear length specification makes supplier comparison more defensible and reduces the chance that a geometry mismatch appears only after unloading.