Tub Grinder Output Size and Throughput Checks for Orchard Prunings

Tub grinder throughput for orchard prunings should describe accepted output over a defined time, not simply how fast branches disappear into the machine. A commissioning test needs to show both particle-size suitability and production under documented feed conditions. This guide gives the project owner and receiving customer a shared test sheet so that a fast run cannot conceal excessive oversize, repeated passes or long handling delays.

Agree on acceptance before the trial starts

Write down the destination’s output requirements, sampling method and decision process. Identify who accepts or rejects a lot and what happens when a sample is outside the agreed limits. If the receiving customer has not supplied an acceptance rule, report the observed output characteristics without calling the material contract-compliant. A screen opening on the grinder is a machine configuration, not proof of the entire discharged particle-size distribution.

Link these requirements to the project brief established in the orchard biomass processing selection guide. Keep the same branch sources, preparation boundaries and intended outlet in the commissioning record. When any of those assumptions changes, identify the change instead of treating the new run as directly equivalent.

Identify and measure the trial lot

Label the incoming material by orchard source, pruning operation, collection date and storage condition. Record representative branch geometry, leaf content and the inspection that released it for processing. Use measured net mass where available, and state the weighing method. If only loose volume is available, retain that unit and describe the measurement; do not convert it to tonnes using an unrelated density.

Check the moisture-reporting basis where moisture is measured. Wet input mass includes water, so different moisture conditions can complicate comparisons between lots. Keep the measurement method and timing with the result. The test does not need an invented moisture value to look complete: an explicitly unmeasured condition is more honest than a precise number inferred from appearance.

Keep two clocks and an event log

Define active processing time and total elapsed trial time separately. Use the agreed start and finish events consistently for each lot. Record loader waiting, preparation, discharge clearing, inspection, adjustments and other interruptions against timestamps. Never delete an interruption from the elapsed record merely because it is inconvenient for the reported rate. It may explain the actual system constraint.

Keep setup and transport outside the active-processing clock but visible in the broader project schedule. A commissioning result should state exactly which tasks its denominator includes. If a supplier reports a rate from a short stable segment, retain that segment as a separate observation rather than replacing the complete-lot result with it.

Measure discharged material and accepted material separately

Collect output samples using the agreed procedure, from safe locations and without approaching operating discharge equipment. Identify each sample by lot and run. Record the actual machine configuration, including the screen and any authorized changes between runs. Inspect the sample through the destination’s assessment method rather than judging the whole lot from a single photograph.

Keep accepted output, oversize, rejects and material waiting for another pass in distinct record fields. If material is recirculated, identify it as the same material receiving additional processing. Do not count its second passage as fresh input. Track the added time and final accepted quantity so the final result remains a measure of useful production.

A worked denominator example

The following numbers are illustrative arithmetic only, not WeiDong machine performance. Suppose a completed trial produces 8 tonnes of accepted output during 2 hours of active processing, within a 3-hour elapsed trial window. The active accepted-output rate is 4 tonnes per active hour. The elapsed accepted-output rate is about 2.67 tonnes per elapsed hour. Both figures can be correct, but they answer different planning questions.

If some discharged material still awaits acceptance, do not count it in the accepted total until the decision is made. If another pass is required, add the associated time to the relevant totals and count the accepted mass once. Report incomplete measurements as incomplete; do not force an exact mass balance when scales, stock carryover or moisture changes have not been reconciled.

Test field	Recorded evidence	Why it matters
Input boundary	Lot identity, mass or volume method, preparation and condition	Defines what the machine actually received
Time boundary	Active and elapsed clocks with interruption events	Separates machine activity from complete-lot delivery
Output decision	Sample identification, assessment and accepting person	Distinguishes discharged material from usable product
Repeat processing	Returned material, extra passes and extra time	Prevents double counting and hidden rework

Repeat before extending the result

Repeat the trial across representative permitted lots and retain the range of results. A single favorable run cannot establish performance for all orchard species, branch forms or storage conditions. When comparing configurations, change only the planned variable where practical and document unavoidable differences. Follow the manufacturer’s shutdown, isolation and adjustment procedures; this measurement guide does not authorize adjustments during operation.

The compost-feedstock output checking guide uses the same distinction between discharge and acceptance, while the mobile orchard project-fit review adds the transport and setup boundaries that a short trial does not capture.

Close the commissioning record

Attach the signed test sheet, sample results and unresolved items to the chosen tub grinder configuration. Use the horizontal wood grinder overview only as another layout reference, not as a substitute for testing. Send the complete record through the project contact page when requesting a configuration review or follow-up trial. The strongest result states both what the test demonstrated and where its evidence stops.