How do I size a destoner?

Match its wheat capacity to your cleaning line throughput with 30% margin. A 30 t/d plant cleaning at 5 t/h needs a TQSF100 (7–9 t/h) rather than a TQSF60 (3–5 t/h).

What is the difference between TQSF125 and TQSFB4125?

The B variant uses a larger air volume and a steeper deck to reach 15–18 t/h on the same 125 cm screen width, versus 9–11 t/h for the standard version.

How do I know if my destoner is working?

Take a 1 kg sample from the stone outlet. It should be almost entirely stones. More than 10 wheat kernels per 100 stones means the air volume is too high or the deck angle is wrong.

Cluster article

Gravity Destoner Selection Guide: Sizing, Air Volume and the 95% Test

How to size a gravity destoner for a flour mill, why the same screen width carries two very different capacities, and a simple field test to verify 95% stone removal.

By Haiyun engineering desk Updated 2026-11-07 7 min read

Key takeaways

Destoners are sized on wheat capacity in t/h, not screen width — the same width has B variants with 60% more capacity.
Air volume, deck angle and amplitude must be tuned together; changing one alone destroys separation.
Verify performance quarterly with the 200-stone spike test — anything below 95% removal means re-tuning or screen replacement.

Why the destoner is the machine people get wrong

Screens are intuitive: wheat passes over holes, small things fall through. Destoners are not. They separate particles of the same size by density, using a fluidised bed created by air passing up through a vibrating deck.

Three parameters are coupled:

Parameter	Effect
Air volume	Fluidises the bed; too little and nothing separates, too much and wheat blows out with the stones
Deck amplitude	Agitates the bed; too little and it does not stratify
Deck angle	Controls residence time and stone travel direction

Change one and you must re-tune the other two. This is why destoners are often found running badly — someone adjusted the air “to stop blowing wheat out” and never re-tuned the rest.

The two capacity families

Haiyun’s TQSF range has two families on overlapping screen widths:

Model	Screen width	Capacity (wheat)	Air volume
TQSF60	60 cm	3–5 t/h	4,500 m³/h
TQSF80	80 cm	5–7 t/h	6,000 m³/h
TQSF100	100 cm	7–9 t/h	8,000 m³/h
TQSF125	125 cm	9–11 t/h	10,200 m³/h
TQSFB4125	125 cm	15–18 t/h	12,000 m³/h
TQSF150	150 cm	11–14 t/h	12,000 m³/h
TQSFB150	150 cm	18–20 t/h	15,000 m³/h
TQSF175	175 cm	14–18 t/h	15,000 m³/h
TQSF200	200 cm	16–20 t/h	17,000 m³/h
TQSF250	250 cm	20–22 t/h	20,400 m³/h

Note the bold rows: TQSFB4125 delivers 64% more capacity than TQSF125 on the identical 125 cm width. The difference is air volume and deck geometry.

When to choose a B variant: when floor space is the constraint rather than headroom, or when you are retrofitting a higher-capacity line into an existing building.

When not to: B variants need 20% more air, which means a larger fan and more power. If space is available, the standard model is more efficient per tonne.

Sizing rule

Destoner capacity ≥ 1.3 × cleaning line throughput

A 30 t/d plant with cleaning at 5 t/h needs 6.5 t/h of destoner capacity → TQSF100.

Do not size on mill throughput. Cleaning runs ahead of milling, and during harvest intake the line may run at 1.5× nominal for hours.

Air supply

The destoner’s fan is usually supplied with the machine, but check:

Static pressure must match the deck resistance at the specified air volume
Duct length beyond 3 m adds pressure drop and reduces effective volume
Air quality — dusty recirculated air blinds the deck and reduces fluidisation

If you share a fan with other equipment, verify the destoner still gets its rated volume. Shared fans are a common cause of poor destoning.

The 95% field test

Quarterly, do this:

Count out exactly 200 clean field stones (or glass beads of similar size)
Mix them into 20 kg of clean wheat
Run the wheat through the destoner at production rate
Collect and count stones in the stone outlet and in the accepted wheat

Target: 190+ stones in the stone outlet, fewer than 10 in the accepted wheat (95% removal).

Results and actions:

Removal rate	Action
> 97%	Excellent
95–97%	Acceptable
90–95%	Re-tune air volume and deck angle
< 90%	Inspect screen cloth for wear or holes; replace if needed

Wheat loss in the stone outlet should be under 10 kernels per 100 stones. More than that means the air volume is too high and you are blowing good wheat out with the stones.

Maintenance

Item	Interval
Deck screen inspection	Weekly
Screen replacement	When holes or wear exceed 10% of area
Air volume check	Monthly
Fan bearing grease	500 hours
Suspension springs	Annual inspection

The deck screen is the wearing part. A hole in the deck lets wheat fall into the stone channel, which shows up as high wheat loss in the stone outlet — a symptom often misdiagnosed as excessive air.