InterProcess Sp. z o.o. | Rozwiązania dla przemysłu
What volumetric feeding is
Economy built on a constant volume per unit of time
Volumetric screw feeders are the most economical way to deliver bulk materials at a controlled rate. Unlike gravimetric systems, flow control here relies on regulating the rotational speed of the feeding element — either a auger screw with a centre shaft or a shaftless spiral. Thanks to a simple design with no weighing system, a volumetric screw feeder offers a lower capital cost while still providing feeding repeatability of ±2–4% of set value after calibration.
The DSL V family works equally well as a standalone feeding unit in continuous operation and as part of a batching system. Just as importantly, every DSL V volumetric feeder can be upgraded later to a full gravimetric (loss-in-weight) system by adding load cells and a controller — without replacing the feeder itself.
The DSL V feeder family
DSL35 V · DSL75 V · DSL150 V
Screw feeders in service — click to enlarge
The DSL V family of volumetric feeders comes in three sizes (DSL35 V, DSL75 V and DSL150 V), covering bulk materials of widely varying characteristics and particle size. The structure is built entirely from stainless steel and fitted with a horizontal agitator driven by its own motor, which keeps the metering screw evenly filled.
Throughput is regulated by the rotational speed of the feeding element — either a auger screw with a centre shaft or a shaftless spiral (helix). The two are freely interchangeable, extending the feeding range of a single unit.
Key specifications
- Accuracy
- max. error ±2–4% of set value after calibration
- Feed rate
- from 0.5 to 25000 l/h
- Turndown ratio
- 1:12 (min:max) on a single feeding element
- Feeding elements
- auger screw or spiral, ∅18–150 mm
- Hoppers
- trough 12.5–60 l, extension hoppers 30–2400 l
- Drive
- SEW gearmotor 3×400 V; options: 3×500 V, aseptic version, frequency inverter
- Agitator
- horizontal, driven by a separate motor
- Construction
- steel 1.4301 (AISI 304) or 1.4404 (AISI 316L)
- Finish
- electropolished or glass-bead blasted, continuous internal welds
- Options
- hygienic version, ATEX build, upgrade to a gravimetric system
- Intended use
- dry bulk materials — well-flowing and difficult-flowing, aerating, compressible
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Selecting the DSL V feeder size
Three trough sizes cover a feed rate range from 0.5 to 25000 l/h. Every feeding element gives a turndown ratio of 1:12 — full feed rate tables for the individual screw and spiral diameters are given in the datasheet.
| Model | DSL35 V | DSL75 V | DSL150 V |
|---|---|---|---|
| Feed rate range | 0.5–450 l/h | 7–5000 l/h | 70–25000 l/h |
| Feeding elements | ∅18–35 mm | ∅35–74 mm | ∅74–150 mm |
| Rotational speed | 10–250 rpm | 10–250 rpm | 10–200 rpm |
| Trough capacity | 12.5 l | 40 l | 60 l |
| Total capacity with hopper | 30 / 40 / 65 l | 100 / 200 / 300 l | 400 / 600 / 1200 / 1800 / 2400 l |
Feeding element selection
Spiral or auger screw?
The right feeding element has a direct bearing on how stable and repeatable the feed is. Depending on the properties of the bulk material we therefore use two types of screw, which can be swapped freely to extend the feeding range.
Not sure which element to choose? We run feeding trials on the customer’s actual material — the choice of screw or spiral is confirmed by measurement, not by catalogue figures alone.
Arrange a material trialVolumetric vs gravimetric
When to choose a volumetric feeder?
A volumetric feeder is the optimum solution in applications where the material has a reasonably constant bulk density and accuracy requirements are less stringent than for multi-ingredient recipes. It is also the usual choice for feeding material into a weigh hopper, a mixer or a pneumatic conveying system.
Where accuracy better than ±0.5%, full traceability of the mass flow or process validation (GMP) is required, we recommend the gravimetric DSL G instead. It is worth stressing, though, that any DSL V feeder can be upgraded to the gravimetric version at any point.
| Criterion | Volumetric DSL V | Gravimetric DSL G |
|---|---|---|
| Measurement principle | Constant volume per unit of time | Continuous loss-in-weight measurement (LIW) |
| Typical accuracy | ±2–4% of set value after calibration | <±0.5% of set value |
| Feedback loop | None (open loop) | PID controller (closed loop) |
| Density variation compensation | ✗ Requires manual recalibration | ✓ Automatic, in real time |
| Capital cost | ✓ Lower — simpler design | Higher (weighing system + controller) |
| Upgrade path | ✓ Can be upgraded to gravimetric | Complete system from the outset |
| Optimal application | Homogeneous materials, feeding into vessels, conveying | Multi-ingredient recipes, costly raw materials, audits |
Operating principle
Operating principle and typical applications
In a volumetric feeder the bulk material passes from the hopper into the trough, where the feeding element — a screw or a spiral — moves it along at a controlled rotational speed. Volumetric feed rate depends directly on that speed and on the geometry and diameter of the feeding element. The horizontal agitator, driven by its own motor, keeps the screw evenly filled, which matters particularly with cohesive and difficult-flowing materials.
DSL V feeders are used in a wide range of process configurations — feeding material into a weigh hopper or mixer, forming part of a pneumatic conveying system (supplying rotary valves), metering on a packaging filling line, feeding raw material beneath a Big-Bag emptying station, and running as a standalone feeding unit in simpler continuous applications.
Options and configuration
A feeder configured around the material and the process
Every DSL V screw feeder is assembled from modules chosen to suit the properties of the bulk material and the role of the unit in the installation — from hopper capacity, through trough geometry, to hygienic or explosion-protected builds.
Extension hoppers, 30–2400 l
Every trough can take hoppers of various capacities, including geometries that ease material flow, or a circular cross-section with an additional vertical agitator for difficult-flowing and sticky materials.
Interchangeable feeding elements
Screws and spirals of different diameters and pitches can be swapped freely within a single unit — a quick way to change the feed rate range when the product changes, and easy to strip down for cleaning between batches.
Batch feeding
A shut-off valve on the material stream allows batch operation: coarse feeding at full speed and precise feeding at reduced speed, with the cut-off point corrected on the basis of previous weighing results.
Hygienic build
Continuous welds inside and outside the structure, with internal surfaces and welds ground smooth (Ra<0.8 µm) — for the food, pharmaceutical and cosmetics industries.
Drive system
A 3×400 V motor with an SEW worm gearbox; optionally a 3×500 V drive, an aseptic version, or a frequency inverter integrated with the feeding element gearbox.
ATEX build and other options
An Ex version for potentially explosive atmospheres, a vertical outlet pipe, and an upgrade to a gravimetric loss-in-weight system — without replacing the feeder itself.
Industries and applications
Applications across key industries
FAQ
Frequently asked questions
Why InterProcess
Why choose our solutions?
In-house manufacturing
We design and build DSL V feeders at our own works.
A clear upgrade path
Every DSL V can be upgraded to the gravimetric DSL G version.
End-to-end delivery
From design through to commissioning and service.
Experience across many industries
Food, chemical, pharmaceutical and construction.
Safety and hygiene
Systems compliant with ATEX, HACCP and GMP.
Technical support and service
With a fast response, including 24/7 cover.