Oblan pre-cleaners
Bullnose Series Pre-Cleaners
Pre-cleaners with a grid screen on top, for trucks, buses, industrial and agricultural machines, earthmoving and mining equipment, pumps and generator sets. They can go inside or outside the machine.

- 6 sizesMO 404 to GR 505
- 3.5 – 40 m³/minairflow
- 60 – 550 hpengine size
- up to 90%dirt removed
The range
Bullnose Sizes
| Model | Airflow, m³/min (CFM) | Engine, hp (kW) | Weight, kg |
|---|---|---|---|
| MO 404 | 3.5 – 7.0 (124 – 247) | 60 – 120 (45 – 90) | 1.70 |
| MO 808 | 7.0 – 11.0 (247 – 388) | 120 – 160 (90 – 120) | 2.25 |
| MO 909 | 11.0 – 15.0 (388 – 530) | 160 – 220 (120 – 165) | 3.30 |
| GR 103 | 15.0 – 22.0 (530 – 776) | 220 – 300 (165 – 225) | 4.15 |
| GR 403 | 22.0 – 30.0 (776 – 1,059) | 300 – 400 (225 – 300) | 5.35 |
| GR 505 | 30.0 – 40.0 (1,059 – 1,411) | 400 – 550 (298 – 410) | 7.50 |
How it works
How the Bullnose Series Works
Inside a Bullnose Pre-Cleaner
Air comes through the grid screen (1), which stops large debris, then through static vanes (2) that spin it. The rotor (5) on two ball bearings (4) ejects the dirt through discharge ports (6), and clean air goes down the outlet pipe (7) to the air filter.
Outside the machine, mount it horizontally so rain can’t get in.

Why the Bullnose series
Compact and Versatile
Inside or Out
Fits inside the engine bay or outside – horizontal mounting outdoors keeps the rain out.
Lighter
Lighter than the MO / GR equivalents for the same airflow.
Filters Last Longer
Up to 90% of impurities removed; filter life up to ten times longer.
Nothing to Power
Self-powered and self-cleaning.
How to choose
Choosing a Model
Size It by Airflow
For turbocharged or turbo-aftercooled engines, choose by the engine’s maximum airflow (m³/min or CFM). The horsepower range is only a guide for naturally aspirated engines.
Match the Outlet
Each model has standard outlet sizes; reducing sleeves adapt it to smaller tubes, from 7" down to 2.5" in ¼" or ½" steps.
Keep It Clear
Pre-cleaners need almost no maintenance – just check now and then that nothing is blocking the intake or the discharge ports.
Ask Us
Send us the engine make, model and power and we’ll pick the model and fittings.
Literature & related
More Information
- Bullnose series data sheet
Sizes, dimensions and outlets · PDF, 702 KB - Sizing chart
Choosing a pre-cleaner by engine · PDF, 92 KB
Not Sure Which One You Need?
Tell us about the job – the machine, the conditions and what it has to do – and we’ll help you choose the right Oblan product.