Dry, self-cleaning filters for steady airflow

Introduction

In a high-performance road sweeper, air doesn’t just carry debris, it carries fine dust, moisture, and other contaminants. Sweepers do employ some form of pre-separation to handle the heavy, visible debris early in the airflow path. After coarse debris is removed through pre-filtration systems, there are two persistent challenges in the airstream: Fine dust and moisture. In addition, there’s a third challenge: ensuring that the filters themselves stay clean and functional throughout the shift.  At this stage of the airflow system, it must effectively do three things well: trap fine particles, remove excess moisture, and keep its filters from getting choked..

Achieving all of this, however, is easier said than done. Fine dust tends to bypass basic separation systems and embeds deep into filter cartridges. Moisture in the airstream, especially in monsoon or tropical zones, can quickly turn that dust into sticky paste and cause filter caking. This causes a slow, invisible buildup that blocks airflow and forces the engine and blower to work harder, long before the operator notices visible issues.

Read more

Flawed filtration: what sweepers do wrong or don't do at all

In most machines, fine dust is left to the final filter stage. after basic pre-separation, dust-laden air is sent directly to a cartridge or cloth filter. the filters have to stop extremely small, and often sticky particles without any support. without upstream polishing stages (mentioned in cycloshieldTMM), humidity control, or proper filter cleaning, filters in standard sweepers often become overloaded early in the shift.

Read more

What most sweepers do- and why it falls short

Most sweepers use flat-panel filters, non-pleated socks, or basic
bag filters made from cellulose or synthetic cloth. These formats are widely used because they’re cost-effective, simple
to install, and easy to replace. For manufacturers aiming to hit a functional price point, these filters offer just enough performance to capture visible dust under dry, controlled conditions.

Challenges:

However, these filters have very limited surface area, which means they clog quickly, especially when exposed to fine dust. The smaller media footprint offers less space for dust to settle, so even a moderate load clogs the filter fast. These filters also tend to hold dust rather than shed it, especially once moisture is present. As a result, airflow drops early in the shift, performance fades, and filters need frequent servicing or replacement, raising downtime and operating costs.

In most machines, the filter compartment is placed in a rear-side, roof-mounted, or insulated interior location, far away from engine heat. This placement simplifies the body layout and keeps filters out of high-vibration or high-heat zones. It’s a decision often driven by packaging convenience, not filtration performance.

Challenges:

But this distance from heat creates a major issue in wet or humid conditions. Cold compartments act like condensation traps. When warm, humid air hits these surfaces, moisture forms instantly, turning fine dust into sticky paste. Even high-grade media struggles when it’s wet. This encourages filter caking, drastically shortening usable filter life and accelerating suction loss.

Most standard sweepers require frequent manual filter cleaning to compensate for dust loading, moisture caking, and lack of automatic recovery. This typically happens at the end of each shift, or worse, mid-shift, using compressed air (manually) blow-out through access hatches. Filters must be removed or serviced manually, often in cramped, hard-to-reach compartments. In humid or dust-heavy zones, this cleaning is required daily just to keep airflow from collapsing.

Challenges:

This maintenance is time-consuming, labor-intensive, and easily skipped under field pressure. When it is skipped, filters clog mid-shift, suction weakens, fuel use climbs, and cleaning quality suffers. Operators often continue working with underperforming systems, unaware that the machine is far below spec. The result is a cycle of poor performance, rising maintenance effort, and escalating total cost of ownership.

How to cleanTM solves each failure point

Stratus road sweeper uses rear-mounted pleated cartridge filters, not flat panels or bags. The rear-mounted pleated cartridge filters receive air that has already passed through upstream separation stages like an inertial separator and cyclone (Read more: CycloShield). Pleating greatly increases the filter’s surface area, allowing it to capture fine particles without clogging early in the shift.

Benefits:

More surface area means dust is distributed over a wider space, preventing overload. Filters last longer, airflow stays steady, and performance is more consistent—especially in dust-heavy conditions.

Stratus sweepers mount these pleated cartridges beside the engine cowling, where radiant heat raises the bay’s ambient temperature. Incoming air that may carry up to 90% RH (relative humidity), especially in the rainy seasons or tropical areas, is conditioned down to 45–55% RH before touching the filter.

Benefits:

By lowering the relative humidity before filtration, Stratus road sweeper prevents condensation from forming on the filter, keeping the media warm, dry, and resistant to caking. This ensures consistent performance even in muggy monsoon conditions ot tropical climates.

Instead of relying on end-of-shift manual cleaning only, Pulse Clean fires a reverse pulse every 60 seconds from a 6-bar air reservoir. Dust is dislodged before it embeds into the media, preventing premature clogging during operation.

Benefits:

This keeps the filter clean continuously during operation, eliminating the need for mid-shift cleaning or intervention. Maintenance effort is reduced in frequency and intensity, significantly compared to traditional systems, uptime increases, and airflow stays within ±5% of its starting volume all shift long.

Most sweeper filtration systems are built to do the bare minimum, and it shows in the field. They clog early, struggle in humidity, and demand constant intervention to stay operational. Pulse Clean turns that reactive cycle into a proactive system. By combining pre-cleaned airflow, humidity conditioning, and automatic filter maintenance, it tackles the three most critical failure points in conventional sweeper design. Resulting in longer filter life, fewer service stops, and reliable suction hour after hour. Even in the toughest conditions, it performs consistently across all seasons and environments.