Core technology
Piston-whistle horn
Also known as piston whistle horn, rotary-disc horn, whistle horn.
A piston-whistle horn is a sonic horn whose sound is generated by a reciprocating piston or rotating slotted disc inside the driver, rather than by a flexing diaphragm. The mechanism is closer to a steam-whistle or ship's siren scaled to industrial duty, and tends to occupy the upper end of the audible cleaning band — 250 to 450 Hz.
Where piston-whistle horns are preferred
Higher frequencies carry more acoustic energy per unit volume and couple efficiently into compact internal geometries. That makes piston-whistle and related high-frequency designs the usual choice for:
- Fabric-filter compartments where filter bag spacing is tight
- Catalyst layers in SCR reactors where ash needs to be lifted from cell faces rather than projected across a large open volume
- Small hoppers and cyclones where wavelength matching benefits from shorter waves
In larger open vessels — ESP fields, preheater cyclones, recovery-boiler superheaters — long-wavelength low-frequency diaphragm horns penetrate further and are usually preferred.
Trade-offs versus diaphragm horns
| Attribute | Piston-whistle horn | Diaphragm horn |
|---|---|---|
| Typical frequency band | 250–450 Hz | 60–250 Hz |
| Penetration in large vessels | Limited | Excellent |
| Energy density at the target | High at short range | Moderate over longer range |
| Wear part | Piston, seals, slot disc | Single diaphragm |
| Best suited to | Fine dust, dense catalyst, small geometries | Open vessels, bulk solids |
Related terms
Related terms
- Sonic hornA sonic horn is a pneumatically-driven low-frequency sound emitter (typically 60–400 Hz at 140–180 dB SPL) used to dislodge particulate fouling from boilers, ESPs, baghouses and process vessels.
- Diaphragm hornA diaphragm horn is a sonic horn whose sound is generated by a vibrating titanium or stainless-steel diaphragm driven by pulsed compressed air. The dominant form-factor for low-frequency industrial cleaning.
- Bell hornA bell horn is the conical or exponential flare that amplifies and projects sound from an industrial sonic horn's driver into the vessel being cleaned.
- High-frequency acoustic cleanerHigh-frequency acoustic cleaners operate at 250–450 Hz. The shorter wavelength carries more energy per unit volume and suits fabric filters, SCR catalysts and small hopper geometries.