Noise control for chillers on the datacentre roof – ultra-light, A1, within the pressure reserve
Free-standing acoustic packs for chillers with 20 or more fans. Built with ABSORA HSA3 technology: metal acoustics instead of mineral wool, Helmholtz tube silencers directly above the fans.
Data centres set different conditions for noise control
Large chiller fields on rooftops run around the clock, and the strictest noise limits apply at night. At the same time, the enclosure must not cost any cooling capacity or overload the roof and gantry.
- Static pressure: manufacturers usually allow only 30–35 Pa of reserve. Every pascal above that costs fan power and PUE.
- Structure: conventional steel splitter enclosures add many tonnes to the roof and gantry.
- Fire safety: combustible insulation on a data-centre roof complicates the fire safety concept.
- Low frequencies: after attenuation, the 63 Hz band usually determines the level. Conventional splitters attenuate little there.
- Schedules: many identical units, fixed delivery cycles, short installation windows per unit.
Three building blocks: noise down, air through
HSA3 metal acoustics
Corrugated, micro-perforated metal sheets with a resonance cavity. Absorbs without mineral wool or foam, weather-resistant, A1 non-combustible.
HSA3 in detail →Helmholtz tubes Ø 200
Tubes with internal resonance chambers, tuned to 63–250 Hz. Rounded leading edge, staggered arrangement: ζ ≈ 0.3 per row at approx. 1.6 kg/m.
Separation plane at the fan deck
Supply air through the long sides, exhaust air through the silencer directly above the fans. The separation plane prevents warm exhaust air from recirculating.
Air flow →
Reference data centre: chillers on the roof
22 axial fans and 380,000 m³/h of air flow per chiller, installed on a rooftop gantry.
Unit without pack with acoustic pack (forecast)
| Octave | without pack | Attenuation | with pack |
|---|---|---|---|
| 63 Hz | 78.6 | −8 | 70.6 |
| 125 Hz | 75.5 | −12 | 63.5 |
| 250 Hz | 80.5 | −16 | 64.5 |
| 500 Hz | 84.8 | −20 | 64.8 |
| 1 kHz | 86.1 | −22 | 64.1 |
| 2 kHz | 85.6 | −23 | 62.6 |
| 4 kHz | 87.3 | −23 | 64.3 |
| 8 kHz | 76.6 | −21 | 55.6 |
| Total | 92.6 | −18.3 | 74.3 |
| Pressure drop per air path at 380,000 m³/h | Δp |
|---|---|
| Supply-air silencer, 3 rows (4.0 m/s in the gap) | 10.6 Pa |
| Deflection in the side aisle | 1.4 Pa |
| Plenum above the fans | 3.3 Pa |
| Exhaust silencer, 3 rows (3.2 m/s in the gap) | 5.6 Pa |
| Total / unit reserve | ≈ 21 / 30 Pa |
Forecast values from a reference design. Every project is designed individually for acoustics and with CFD; performance is verified by an in-situ differential measurement after commissioning.
From enquiry to measurement
Enquiry
Unit data, noise target, pressure reserve
Design
Octave balance, CFD, structural design of the enclosure frame
Manufacturing
ABSORA, Berlin – approx. 12 weeks after approval
Delivery
DAP site, in step with unit installation
Installation
Approx. 5 working days per unit
Verification
In-situ differential measurement
With this information we can reply fastest
- Manufacturer, unit type, quantity
- Dimensions L × W × H
- Number of fans
- Air flow per operating case
- Pressure reserve of the unit (Pa)
- Sound power per octave (data sheet)
- Noise target (LWA or receiver point)
- Layout plan, gantry, clearances
- Delivery date and scope of supply
Frequently asked questions
Does the acoustic pack cost cooling capacity?
No, as long as the pressure drop stays within the reserve the unit manufacturer already allows for (usually 30–35 Pa). We design supply and exhaust so the pack stays below it, and verify this with CFD.
Why Helmholtz tubes instead of splitters?
After attenuation, the low-frequency range around 63 Hz usually determines the level. The resonance chambers of the HSA3 tubes are tuned to exactly that, with low weight and low pressure drop.
Are the packs non-combustible?
Yes. The inner lining and silencers are made of HSA3 metal acoustics (A1), without mineral wool or foam.
Who manufactures and installs?
Design: Silent Engineering. Manufacturing and installation: together with ABSORA GmbH, Berlin. Installation takes approx. 5 working days per unit.
Request a project
Send us the unit type, quantity and location – or get a budget price straight from the configurator.
ForCoTech · Silent-Mode
Via Trento 22 · 23875 Osnago (LC) · Italy
E-Mail: info@forcotech.com