Complete silencer sets for a blower manufacturer's machine packages

The challenge

A blower manufacturer in the Netherlands builds complete machine packages, and every package needs silencing at each point where air enters or leaves the machine. The intake has to be quiet from the filter outlet onward, the blow-off has to be silenced when the machine vents, and the outlet noise has to be dealt with inside the compact footprint of the machine’s base frame.

One position is harder than the rest. The silencer on the compressor discharge sits in the pressurised air stream, so it is pressure equipment, designed for 4.2 bar(g) and from -10 °C to +250 °C. The manufacturer needed all of these silencers from one supplier, as a set per machine, in its own colours and delivered to its works.

Our approach & engineering

Axces supplied the full silencer set for the machine package and issued its own datasheet for every position. All the silencers are absorption silencers for air, sized to the connections and space of the machine.

One set, every position

• Pre-inlet silencer at the filter outlet, Ø450 mm
• Inlet silencers of Ø600 to Ø636 mm, one version with vent nozzles
• Blow-off silencer with elbow, Ø700 × 2,400 mm, in white
• Outlet silencer built into the machine base frame, Ø500 × 2,420 mm
• Discharge silencer for the compressor stage, Ø508 × 1,570 mm

The discharge silencer as pressure equipment

The discharge silencer was designed to EN 13445 and falls under the Pressure Equipment Directive as Category III. It is specified with 10% radiographic or ultrasonic examination of its welds and a hydrostatic test, with welding to qualified procedures. The other positions are atmospheric, designed for 150 °C.

Construction and finish

The shells are P235GH with P250GH flanges. Inside, a galvanised perforated liner holds mineral wool behind glass cloth and stainless steel gauze, which keeps the fibres in place in the air stream. Every silencer was blasted to Sa 2½, zinc-primed and finished with a polyurethane top coat in the manufacturer’s blue, with the blow-off silencer in white.

• A complete silencer set per machine package, from one supplier
• Pressure-rated discharge silencer to EN 13445, PED Category III
• Outlet silencer integrated into the machine base frame
• Absorption fill held behind glass cloth and stainless gauze
• Coated in the customer’s colours and wrapped for transport

Scope of supply

• 22 × blower silencers across all positions of the machine package
• PED Category III discharge silencers with weld examination and hydrostatic test
• General arrangement drawings, part lists and a visual and dimensional report for each silencer
• NDE and welding plan where applicable, and installation, operation and maintenance manuals
• Delivery to the manufacturer’s works in the Netherlands

Results

The first silencer set was delivered in spring 2025 and the rest of the order by the end of September. The manufacturer then placed a repeat order for another six-piece set, delivered in November 2025.

• 22 silencers in three deliveries in 2025
• A repeat order after the first sets were delivered
• Discharge silencers designed as PED Category III pressure equipment

Related reading

• Exhaust silencers explained: absorptive, reactive and combination designs
• Pressure vessel design and certification: PED 2014/68/EU categories and what they require
• Understanding dB(A) reduction targets: how to specify acoustic performance
• Combined pressure and noise control: when one device must do both