Planning Guide – CR Duct vs Duct Silencer

Overview
Climate Recovery has previously employed the Swedish Statens Provningsanstalt (SP Certification) to perform measurements of the CR Duct sound-absorbing properties. Recently, complimentary measurements were performed with the help of Swegon, a Swedish air-handling manufacturer. All current measurements confirm those previously performed, though to a more definitive degree. All measurements were performed on the 1/3rd octave band level. The lowest sound damping values of all measurements were chosen.

Comparison
The following show the CR Duct of each diameter (Ø) against industry standard duct silencers of both 50mm and 100mm insulation thickness. All measurements are done in decibels (dB) with direct comparisons made between similar frequencies.

Example
Ø160 CR Duct 2,35m – 230mm outer diameter Ø160 SLCU 100mm insulated silencer – 365mm outer diameter All CR Ducts outer diameters are 60-70mm greater than internal diameter.

CR Duct silences 48 dB at 1k Hz while SLCU dampens by 11. (11-46) makes the Difference of -37, noted with a star (*). The Minimum CR Length is what is required to match the silencing of the SLCU device in direct relation to the Difference, in this example 0,5 meters. The red figure is the critical frequency point, meaning the most CR Duct required in this specific comparison. Here, 2,3 meters of Ø160 CR Duct is required to match the silencing of 8k Hz by the Ø160 SLCU 100mm. Finally, the weight of the CR Duct is 2,9 kg lighter than the silencer.