Pipes
(A) Noise Problems
Air-borne Noise
• Water flows in a pipe causing vibration at the pipe wall and generating broadband noise which may cause noise disturbance to nearby residents (see Figure 20). When the water flow changes direction suddenly because of obstacles in the pipe such as sharp bends or valves, a loud noise is generated which becomes louder with increasing water flow rate and pipe size.
Structure-borne Noise
• Vibration from the water flow in pipes may be transmitted from the pipe runs to the interior of the building through building structure where the pipes are mounted. It becomes more severe when the pipes are in direct contact with large planes such as walls or slabs (see Figure 21). The vibration transmitted may activate the building structure to generate noise which causes noise disturbance to residents inside the building.
(B) Practical Remedies
Air-borne Noise
• Use pipes with larger radius bends (see Figure 22) so as to minimize vibration of pipe walls.
• Use rigid mountings around the bend with suitable vibration isolators (see Figure 22) to minimize pipe vibration.
• Apply pipe lagging to damp the pipe ringing noise (see Figure 22).
• Use a larger pipe or adjust water flow velocities to below 2m/sec to minimize pipe vibration.
(Noise Reduction Up to 10 dB(A))
Structure-borne Noise
• Use vibration isolators for attaching pipes to walls, ceilings or floors (see Figure 23), thereby isolating them from the building structure.
• Isolate pipes where they penetrate the slabs and walls by compressible materials, such as rubber sleeve or glass fibre packing (see Figure 23), thereby isolating them from the building structure.
• Install pressure reducing valves (see Figure 24) to regulate water pressure and hence the water flow, thereby reducing vibration of pipes.
(Noise Reduction Up to 20 dB(A))
