In residential as well as commercial buildings noise is generated in piping systems. An important consideration for architects and engineers when designing these buildings is the noise levels contributed by sanitary drainage pipes. These considerations influence the materials of pipes used, their orientations, and even the type of false ceiling. As a premier supplier of cast iron pipes and fittings, we at BIC detail in this blog a concise version of the available literature.[i] It entails the process of how noise level tests were conducted and the consequent results obtained for cast iron pipes in comparison with other materials.

Methodology Used

The measurements were carried out in the acoustical laboratory of Peutz bv in Mook in the Netherlands.

The variables of interest examined in this study are as follows:

Material of drainage pipe
Construction orientation

The experiment was carried out at a flow rate of 3.0 l/s.

Materials and constructions

The following table lists the types of pipes used for the experiment.

Drainage Pipe

1. Type: Cast Iron
Mass: 8.5 kg/m
Inside Diameter: 103 mm
Outside Diameter: 110 mm

2. Type: U-PVC
Mass: 1.3 kg/m
Inside Diameter: 103 mm
Outside Diameter: 110 mm

3. Type: Polyethylene (PE)
Mass: 1.23 kg/m
Inside Diameter: 103 mm
Outside Diameter: 110 mm

Standard clamps and rubber inlays were used. The pipes were installed in three variations as shown in the diagram below:

An offset with two 45º bends.
Straight vertical
Straight horizontal

Calculations

To quantify the measured noise levels in the given room, a standard sound pressure level Ln in dB(A) is calculated as follows:

Where:

Ln = sound pressure level (dB)

L0 = measured sound pressure level caused by water flow in the pipe (dB)

A = determined absorption area (m2 area of opening)

A0 = reference absorption area (10 m2 area of opening)

The result obtained is detailed in the following table:

Table: Sound pressure level L_n in dB(A) for three variants and pipe materials, flow 3.0 l/s

It can be seen that the sound pressure level for the offset vertical with two 45° bends is higher than the straight vertical and horizontal pipe. BIC cast iron pipe has the lowest noise production with similar sound pressure levels for the straight vertical pipe and the horizontal pipe.

———————————————————————–

[i] Measurement of the noise production in drainage pipes. W.G. van der Schee. https://www.irbnet.de/daten/iconda/CIB_DC25341.pdf