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Advanced Noise Study
for Blowdown Systems


with our partner KÖTTER CONSULTING ENGINEERS we offer our customers a look at the full picture.

Noise levels of blowdown systems regularly exceed allowable limits. The underlying causes are manifold and include issues such as unexpectedly high mass flow rates, noise emission from sonic flow within piping, the use of ineffective silencers or excessive noise radiation from thin-walled piping.


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At the centre of our noise study is an accurate acoustic model of the blowdown system that includes all of its noise sources. After careful plausibility checks of the process conditions, the noise power spectra of all sources are calculated and the noise levels at the receiver location predicted. Based upon these results the technical specifications for silencers or acoustic lagging of piping systems are developed.

Based on our vast experience in the oil, gas and power industry, a noise study fully eliminates the risk of excessive noise emissions from blowdown systems and cost overruns due to unexpected noise mitigation measures.

The advanced noise study can be ordered independently of our silencers that enables an optimized acoustic design of the entire blowdown system. Especially with complex systems, the advanced noise study can avoid additional costs.

Scope of Work

 1. Data Review and Plausibility Checks



Review of valve / orifice datasheets

Definition of allowable noise level at the receptor location

Definition of basic information for silencer design

Plausibility check of process conditions within the blowdown system
(mass flow, pressure difference, temperature, MACH number)

Identification of sonic flow regions and secondary noise sources

 2. Calculation of Noise Power Spectra



Calculation of sound power level of primary noise source (valve or orifice) according applicable standard for simplified estimations (e.g. according VDMA or API)

Extended calculation of noise power spectrum of primary noise source (valve or orifice) and secondary sources (flow with high MACH number, unimpeded outflow at the blowdown opening)

Extended calculation of noise power spectra for all piping surfaces and the blowdown opening

3. Noise Propagation Calculation and Noise Reduction Measures



Calculation of the required insertion loss of the silencer under free field conditions considering a simplified estimation of the primary noise source

Calculation of noise level at the receptor location using an acoustic model

Optimization of the required insertion loss of the silencer and the allowable discharge velocity

Definition of the required acoustic pipe lagging and other measures

Documentation of the study in a factual technical report

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