What is the difference between sound power and sound pressure level?

Sound power level is an intrinsic characteristic of the source while sound pressure level is the value usually measured and it depends on the sound power level distribution over the measurement surface.


Can sound power level be measured?

We usually measure the sound pressure level, which is also what we hear. Sound power level can be then calculated from this value.


What is the difference between absorptive and reactive silencers?

Absorptive silencer: sound generating vibrational energy is dissipated into heat as a consequence of frictional forces due to interaction between flow and porous media. Particularly efficient at high frequencies.
Reactive silencer: evolving through different sections and volumes the fluid changes its acoustical properties, thus inducing partial reflection of the incident acoustic wave and reducing transmitted noise. Ideal for low frequencies, though not very effective at high frequencies.


Are you ISO 9001/2008 certified?

Yes, you can see/download our certificate here.


How long has Stopson been designing silencers?

Stopson Italiana has been engineering and manufacturing silencers and other soundproofing products for 50 years.


Where are Stopson soundproofing installations worldwide?

Stopson Italiana can count on a global customers base throughout the world. Here you can see a map of our main projects/installations.


Have you ever tested your silencers in actual operation?

Yes, our products have been tested several times directly or by third parties.


What is the largest flow rate that Stopson silencers can bear?

Stopson’ solutions are tailor-made according to customers’ prescriptions. However, i.e. for steam silencers, silencer with 700 t/h flow rate has been sized.


Can Stopson supply ASME Code design report, welders and welding procedures for pressure parts?

Stopson designs pressure parts of silencers, e.g. diffusers only, as per ASME Codes and can supply calculation reports, welders qualifications and welding procedures.


Are Stopson’ silencers certified according to PED and CE-marking?

Yes, the diffusers of our silencers can be PED certified and CE marked if they fall under the applicable category.


What information is required for Stopson to size and quote a silencer?

Fluid type or its composition, flow rate, pressure and temperature upstream the valve, piping specification upstream silencer, e.g. size, thickness, flange rating, max allowable pressure drop and acoustic requirements, e.g. required sound pressure level and measurement point position referred to the silencer’s position or attenuation.


Can you provide paintings according to contractor specifications?

Yes, Stopson Italiana can provide highly engineered solutions according to customer’s requirements also for surface treatment.


What Kind of fluid can be vented through our silencers?

Our silencers are mainly designed for superheated steam, saturated steam (vapor quality over 92-93%), air and nitrogen. In addition to these common applications, we can treat any kind of gaseous mixing. A special application is related to oxygen venting, for which we can design silencers according to high safety standards required.


What is the influence of noise coming from piping and valve?

Since valve is generally the noise source, valve and piping upstream silencers are noise sources which can strongly limit measurable silencers performance. Stopson can provide advice for reducing these noise issues and allow our customers to fulfill the overall acoustic requirements.