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Pneumatic Mufflers Explained – Compressed Air Silencers Guide

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Pneumatic mufflers, or otherwise known, silencers, quietly and safely vent pressurized air into atmosphere on an air compressor. This article will provide you with all the relevant information about them for you to gain a better understanding.

Table of Contents

What Are Pneumatic Mufflers?

Without pneumatic mufflers, air exhausting from many types of pneumatic-powered equipment can be extremely loud and detrimental to the surrounding environment, possibly even harming workers.

Noise results when fast-moving, turbulent exits a port and collides with the surrounding static atmospheric air. In most industrial settings, airflow exits at a constant velocity through an orifice and generates fair amounts of noise, related to the choking effect of the port and its velocity.

Acoustic power, another term for “noise”, is a product of factors like air density, turbulence and most certainly, velocity. This has an exponential effect on noise generation, and with pressures above 25 PSI, reducing pressure has little effect on noise abatement.

This is why mufflers are needed and so are commonly installed on air valves, cylinders, manifolds and fittings on compressed air systems.

They are most typically installed directly at the exhaust port to diffuse the released air through a porous material that increases the surface area which, in turn, reduces the velocity, turbulence and noise levels.

Noise in compressed air systems or equipment can be reduced by 15 to 35 decibels by using a pneumatic muffler which is fairly significant!

Pneumatic Muffler Materials

Pneumatic exhaust mufflers can be constructed of plastic or metals like brass and stainless steel. They come in a variety of versions depending on the application, with most design styles being cone, flat-face or cylindrical shapes.

Plastic units tend to have injection molded bodies with plastic fibers, sintered plastic or metal powder inside acting as a noise reducing medium. These designs are economical, lightweight and offer very high chemical resistance, and better noise reduction than the metal versions.

Brass mufflers often have machined metal bodies with sintered bronze powder or compacted metal wool as the silencing material, allowing them to handle temperatures up to about 300°F.

The stainless steel silencers have a metal base with sintered stainless powder, wires or a woven mesh. These designs can reach working temperatures of up to 400°F, but are the most expensive of the mufflers. They’re great for applications that require corrosion resistance, durability and operation in washed down or sterile environments.

Pneumatic Mufflers Explained
ADwarf, CC BY-SA 3.0, via Wikimedia Commons

Pneumatic Muffler Sizes

Pneumatic muffler sizes range from less than 0.125″ to above 2 “. When selecting your size, they should meet the manufacturers specification for allowable pressure range, connector size and type.

Important Considerations

The most important consideration when installing pneumatic silencers is the effect the unit will have on airflow in the compressed air system. If there is any significant restriction then the working capacity of the air compressor will reduce, due to back pressure which will be caused by under sizing or contaminant clogging.

Therefore, appropriate selection is very important and maintenance essential. A unit with extra flow capacity should be opted for if an application is particularly sensitive to back pressure.

The cleanliness of the compressed air is also important in affecting back pressure and noise reduction. Thus, proper filtration is a necessity.

It’s important to be aware that the porosity and surface area of the diffusing material vary among different products. Small pore sizes provide compact and effective silencers with reasonable air-flow rates.

However, in contaminated air lines, mufflers can quickly become restricted and interfere with the working capacity of the compressor to which they’re fitted and therefore, may demand larger-pore materials.

Silencers may also be able to combine several functions in a single assembly for simplicity and space savings which can be very handy. This would allow you to have a muffler with adjustable throttle valves to control the flow rate as air exits the device, and a filter to remove oil mist and dust in the exhaust air before it reachers the surroundings.

Pneumatic mufflers are more often than not, connected to ports using a threaded male end. Manufacturers supply products that are compatible with most common thread standards. It may be possible to find some push-to-connect devices.

Silencers should be mounted so that contaminants do not block the silencer or exhaust port. E.g. horizontal or inverted mounting lets contaminants drain through the muffler using gravity and prevents clogging.

Tip: mount mufflers in protected areas to avoid accidental damage. Plastic-bodied mufflers that protrude from the machine surface are particularly prone to impact and breakage.

Pneumatic Mufflers Readily Available on Amazon

I have picked out some examples of pneumatic mufflers that are readily available on Amazon for purchase. The first is this Beduan plastic compressed exhaust silencer that boasts a maximum operating pressure of 150 PSI.

Next up we have the uxcell brass body pneumatic air muffler with a sintered bronze filter element, possible of working with pressures up to 300 PSI.

Last up, this MettleAir zinc plated stainless steel silencer.

FAQs (Frequently Asked Questions)

What is a pneumatic muffler?

A pneumatic muffler is a device that safely and quietly vents pressurized air into atmosphere so that the noise from the pneumatic equipment is reduced.

What is the function of exhaust muffler?

The function of an exhaust muffler is to diffuse the released air through a porous material that increases the surface area of the air, allowing a reduction in velocity, turbulence and most importantly, noise level.

What is muffler in hydraulics?

A muffler in hydraulics is designed to attenuate and absorb hydraulic pulsation, in order to reduce the overall noise levels of a hydraulic system.

If you have any questions regarding pneumatic mufflers, please leave a comment below, with a photo if applicable, so that someone can help you!

By Aidan Weeks

A passionate Mechanical Engineer with endless enthusiasm for fluid power - building off the back of over 18 years of high quality contribution and discussion stimulated by Bill Wade here at About Air Compressors. With both practical and theoretical experience in pneumatics and hydraulics, I'm putting my knowledge to work - and working my grey-matter through my research, assistance and publishing work here at About Air Compressors. Feel free to reach out any time! P.S. A HUGE shout out to Doug who really offers such great value to all visitors to About Air Compressors - once again, feeling like I'm standing on the shoulders of GIANTS by getting to work alongside such a great community

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