1/4″ NPT exhaust mufflers are perfect for reducing pneumatic noise levels in the work environment. Muffler – filters use a porous sintered bronze, bonded to a copper plated steel pipe threaded fitting. 40 micron filters diffuse air and muffle noise from exhaust ports of air tools, cylinders and valves to an acceptable OSHA noise requirement. Pneumatic exhaust mufflers have a maximum air flow of 20 SCFM at 100 PSI, or an overall maximum operating pressure of 300 PSI.