Wrapping a silencer or blower exchanger

[Shane T]

I know Kevin Brenny mentioned that wrapped his silencer some sort of foam. What was it? Any other suggestions? I have opened up the plumbing on the exhaust side of the blower so I anticipate loss of heat and want to salvage what heat is left. The shell is made of thin gage metal. I'm also thinking it may help to quiet the unit.

 

[KBRENNY]

I used a closed cell foam which is normally used for anti fatigue mats, it is sol many places but I think I got mine a sam's club. I wrapped the 4" stoddard silencer and the 4" flowmaster with it and when I removed the flowmaster the foam had melted and shriveled up like a shrinky dink. I dont understand because the flowmaster was after the stoddard and the foam on the stoddard still looks new.

 

[gasaxe]

not sure what the internals are on a stoddard but i would guess there is some sort of packing around the core that keeps the outer shell cooler compared to a flowmaster which is a chambered muffler with no packing.

 

[Greenie]

My guess is a "muffler" will never compare to an industrial "silencer" for it's intended task, and I agree the outside temp had to do with insulating material which is probably linked to why the silencer works better than the muffler.

 

[Duane Oxley]

Not necessarily...

A muffler will have to be larger to accomplish the same task, but can be large enough to be quieter, actually.

I think that the advantage of silencers comes from the fact that they can be very compact, relative to mufflers.

Mufflers cost less... unless they're stainless steel, of course.

In my experience, the higher the RPM of the blower, the better the silencers sound, vs. standard mufflers. Silencer manufacturers are keenly aware of how well their silencers do in regard to blower RPM in particular, which is why you'll hear them mention "transition speed" as a critical factor, when spec'ing one in. (Each model of blower has it's own transition speed, but generally, it's above 3,200 RPM...)

 

[Greenie]

I think one of the biggest differences id muffler builders look for a "tone" as well as some silencing, Industrial silencers just look for "quiet". There is also a difference in real CFM passing through one vs: the other, one was designed to move airflow, the other exhaust gasses.

I know some high perf. mufflers make lofty claims like 800 cfm, but ain't no way in hell that is gonna happen through a 3" pipe unrestricted.

 

[Duane Oxley]

"...claims like 800 cfm, but ain't no way in hell that is gonna happen through a 3" pipe unrestricted."

At enough pressure, it will... At enough pressure, restriction becomes less of an issue. The more pressure behind the airflow, the more resistance airflow can encounter and still make it through.

The thing is that a car or truck motor can handle back pressure much better than a 2 cyl. air- cooled, etc. I don't know what it is for a 6 or 8 cyl., but for an air- cooled, it's about 3 PSI.

The vast majority of blowers used in our industry generate no more than 10 PSI... some, as little as 7 PSI, if the spec's aren't exceeded via over- driving, etc.

Taking the motor out of the equation (i.e., not combining it with blower exhaust and then sending them through the same silencer simplifies things a lot in that regard...

It's the same as pump pressure, in principle.