Bauer Junior vs. compressor theory

[Curious_George]

Background is I’ve been pumping my own air for while with a Coltri. It is so loud all my neighborhood gives me the stink eye even in the middle of the day, so I’m on the hunt for something else. I’ve been looking and studying and have a question for the experts. As I understand it, we want to keep the filter under pressure all the time as much as possible so the desiccant doesn’t get ruined. I see how that’s done in the pic below with the PMV and NRV. All that makes sense. Follow my question below about how this works with the Bauer Junior . . .

While looking at the Bauer Junior flow diagram below, there appears only to be a PMV. What holds the pressure on the other side of the final filter/separator combo? Is it the third stage intake valve? That seems problematic because the seal isn’t perfect with the cylinder/sleeve and the valve itself isn’t likely a perfect seal. Thanks in advance for the education.

 

[tbone1004]

PMV functions as a non-return valve.

What makes you think that a bauer is going to be quieter? Have you looked at what makes your coltri loud and looked at trying to quiet it down? Running a remote intake to something like a Solberg Silencer and you'll be shocked at how much quieter it gets... After that, if it's electric you can replace the fan with an electric fan which will quiet the fan noise, if it's gas you can put a better exhaust muffler and intake filter on there etc.

 

[Curious_George]

Thanks @tbone1004 for your reply.

I think I didn’t ask the original question very well. Both diagrams have a PMV on the fill hose side of the filter. I understand that is all I needed to hold pressure at a minimum psi (2100 or whatever) while the pump is running. My question is about while it’s not running. The example diagram has a NRV on the input side of the filter but the Bauer doesn’t. So I’m wondering does the Bauer not intend to hold pressure when not running?

Regarding the noise question, the air inlet is loud on the Coltri and I can certainly put a quieter filter there. I’m assuming roughly the equivalent noise level vs. the Bauer on the intake so I’m setting that aside from a noise comparison.

Nuvair reports my Mch6 gas model as 86db. They say electric would be 80db but I don’t want to invest money to swap for electric or the hassle of selling the Honda gas motor. Rather just sell as is. I have a line on a Bauer junior block that was robbed of its gas motor already, and am thinking if I built it electric and slowed it down to about 1800 rpm, it would be quieter than the Coltri. I wonder if there will be any noticeable noise difference between an electric motor at 3400 vs 1750? That might further quiet it down.

 

[tbone1004]

the third stage has a non return valve so it can't bleed out through the third stage. If the filter assembly is intended to be semi permanently mated to the pump then it doesn't need a check valve.

You can't slow these pumps down that much since they are splash lubricated, only to about 80% of their rated RPM which doesn't do much for the noise. An intake silencer is going to do the most amount of good for you

 

[tmassey]

I have to echo @tbone1004 here. Muffling the intake makes a huge difference. My compressor is installed in a workshop, with probably 20 feet of 2 inch PVC attached to the intake to get it out of the workshop. I was shocked how much of the sound clearly came from the intake, not just from the compressor itself. I put a muffler on the end of the intake, and it noticeably lowered the overall volume, as well as making what sound remained less noticeable and irritating.

The same is true of the gas engine. Mine is electric, so I have no experience with muffling the compressor. But I have muffled a generator: I used a length of metal exhaust pipe hose-clamped to the on-engine “muffler” and a generic aftermarket metal muffler. It too made a noticeable difference.

YMMV, of course, but worth investigating. Having said that, a quick Google shows a lawnmower as ~90 decibels. I’ve never heard a compressor that doesn’t sound at least mostly the level of a lawnmower, and as a gas compressor, it *is* a lawnmower — engine, anyway. Unless your compressor is way above spec for Sound Pressure Level, I don’t think *any* compressor (even electric) is going to be *dramatically* quieter. It’s probably a lot more effective to manage the sound you’ve got than to hope a different compressor will be dramatically quieter...

Now, if you’re looking for an excuse for a new compressor, by all means. I just think you’ll still have exactly the same noise issues either way.

 

[Couv]

How about a picture of an "intake silencer?" @tbone1004 @tmassey

 

[Wookie]

+3 on the intake silencer.

This is the one from Nuvair....

 

[Wookie]

Muffling the intake makes a huge difference. My compressor is installed in a workshop, with probably 20 feet of 2 inch PVC attached to the intake to get it out of the workshop. I was shocked how much of the sound clearly came from the intake, not just from the compressor itself. I put a muffler on the end of the intake, and it noticeably lowered the overall volume, as well as making what sound remained less noticeable and irritating.

There are a number of steps you can take to muffle the intake noise, and I have to agree with tbone and tmassey that that's your problem. First off, for every 10 feet of length of your suction hose (if provided), you must increase the diameter of the hose by 1/2", so if you put a 20 foot snorkel on a 1" suction, you need the snorkel to be 2" pipe. That doesn't mean that the muffler on the end is 2", just the pipe itself. On the Spree, we had the Air Compressors take suction from the main deck. It was a rare case that we pumped air, and nitrox has it's own problems, but you could stand next to the intake (it was next to the camera table) and have a conversation no issues. Second, we used 2 intake mufflers, the installed on the machine and the second one on the main deck. So by the time the noise made it through the 2 mufflers, it was pretty quiet. NOTE: If you go the 2 muffler route, you must increase muffler size by 1/2 inch as you do the intake size.

 

[tbone1004]

How about a picture of an "intake silencer?" @tbone1004 @tmassey

https://www.amazon.com/Solberg-FS-1...ywords=silencer+solberg&qid=1618338771&sr=8-2

They make them in plastic and metal, and in all sorts of different sizes for the bore. They work. Put one on the pump intake, put one on the motor intake, and you'll be floored at how much quieter it is.

 

[tmassey]

Mine is a a completely different type of thing: a one-off prototype from a client of mine who specializes in wide-band resonators. They are patented and specifically designed for specific applications, so not a generic or available solution. You can kind of think of it like a plastic muffler. For those who are currently bored, more details:

http://www.wocogroup.com/fileadmin/media/pdf/produktflyer/193331_produktfly_breitb.pdf

It just looks like a 5” or so diameter piece of pipe, 10” or so long. Inside it has an inner pipe about 2” in diameter (the diameter of the rest of my piping, so zero restriction) perforated with a certain number of specially-sized holes drilled into specially-sized partitions between the inner and outer pipes. The pdf has a cutaway view of one: the assembled part just looks like a section of larger-diameter pipe.

Think of the holes and chambers like a huge collection of glass bottles the flowing air is blowing over, but instead of making horn sounds, they’re tuned to cancel *out* sounds. It works like magic: minimal restriction, maximum sound cancelling.

Mine wasn’t specially designed for me — it was just an old hand-built prototype laying around. But it works plenty well.

But just because you can’t get a magic wideband resonator doesn’t mean a conventional intake muffler won’t work every bit as well.....

ETA: I forgot about the *engine* intake. That’s almost as noisy as the exhaust! If you have a Chrysler, there’s a decent chance the intake system was designed and built by my client — and it includes some of that wideband resonator technology! As @tbone1004 mentioned, a muffler will help there as well. And as @Wookie mentioned, make sure you size it correctly.