Compressor noise rating - at 7m??

[Gooner2826]

Afternoon gents,

Milwaukee batteries have given up the ghost and I can’t be bothered to spend hundreds, to replace them. I’m a hobbyist working out of my house garage, where I can get a full suite of aircat tools for all my needs for the same price.

Currently have a SGS belt drive but see that now ‘silent’ compressors are now a thing. Saw this interesting Hyundai one which ticks all the boxes, but see the DB rating is taken at 7m away when you actually scroll down to the spec - is there a golden equation for what this sounds like next to it? Or is it just pure marketing gimmick? As that doesn’t sound like it would actually be that quiet?

https://hyundaipowerequipment.co.uk...349&gbraid=0AAAAAC96wz5HeQ5fEuxA3wJ0IWZmLdaWM

 

[Jackimus]

If I'm remembering right, decibels increase/decrease by 6 for every doubling/halving of distance - so this machine would be 75db at 3.5m, 81db at 1.75m.

 

[keithski122]

I have the 50ltr version and love how quiet it is, with my insulated garage doors closed you can barely hear it outside. Now sure how good it would be with air hungry tools, I mainly use mine for an air stapler and spraying glue in fairly small amounts with a gravity feed gun.
edit:- just seen the one you show has twice the power on the motors.

 

[Erie Fred]

Compressor is not the only noise.

 

[Gooner2826]

I have the 50ltr version and love how quiet it is, with my insulated garage doors closed you can barely hear it outside. Now sure how good it would be with air hungry tools, I mainly use mine for an air stapler and spraying glue in fairly small amounts with a gravity feed gun.
edit:- just seen the one you show has twice the power on the motors.

Had a look at this one, it’s rated at 60db. Would you say that’s about right for it up close?

Just doesn’t feel like it makes sense - 9 DB more for double the power, definitely makes me question it!

 

[tom2207]

sound is strange , 3db is basically double the power , and the inverse is true too ,,, to make something twice as loud takes aprox 10 times the power , a hoover runs about 80db , a fridge is about 40 ...and non of it matters really , its about whats around you , in a quiet house a ticking clock can be heard everywhere , in a shop a 72db radio is background , compressors can be boxed and they dont mind much , but an air die grinder is loud no matter what , and its at a higher frequency and that travels differently than the lower frequency of a compressor .
double glazed windows and insulated walls will help , but so will a bit of consideration ,, a die grinder is as loud at ten in the morning as it is at ten at night , but the perceived volume to the neighbours may not be the same and that plays a huge part in keeping the peace [ see what I did there ] distance plays a huge part too , noise is usually measured at 1m away from the source ,, sound basically follows the inverse square law too ,,, intensity id directly and inversely proportionate to the square of the distance ,,,, ie twice as far away 1/4 as loud ,,,, so 7m has a lot of drops in level ,,, hard to make comparisons when figures like that are quoted.

 

[gaz1]

how big is your compressor and do you have a hi flow gun or a low flow gun

you also need to consider air to the gun in short fast bursts they can shift hard ones but ive known them not shift them for a few times

i also know of the heat the nut up with a blow torch and use an impact gun to spin the nut off but ive also known that type to also fail as well

 

[Gooner2826]

sound is strange , 3db is basically double the power , and the inverse is true too ,,, to make something twice as loud takes aprox 10 times the power , a hoover runs about 80db , a fridge is about 40 ...and non of it matters really , its about whats around you , in a quiet house a ticking clock can be heard everywhere , in a shop a 72db radio is background , compressors can be boxed and they dont mind much , but an air die grinder is loud no matter what , and its at a higher frequency and that travels differently than the lower frequency of a compressor .
double glazed windows and insulated walls will help , but so will a bit of consideration ,, a die grinder is as loud at ten in the morning as it is at ten at night , but the perceived volume to the neighbours may not be the same and that plays a huge part in keeping the peace [ see what I did there ] distance plays a huge part too , noise is usually measured at 1m away from the source ,, sound basically follows the inverse square law too ,,, intensity id directly and inversely proportionate to the square of the distance ,,,, ie twice as far away 1/4 as loud ,,,, so 7m has a lot of drops in level ,,, hard to make comparisons when figures like that are quoted.

Yeah my neighbours are my biggest consideration in this, its the only reason I’m looking at the aircat stuff because it’s quite a lot of DBs quieter than other air tools, and in use under load they’re of similar noise to my cordless which haven’t caused any major issues so far.

It’s the compressor that’s the sticking point for me really, because it could be running for minutes at a time whereas the tools are mainly in short bursts

Compressor is not the only noise.

 

[Erie Fred]

Yeah my neighbours are my biggest consideration in this, its the only reason I’m looking at the aircat stuff because it’s quite a lot of DBs quieter than other air tools, and in use under load they’re of similar noise to my cordless which haven’t caused any major issues so far.

It’s the compressor that’s the sticking point for me really, because it could be running for minutes at a time whereas the tools are mainly in short bursts

Yes, however, a simple low chug-chug-chug is one thing.
a screaming dental drill sound erratically is another.

 

[Jackimus]

^ A belt-drive compressor is a surprisingly inoffensive noise for how 'loud' it is on paper, but the cut-off tool on the end of it? A godawful scream.

My money would be on sticking with the belt-drive, isolating it well and putting some DIY acoustic panels on the surfaces immediately around it to kill some of the first deflection of the sound wave.

 

[Bdog507]

Good morning all.


That spec for that Hyundai compressor appears to be misleading. They quote the CFM FAD (free air delivery) at 22 CFM, but the displacement is quoted at 17.31 CFM.
That's probably the wrong way around. As displacement is the volume that the pump actually shifts, & FAD is what comes out if the tank.
Also they say it's duty cycle is 65% which seems unusually high for a piston compressor. They're usually between 35 & 40%.

It's worth noting that most smaller compressors won't run an air tool for any length of time. No matter what the tool manufacturers claim the tool consumes in CFM.
Most air tools need 90psi to operate correctly, & despite whatever FAD the compressor manufacturer claims the compressor won't keep up.
My old 150 litre ABAC compressor will drop to 60psi or lower when using say a power file or drill. At that point a power file is scraping & not sanding, & one would be better of twisting a drill by hand.

Still, the Hyundai compressor looks like it would be good for home use, & it would certainly be quieter than my ABAC, for it's very loud. Fortunately it's not an issue in my workshop, although customers often jump when it cuts in.


Cheers.


Stewart.

 

[dave h 2]

Edit and paste warning for your advert.
So sanity check
FAD is not CFM. Like American HP in the 60'S cars CFM assumes no losses at all, FAD is the compressor rolling road output.
CFM is always bigger than FAD.
2hp produces 9CFM ish so the 4hp should give you double so the 17.31 will be the correct CFM, 490L/min also matches 17.3 .
Air flow FAD in both metric and imperial is wrong and you need to knock off 3 or 4 off the 17 CFM number for the FAD.