I have one like that, albeit with a different brand name on it. I bought it for the same reason: noise. Whilst it is not silent, it much quieter than my previous “standard” compressor. You can hold a conversation when it is running and with a little sound-deadening material around it, it would be even quieter. For the money that I paid, I am very pleased with it. I use it in the evenings with a clear conscience.

James

The bigger the receiver the longer the engine will have to run to fill it – conversely, with a smaller receiver the engine will run for a shorter period, but with greater frequency if you keep emptying the tank..

..so you need to consider how much air you think you will be using in ‘a session’ to see which you need..

A Bambi, with its fridge compressor style enclosure, is probably the quietest closely followed by the similar industrial rated compressor and reservoir units from other makers such as Jun-Air. to name one I have personal experience of.

But they are expensive.

The affordable twin exposed diaphragm compressor beasts, like that one, are rather noisier than the better versions of the small suitcase stye compressors. My FIAC Compact 106 claims 57 dB but FAD is low at 3.5 cfm. and the tank is small. Don’t really hear it start and stop when running my Bijur mist style lubricators on mill and lathes.

But the suitcase compressor market is total minefield with some remarkably noisy devices sold on the basis of small size only. Some are little more than uprated car tyre inflators and really should come with ear defenders. Brand being no protection. Looking at you Makita and the normally reliable LiDL Parkside offering proved far louder than friend could tolerate. Funnily enough the Parkside one made a one time only in the middle of LiDL. I suspect my friend wasn’t the only one to sling it back same day.

An oldie, but goodie, is the baby Hydrovane PR303E unit made for Binks Bullows continuous air feed compressors. Possibly the quietest of the lot due to the near continuous airflow and, apparently, built to exceed the 100 years and a day life of Wendell Holmes famous One Horse Shay. If you want one prices are all over the place from daydream £350 + on E-Bay to £20 at the bottom end of Facebook marketplace, back of a charity or used tool shop.  Need to DIY a tank though and only 40 psi or so.

Fitting a decent air filter box with reasonable volume inside damps out the induction pulses inevitable with a diaphragm or piston compressor which makes a useful reduction in noise. Steal the airbox off a small car or adapt a (tubular?) filter. OK it’s a much bigger unit but many years ago I put a SAAB 9000 air filter between the arms of an Atlas Copco KE series Vee twin compressor which seriously reduced the noise. Memory suggests down to little more than twice as loud as the Hydrovane that replaced it.

Clive

I have the 50 lts  twin pump Hyundai and use it to run models as well as chip blasting on the CNC and blowing down. Only time I know it is on when machining is when the cutoff cuts in. About the same sort of noise level as a washing machine makes so you can talk over it OK.

Well Hyundai claim 60 dB for the HY7524 which is rather quieter than most washing machines where anything below 70-75 db is considered quiet and 50-55 dB super quiet. My Miele W1 Classic washing machine claims 48 dB during wash cycle and 72 during spin. It is noticeable during spin but not during wash unless standing right next to it.

At 57 dB my FIAC suitcase is half as loud as the Hyundai. The little Hydrovane PR303 I also have is a bit quieter still, no specs but subjectively it feels like around 55 dB.

Bambi claim 40 dB. A Bambi is completely unnoticeable to me and, probably, everyone else who doesn’t have ears like a bat.

The environmental folk reckon 50 dB ± 5 is satisfactory background noise level for domestic and office situations. Preferably nearer 45 if doing a lot of talking and 40 dB where serious concentration is needed.

Subjective assessment is hard because not only is dB is a logarithmic scale where 3 dB equates to doubling of sound power levels but also the standard human ear signal exploitation kit has some pretty serious active sound processing capabilities built in. Which really really upsets the correlation between “measured sound power” and “sounds like”.

Clive

I’ve got the smaller Hyundai one – it should be adequate for your needs I should think, and it’s very quiet – not silent, but if the neighbours complain, tell them not to stand next to it.

4 Hp, 13A plug. NO ! Noel.

Almost certainly rated by input current rather than output shaft mechanical power. So 3kW will be fine.

Diaphragm style compressors have much lower starting loads than conventional piston ones. Power draw at peak pressure is generally less too as they don’t do as well at producing high pressure air.

Back in the days when I first encountered them, maybe 45 years ago, it was tacitly assumed that 60 psi was about the best you could expect. It was also reckoned that trying to use them on a tank was optimistic and for best results a continuous  air draw tuned to give the right pressure was the way to go. probably why the opposed twin was the favoured configuration. Mostly considered an interesting and relatively inexpensive device for certain appropriate employment.

Clearly the state of the art has improved somewhat in the intervening years.

Back then suggesting that such machines could ever be competitive with small piston type compressors on tank filling duties would have raised serious questions about intellect, sanity and smoking habits. Ultimately it’s much harder to get the minimal clearance volume and high compression ratios needed for sustained delivery at higher pressures from a diaphragm than from a piston and cylinder. Which both tends to cap the power draw and require multiple small “cylinders” for larger FAD.

Clive

Um, 1HP = 745W so 4HP is 2980W (or 3000W if you prefer the 1HP = 750W definition) and 240V x 13A = 3120W.

So, marginal on a 13A plug, except 13A fuses can take it; they don’t blow at 13A!  Fuses made to BS1362 will pass 20A continuously forever, allowing brave souls to power 4 or 5kW electric welders off a 13A socket, even though best practice says the circuit should be uprated.

How long the heat caused by transferring excessive power through the wire, fuse and socket has to dissipate between bursts of consumption matters.   A 13A compressor running for 5 minutes in every 20 has a 25% duty cycle, roughly equivalent to 3.25A continuous,  hardly scary.  However if the same compressor is run continuously by the operator, then he should worry about damaging the socket and/or house wiring.  House wiring can be overrated too, but wire buried inside a well-insulated wall will get much hotter than the same strung in air.   Setting fire to the house will ruin your day, and don’t expect the insurer to pay up if they discover an irresponsible electrical optimist caused the problem.

Usual warning about my maths!

Dave