Air-Craft.net Sil-Air15D Silent Compressor

[Mike]

15D Silent Compressor
Werther International

Italian company Werther make a large number of compressors both under their own name, and for other companies around the world. Their Sil-Air brand is well known as being amongst the quietest compressors in the market, being somewhere around the noise levels of a very quiet computer at 28-31db. This renders them almost inaudible in a quiet room, and once you add some background noise or music, you'll not hear a thing until the tank is full and the relief-valve blows off.

The hobby end of their range are the Sil-Air 15 models, and they start with a small receiver tank of around a litre to remove both the need for the motor to run constantly, and to remove the pulse from the airline that can affect the spray pattern of your airbrush under some circumstances. The Automatic compressors have a cut-off valve that stops the motor running when the receiver is up to pressure, and re-starts it once the pressure has dropped past a certain level. This makes for an efficient set-up that requires minimal input from the user other than to set the pressure they require. They all have on/off switches, an air filter to keep contaminants from entering the receiver, and an adjustable regulator with built-in moisture trap. The compressor within is a refrigerator type oil-filled unit, which requires the best part of a litre of oil for operation, and this should be changed annually to prolong reliability. It also means that you should keep the compressor on a level surface, and always upright. For transport to the user they are supplied drained of oil and with an oil bottle supplied in the package to refill it prior to its first use, and if you move house or transport your unit further than the end of the garden, it's a good idea to follow their lead.

Sil-Air 15D
The D model is larger than the others, and has a much bigger receiver that holds up to four litres of compressed air at up to 87psi (6bar). It is roughly double the height of the smaller models, and weighs in at an impressive 18.3kg, which makes the user glad there's a carry-handle on the top to lug it about. It has rubberised feet that dampen any vibration against the floor, a large thick-gauge steel cover that is powder coated and bolted to the chassis onto which all the other parts are attached. Removing the cover is simple, requiring the user to undo just 6 bolts, then lift off the part carefully for easy access to the internals.

The compressor is hidden away inside the rear of the unit, and has a removable lid that is held in place by a retention strap, which can be unscrewed to open the compressor to add the correct quantity of oil. It's much easier than trying to drip it in via the oil inlet on the side, which is at a curious angle, and a bit narrow, so once you've checked on how that affects your guarantee, unscrew the lid and be done with any faffing. There is a glass bubble on the rear of the compressor under the electronics box that allows you to check the oil level at a glance, which is especially handy if you are refilling it. Just remember to allow the fresh oil to settle into the workings before you judge whether you need more.

The regulator is built into the unit, and therefore protected from any accidental impacts, whilst still being easy to adjust and view. The pressure is indicated on the dial on the left, and adjusted by the black turret-shaped knurled wheel on the top, which can be locked by pressing it down. Unlocking is achieved by pulling up the top section, as you'd expect. The moisture trap is present to retain any water that might condense out of the compressed air, and is made from tough clear plastic to enable easy checking. Emptying the trap is simple, and there is a handy circular cut-out in the bottom chassis to enable you to do this without skinning your knuckles. The on/off switch is located on the front with a yellow sticker indicating its location, as it's quite dark within the cowl and the switch is black on grey.

If you want to empty the receiver tank, there is a brass valve on the front of the compressor, buried away to the left of the on/off switch, and this is operated by a pull-ring that is yanked forcefully to the left to release the compressed air. I had to do this to set up the review pictures, and a small quantity of oily residue splattered the inside of the cover, so if you'd rather keep it clean, just tape a piece of paper to the inside to catch the goo.

The outlet is a standard ¼" male threaded adapter that was already screwed into the female outlet on my sample, and this will fit the majority of modern airbrush hoses without an adaptor. I usually add a little plumber's PTFE tape to stop any leaks, and you can see it wrapped around the outlet in the accompanying pictures.

In Use
I'll start with an apology for the slightly dusty compressor - it's been in use for over a month, so has seen some action in a dusty workshop I have used a Sil-Air 15A for some years now, and it's been an excellent compressor, so I was very interested to see its big brother. Apart from the size, operation is broadly similar, which was good because if it works, don't fix it. The unit is pretty much silent, and once I turn on my music (which I find necessary to enjoy modelling), you only hear the hiss of the receiver cut-off, which as you can imagine takes longer with 2.5 extra litres to fill. I set my pressure to around 15psi while my airbrush trigger is depressed, so that it is maintained during spraying, and seldom have any need to deviate from that pressure if I'm honest. This unit seems to be sealed better than my 15A, which would bleed away pressure over time so that the following day the receiver would have almost equalised pressure. This one is still pretty full the next day, which is an indication of good seals.

Spraying using the Sil-Air is pleasant, as the pressure never wavers, there's no noise, and because of the larger receiver, you know that the motor won't be running in short staccato bursts, thereby extending its life. My 15A gave me sterling service for 5-6 years (I forget exactly) with only oil changes needed, which is a testament to its reliability. It is still working just fine, and on extended loan to a good friend who is a night-owl and wanted to be able to spray while his wife sleeps in the bedroom next door. Apart from the hiss of the blow-off valve, I'm fairly sure you could spray in the same room as someone sleeping, it's that quiet!


Long-Term Use Report (05/08/2016)
I have just finished the annual (ideally!) service of my 15D, and have replaced the oil by removing the cowling and undoing the large oval strap that secures the lid of the compressor. The old oil was decanted into a container for later disposal at the council tip's disposal point. The oil showed very little evidence of use, and was still crystal clear, but a new 500ml bottle of Sincom/32E compressor oil was opened up and slowly poured in, being careful to note the correct position on the clear vision port as per the nearby sticker. With that half-way up it was left to settle a while, checked (no topping up needed), and the top re-installed with a 3mm allen key. I gave the base and interior a quick wipe round to remove any oily residue and dust, then cleaned the inside of the cowl to remove the pressure relief splatter before bolting it back into place on the chassis.

While I had the cowl off, I also installed a T-connector using the following parts from Martin's excellent range of stock, so that I could run two air hoses side-by-side.

3 x 105803 Coupler Male to Male 1/4"
1 x RSC3675922 Airbrush Supply Tee, 1/4"
1 x 125913 Braided Hose 3.0M with Air Control

I wrapped a little PFTE tape around the threads to be sure of a good seal, and everything seems to be working perfectly. Thanks for your help with that little upgrade, Martin!


Conclusion
If you're in the market for a good quality, quiet compressor then look no further. If you're sick of the tiresome clatter of your existing compressor, relax – you've found its replacement. The Sil-Air15D is a capable compressor with a lot to commend it over its competitors, and is priced as such, but as I always say "buy cheap, buy twice". A comparably priced compressor from Iwata retails at the same price, has a tiny receiver, and is quite noisy, so the silence is effectively coming for free. It even has a lot to commend it over its smaller brother, the 15A, in the shape of the larger receiver that makes working that bit easier and less wearing on the motor. There's a relatively small difference in price between the siblings too, so for those extra coins, you can "go large" and know that you're getting something other than a bigger box! Just check it'll fit under your bench.

Very highly recommended. Superb compressors, and with the added back-up of our friends at Air-craft.net in the unlikely event of problems, you'll be glad you bought one.

Full specifications, weight, sizing etc., as well as some more pictures can be found by clicking the Buy It Now link below.

Sil-Air 15D Compressor


Extra Sincom oil

Review sample courtesy of

[John_W]

Links don't work.

[Julien]

They work for me.

[colin]

Me too

[Mike]

Me 3.5... try a reboot or a different browser John. Might help

[John_W]

Thanks. Works now.

[Mike]

Review updated with long-term usage report

[godzilla]

Nice review, tempted to get one myself for the sake of having something quiet. I have a question though, how loud is the relief valve and how often does it open up? I have seen some compressors before where the relief is shockingly loud it makes you jump lol. Ideally I'm looking for one that has some kind of muffler or something

[Kev The Modeller]

I've got the very same compressor, had a it a few years now never missed a beat and is almost silent, your fridge makes more noise.   It's only the hiss of the receiver cut-off which is quite loud when you first hear it, you can muffle it but I don;t bother.  

 

As you Mike I got mine through Martin at Aircraft    

Edited June 19, 2018 by Kev The Modeller

[Mike]

Still loving mine too

[Mick4350]

It's a shame that they can no longer ship them down under.

[TommyOneTwoFour]

These reports confirm the positive things I heard and read otherwise.

If I were to go for something new, it would probably be one of those Sil-Air's.

However, as I always use my Wiltec spraybooth along with the airbrush (which is louder than my current compressor), there is no big sense in going for a new compressor just because of its silence...

Another thing comes to my mind about these oil-operated compressors. I once read that, as they are filled with oil, naturally, small particles of oil will always be contained in the compressed air. Sounds logical to me, the point is, can it be noticed to some extent, did anyone using such a compressor ever find some of those oil particles on their model, mixed with the paint??

[bmwh548]

In theory the particles should just lay down on the bottom of the tank, in practice I've had some oil in paint 2 or 3 times. Very pleasant when it's in the topcoat as you can imagine. Haven't had any issues since I added a moisture trap right before the airbrush. Not sure if that's the reason or just a coincidence.