Thread: Air compressor enclosure

Originally Posted by Spyro

So I ran the compressor a couple of times from completely empty to full, and I noticed a) it doesn't take any longer than normal, and b) the temperature inside the enclosure only goes up from 25C to 29C, which is well within spec. I mean it was warmer than 29C inside the shed the other day and everything worked fine.

I have a few mechanics at work and I asked them their opinion, half of them said "she'll be right mate, do nothing" and the other half said "she'll crap it in 3 days, start drilling airholes now"
Another option is to attach a hose to the air filter and drill a hole for the hose only, so at least it can get fresh air from outside to compress. But the response from the mechanics was "sucking air through a straw will only make it worse".

What are your thoughts?

It depends what your duty cycle is going to be like and how you use your compressor.

I doubt a single recharge every half an hour or so is going to do much to it but if your need to run it continually for any length of time you are more likely to cause long them damage.

I would do some testing, say completely discharge the tank and leave the outlet fully open for about 5 times the length of time it takes to recharge, and monitor the temperature it gets up to.

BTW you really should be monitoring the temperature of the compressor head and not just the air in the enclosure because there is a significant lag between the two temps..
Leave the box open and measure the compressor head temperature and then do the continuous "5 times the time it takes to recharge" temp test.
Then put the lid on the box and do the "5 times the time it takes to recharge" temp test.

FWIW I have a Twin V 2, 4HP compressor inside an enclosure outside my shed that is vented using a 4.5" 240V computer fan that kicks in when the compressor starts and runs for 10 minutes after it switches off. I don't remember what temperatures the head tests showed ( I used an IR thermometer gun for those) except that temp with the closed doors and fan on was slightly lower than with the doors open and fan off. I attributed that to the fan being big enough to provide significantly better forced ventilation versus the passive ventilation it would otherwise achieve.

Originally Posted by BobL

It depends what your duty cycle is going to be like and how you use your compressor.

I doubt a single recharge every half an hour or so is going to do much to it but if your need to run it continually for any length of time you are more likely to cause long them damage.

I would do some testing, say completely discharge the tank and leave the outlet fully open for about 5 times the length of time it takes to recharge, and monitor the temperature it gets up to.

BTW you really should be monitoring the temperature of the compressor head and not just the air in the enclosure because there is a significant lag between the two temps..
Leave the box open and measure the compressor head temperature and then do the continuous "5 times the time it takes to recharge" temp test.
Then put the lid on the box and do the "5 times the time it takes to recharge" temp test.

FWIW I have a Twin V 2, 4HP compressor inside an enclosure outside my shed that is vented using a 4.5" 240V computer fan that kicks in when the compressor starts and runs for 10 minutes after it switches off. I don't remember what temperatures the head tests showed ( I used an IR thermometer gun for those) except that temp with the closed doors and fan on was slightly lower than with the doors open and fan off. I attributed that to the fan being big enough to provide significantly better forced ventilation versus the passive ventilation it would otherwise achieve.

Yeah I only really use it for nails, blow gun and air brushing, so it hardly ever starts more frequently than half an hour.
The temperature goes up really fast though, today by exception I used it to try some wood carving with an angle grinder as an experiment and it ran continuously for about 10 mins or so, and it got to 35C straight away so I stopped it.
It's easy to add a fan, I was thinking maybe at the back under the bench, and facing out to suck the hot air out of the box. I'm just not sure I need to, and most importantly I don't want to compromise the noise reduction result which is currently excellent.

Originally Posted by Spyro

.....And now here comes the complicated part. Between the box and the back wall under the bench there is a 50mm gap. This was intentional as I was going to build there a little maze, like a muffler sort of thing for some ventilation for the box that wouldn't allow too much of the noise to come out. The question is though, do I need to? or am I over complicating things for no reason?

The box is by no means air tight, it kinda "breathes" a little bit through the holes I've already drilled for hose & power cable, and probably through the lid that just sits on top, I haven put any seal strips or anything.
.....
Spyro

Hi Spiro

Not just complicated, but very difficult in practice. If you get the "baffles" right then you may halve the noise; if you get them wrong then you may create a trumpet.... And if it is not airtight then noise can get through.

Do you know anyone who builds stereo speaker boxes - they generally know a lot about accoustics and may be able to help.

Some years ago a company I worked with had a "sound proof" conference room built at a cost of well over $100,000. The walls were made from accoustic panels about 3000x1500x25 mm; alternating veneers of lead sheet and plastic foam. The panels might have been sound proof, but the aluminium extrusions that held them together and the air conditioning ducting was definitely not sound proof. It was a total failure.


Cheers

Graeme

Originally Posted by GraemeCook

Hi Spiro

Not just complicated, but very difficult in practice. If you get the "baffles" right then you may halve the noise; if you get them wrong then you may create a trumpet.... And if it is not airtight then noise can get through.

Do you know anyone who builds stereo speaker boxes - they generally know a lot about accoustics and may be able to help.

Some years ago a company I worked with had a "sound proof" conference room built at a cost of well over $100,000. The walls were made from accoustic panels about 3000x1500x25 mm; alternating veneers of lead sheet and plastic foam. The panels might have been sound proof, but the aluminium extrusions that held them together and the air conditioning ducting was definitely not sound proof. It was a total failure.


Cheers

Graeme

Hi Graeme

I actually bought a book on speaker building and read it (it's one of many woodworking projects I'm interested in) and also did a bit of research on isolation boxes and various solutions that allow ventilation and restrict noise. It seems the most interest and technical knowledge on the matter is in the music industry with recording studios, mini solutions for the house etc. But you are spot on, it's neither simple nor cheap, and the secrets are not freely shared either, it seems that people who have found efficient solutions are trying to sell them in one form or other. Which is fine, but it doesn't help me very much, I've already spent more time and money on this box than the compressor is worth LOL
But it's all fun

My solution is to take a step approach, monitor the temperatures in the chamber for the kind of use that I normally do and then consider drilling one very small hole at the time as I need them.
For the time being with normal use and no holes at all I don't actually exceed 30C so I decided no holes for now. Interesting experiment though, I want to see if the compressor develops any problems like that.

Sounds good, Spyro

As you get into audio you will encounter Thiel-Small parameters. They are brilliant tools to use in predicting the performance of a speaker enclosure design. You can download software so you do not have to do the maths - well worth knowing.

But Thiel-Small tries to optimise enclosure performance across the range of human hearing, say 20 to 20,000 hertz. You want to minimise it. This is a valid but perverse way of using T-S.


Good Luck

Graeme