Part 5 of 5 - Building the sound proof enclosure for my air compressor

DOES IT WORK?

It has been a fun and worthwhile exercise of making the soundproof enclosure as well as documenting it. When I first started on it, I found lots of information on the net, but all scattered everywhere. I hope that my blog will help others in making a similar enclosure, I know you will be pleased because it has really worked wonders.

No longer will I be frightened when the compressor motor kicks in. I did another sound test of the completed enclosure to see how the noise (or absence thereof) is like from outside my garage door. Compared to before, now I can hardly hear it, I have toreally strain to hear it. It is not by any means a silent compressor (like what they use in dental clinics), but it is now definitely a quieter one. In fact, my auto garage door closer is even louder than this so I am a happy camper.

Lessons Learned / Recommendations

1) Start with getting the quietest air compressor you can find. If you can get a silent air compressor, then you won't have to go through the trouble of building an enclosure. The only problem with them is typically they have low CFM ratings, and that means that I can only use only one air tool at a time or cannot use it for high CFM tasks such as spray painting, orbital sanding, etc.

2) I have read somewhere that cast iron pumps are quieter than their aluminum cousins. I cant really confirm this, so hopefully this is true and someone will confirm for me.

3) Some air compressors have larger motors and pumps and that allows it to rev at a lower rate. The lesser the RPM the quieter it is.

4) Get yourself an intake filter silencer, like the Allied Witan Atomuffler I used in this project. I would have been happy with just the silencer. But coupled with the enclosure, it really works wonders.

5) With the way I am using the compressor (where the motor kicks in maybe 4 times an hour), you may get by without the AC fan. In my setup, the fan has never really turned on as the thermostat doesn't reach the setpoint (~40degrees Centigrade). But if you are using the compressor heavily, like in spray painting, then the cooling fan is definitely needed.

6) All in all, the multi-pronged approach to soundproof the air compressor enclosure has been very successful.

Part 4 of 5 - Building the sound proof enclosure for my air compressor

Google is my friend

When I embarked on the task of sound proofing/noise reduction for my air compressor, I didn't really know anything about sound proofing. I thought all you needed to do was to put it inside a box and then that's it. Little did I know that there were quite a lot of details to learn and apply to effectively soundproof my enclosure. And I thank Google for facilitating all my research. As there were several things that you can do to combat noise, I decided to apply a multiple-pronged approach.

SOUNDPROOFING AN AIR COMPRESSOR

Use of a sound barrier material

Firstly I decided to use 18mm MDF as the walls for the compressor enclosure. From my Google research, I found out that MDF had an STC rating of around 29, which is pretty good. In addition to this, I also used mass-loaded vinyl (MLV) , a heavy vinyl sheet which I attached to the inside wall of the enclosure. It is also known as a Flexible Noise Barrier. Here in Australia, I used an MLV marketed as WaveBar from Pyrotek. This thing is heavy at 8kg per square meter, and that's why it works. It is also very easy to apply, I just used screws for fixing to the inside wall. This material has an STC rating of 30. I got the WaveBar roll from Clark Rubber.

The photo shows the inside of the enclosure lined with 8kg/sq. meter WaveBar.

Use of a sound absorption material

I got these MLV + Acoustic Foam from Jaycar Electronics. They did not say what it is, but they look very much like WaveBar, although it is not that heavy at 4.5kg per square meter. I used some of these as they are laminated to acoustic foam material, which helps in absorbing sound to get rid of reverberations and echo. The foam would also have a dampening effect on the MDF.

Use of vibration dampening material

I got some vibration dampening rubber pads from Clark Rubber. The air compressor do not have direct contact to the concrete floor of my workshop. Surprisingly, you can actually hear the difference straight away after using these.

Input and Output sound deadening baffles or muffler

If you have read my previous post, this mentioned about using a labyrinth design for the input and output muffler. I had also used some acoustic foam in the inside surfaces of the muffler to control echo.

Use of Intake Filter Silencer

The intake side of the air compressor is what makes the most noise. To combat this, the Intake Filter Silencer was invented. It works the same as an exhaust muffler, only the air direction is in reverse. Same principle, let air pass through, but block sound. I did some inquiries, and found out that my choices for intake filter silencers are limited here in Sydney. The first is the silencer from a company called Solberg. They can be available in Sydney, but the bloke I spoke to on the phone wasn't particularly helpful so I tried another company.

Next I inquired about the intake filter silencer from a company called Allied Witan , called Atomuffler Filter Silencer. I couldn't find any literature about the amount of sound it attenuates, but it works, and it works really Good. Surprisingly Good.

Part 3 of 5 - Building the sound proof enclosure for my air compressor

Access to the air compressor

The soundproof enclosure has 2 openings, a small door on one of the short sides allowing me to access the air compressor say when draining water in the air receiver, or when it will need to be transferred to another place, or when it needs some cleaning. The second opening is the large heavy lid on top. Nice and heavy, so that it will not vibrate when the compressor is running. I have also installed the exhaust baffle on this lid, but on the inside. A hole was made on it for the air compressor exhaust. I open the lid when I need to turn ON or OFF the compressor, to access the pressure ball valve, adjusting and cleaning the air intake filter, etc.

240V Power point

I have designed the enclosure so that there is only one electrical wire coming out of it. Remember that I have to power a 240V air cooling fan, the air compressor, and a 12VDC power pack for the electronic thermostat (which I use for controlling the fan). All these items get their power from the power point which I positioned inside the enclosure. I just got a 2-socket 10A 240V power point from Bunnings and made my own extension lead. Please remember that any work with live mains will have to be done by an electrician or a suitably qualified tradesman.

Junction box and Cooling fan Thermostat

Initially my design only had a 240V air cooling fan continuously operating. Although this is fine, it is a waste of energy though. And a little annoying too, as the fan I used, although not noisy, gets in your nerves after a while. Another trip to Jaycar solved this as I was able to secure a 12VDC electronic thermostat in kit form to control the fan's set points. It only took few minutes to solder the kit and a bit more to do its enclosure. The idea is - to turn on the fan when it reaches a certain temperature and turn it OFF once it reaches room temperature. Once I get hold of a digital thermometer, I will be able to calibrate it properly. The purpose of the junction box is just to neatly wire all the electrical bits together.

Air Filter/Regulator

The air compressor originally had an SMC air filter and regulator attached to it. But since this will now be living inside the soundproof enclosure, they will have to be accessible from outside the box. I just moved the filter/regulator outside the box and a quick trip to my local air tool shop to get a quick release fitting so that separating the compressor from the box will be easy. Have a look at the photos to see what I did to allow this.

First photo shows the soundproof enclosure showing the top lid open. The cooling fan, powerpoint and air hose positioning displayed. The blue airhose is terminated by a quick release fitting at the compressor side. The second photo shows the outside of the soundproof enclosure to show the location of the air filter/regulator. The filter is output to a Y quick release connector. One is going to the blowgun (or any of my other airtools), while the other one will be constantly connected to my underpinner.

Part 2 of 5 - Building the sound proof enclosure for my air compressor

The plan for the enclosure will be a box without the bottom panel. There will be 1 door on one side for easy access to the compressor when draining it and a lid on top. The compressor will be resting on the concrete floor, as I would think that if it was resting on the enclosure might create more noise due to reverberation and vibration. Making the box is one thing, now we have to design into the enclosure a mechanism for cool air to ventilate inside and the warm air to be let out ensuring the compressor does not overheat as it cycles. All the while keeping noise inside. The lid on top of the enclosure is where the output baffle will be situated. The input baffle is located opposite the side of the door.

Making input and output sound baffles

I have done a bit of research and found several ways to enable ventilation and soundproofing at the same time, and eventually decided that the easiest is to build input and output baffles using the labyrinth method. This is essentially a muffler design which works because sound waves do not like to go around bends, but this is fine for air to travel through. Basically the more bends the better. Shown in the photo is the input baffle/muffler where the inside surface is lined with some noise absorbing foam.


I could have been more liberal with the foam but I ran out. You can also see the round hole I created for the cooling fan. For the fan I used a 240V AC cooling fan. The model I got is a 105 cfm capacity which I got from Jaycar Electronics. This enables the air inside the enclosure to be replaced 5 times every minute, ensuring more than adequate ventilation. The fan is connected so that it pulls air into the enclosure and forces air out through the output muffler. The output muffler is very similar in design to the input baffle, but this doesn't have a cooling fan installed. Just a hole on each end of the muffler. Next photo shows the output muffler with the rectangular airway.


The input and output baffles will now be attached to the enclosure from the inside. I used small angle brackets for these. The next photo shows a hole on the outside of the enclosure. This hole is for the input baffle. So the air will be sucked through this hole, through the labyrinth inside the input baffle, through the fan, then into the enclosure. As there is no other way for the air to go, it then goes out through the output baffle, which is located in the lid on the top panel. I have tested this and it works really well, ventilation-wise that is. I can't wait to see if the sound deadening actually works...

Part 1 of 5 - Building the sound proof enclosure for my air compressor

As I mentioned in my previous post, I am building a sound proof enclosure for my new electric Pilot Trademaster TM12 air compressor. I don't have access to a sound meter, but this thing is loud. I would just estimate it to be around 80db. When the motor kicks in, I cannot hold a conversation without raising my voice considerably. A consolation is that when this happens, it only takes about 45 seconds for it to fill the 58 litre air receiver. My goal in this exercise is to reduce the sound output so that first, I do not disturb my neighbors as I make my frames at night, and second, I don't crap my pants when the motor kicks in.

First of all, I will give you a bit of a background about where this compressor lives so that you will appreciate my reason of making the effort to build this enclosure. As you know I have converted my garage as my framing workshop. It is a 2 and a half car garage, and my workshop takes up 1 and half area, so that I only have space for 1 car. So yu can imagine that with the compressor being in a confined space as this, and with the metal garage door that echoes like crazy, the noise is amplified such that it makes so much disturbance, not only to me but most importantly to my neighbours. As a test, I tried standing outside my garage door while the compressor motor is running, and even with the garage door shut, it is quite loud and unacceptable if you ask me.

Making the basic enclosure

The first step in this project is building the base enclosure using 18mm MDF (medium density fibreboard). MDF sheets in Australia come in different thicknesses. The thickest being 36mm, then 25mm, then 18mm, 16mm and so forth. In terms blocking noise, the thicker the better. I'd like to use the 25 or 36mm but these were too heavy. I thought it would be very hard for me to build the enclosure by myself. I decided on using the 18mm sheets, as it is still thick enough for my purpose. I have read somewhere that 16mm MDF sheets have an STC rating of 29. Sound Transmission Class (STC) is the measure of the sound blocking property of a "wall", such that a STC 30 material typically reduces the decibel rating of the noise by 30 db, STC 20 by 20 db and so forth.

In building the base enclosure, I went the easy way and went to Mr Ply & Wood, a sheet material supplier in Australia. Gave them the measurements of the panels basing from my drawing plans. They then find the optimum sheet size that will fit it with the minimum of wastage, plus a small cutting charge. The result is professionally cut MDF sheets, that will all fit in my car and ready to assemble. In addition to the MDF sheets, I also needed 70mmx35mm structural pine timber which serves as the skeleton for the enclosure.

The following photos show the construction of the enclosure using the MDF sheets and pine timber.

Soundproof enclosure for my air compressor

The arrival of my new pneumatic underpinner meant that I needed to be familiar with using and maintaining an air compressor. I got a 12cfm Pilot Air compressor to power the new underpinner as well as my other air tools. Although this capacity is more than enough for my use currently, I hope to still be using it for years to come even later when I will inevitabley have more air requirements. Having not had used an air compressor before, I was surprised at how noisy it iwas. Although my petrol lawn mower is much much noisier, everytime the compressor motor decides to kick in, no fail, always, always scares the hell out of me. Man that's loud! Add to the fact that I mainly use it during weekday, or weekend nights. Plus my garage door is metal which creates a lot of echo in effect amplifying the noise more. I'm sure the neighbors won't be happy. Stay tuned to see how I go in creating a soundproof enclosure for this beast. I already got the drawing plans, and materials ready. I should be able to finish most of it in 1 day. Maybe...

My trusty old Cassese CS88 is now for sale

It's been a long while since my last post. Since then, I have now upgraded to a new underpinner to replace my trusty old Cassese CS88. Although I am very happy to receive the delivery of the shiny new pneumatic Cassese CS 199MXL, I am a bit sad to think that I am letting my old v-nailer go. Although it is only a manual equipment, it is very well engineered so that it can handle almost anything I ask it to join. To be sentimental about it, it will always in my fond memories as it helped me graduate from a 'hobby' framer (using hand-tool joiners) to being a full -pledged 'professional' picture framer. It has never failed me, even though I might not have given it the proper maintenance care it deserved. It just keeps on joining... and joining... and joining...

If anybody is interested, my CS88 is now up for sale in ebay.