Hello everyone, in this particular tutorial I will be showing you how to repurpose this broken air compressor into a portable air tank, also known as an air pig. This little compressor is probably close to 10yrs old and unfortunately has seen better days. I did disassemble the air compressor to find the connecting rod for the piston on the pump had broken. Some models may have replacement parts available, other times you can purchase a new pump assembly or even just purchase another air compressor if you can find a great sale. However I already have a larger air compressor and instead of throwing this one way, I can repurpose it to a new use for only a few dollars. A new compressor would have been around $75 on sale for me vs a couple fitting (the rest of the material I had laying around) which was around $10.
- adjustable wrench
- teflon tape
- cleaning solvent
- brass wire brush
- old air compressor
- air gauges
- relief valve
- Schrader/sniffer valve
Step 1: Motor & Pump Removal
First we’ll start with disassembly, stripping this down to the bare tank so we known exactly what we need and how to go about it. Remove the four screws holding on the plastic motor and pump cover. Disassembly procedures will vary between air compressors and even if you just have an old air tank you’re reusing, you can use this tutorial as well. Remove the handle so the cover can be fully removed.
Once that cover is flipped over, the on/off switch and fuse needs to be disconnected, both use spade connectors. You can save the electronic components for a future project, the new air tank will no longer require them.
To remove the steel line which supplies air to the tank from the pump, remove the line directly from the tank. If using an adjustable wrench, make sure it’s a better quality tool with tighter jaws as they can flex and damage the hex on a fastener or fitting.
Now for removing the motor assembly, there will be four phillips screws which holds this on the tank bracket. The disassembly process is fairly straight forward, no special tools are required and most of these old components will be thrown away. I may save the motor for another project.
As you can see in the photos, the connecting rod is broken for piston. Some of it has already been disassembled from previously when I thinking about repairing the actual pump. I could have possibly made a new connecting rod, but that could have been very time consuming.
Step 2: Breaking Down the Air Fitting & Preparation
Removing these fittings can be somewhat of a puzzle. When certain fittings are rotated, they may have interference with other components.
I will be reusing the old pressure relief valve, this is needed so we do not over pressurize the tank which can be safety hazard. These valves will have a rating, this one is rated at 115psi. Once the tank is pumped up over 115psi, the spring loaded valve will activate and release the excess pressure.
Various sized wrenches will be required to remove the old fittings and as long as they’re in good condition you can reuse them. Liquid thread sealant was used on some parts from factory, some fittings were reworked over the years and had a sealant called pipe dope.
Considering we have three connections in the tank, the largest connection will have the lowest restriction and used for the main air line hook up. The other two are the same size, one will be used to pump up the tank and I would like to reuse the regulator, so that will be for the third connection.
The paint is still in good shape on this tank, so no real need of repainting it.
Step 3: Installing the Schrader Valve
Installing the Schrader valve, also referred to as a sniffer valve which you can find in the plumbing section at your local hardware store. This one came with cap that removes the inner valve too.
Instead of pipe dope, I’m using teflon tape. I find it’s nicer to use as you don’t have a sticky mess afterwards. When looking at the fitting from the threaded side, wrap the teflon tape 2 to 3 times in the clockwise direction. If you were to do this in the counter clockwise direction, the tape would unravel and not seal. After the wraps, break the tape, ensure it’s not covering the hole and install the fitting.
Teflon tape serves two purposes. One is to help seal the threads and the other is to provide lubrication, ensuring the fittings can be tightening, therefore increasing the seal of the connection. I’ll explain the type of pipe threads in a moment. Make sure the connection is tighten, but do not over tighten it to damage the threads in the fitting.
Step 4: Mock Up
I also needed to purchase a couple more fittings, one being a bushing which reduces the size of a threaded hole and the other is a hex nipple, basically having two male threaded ends.
Now to do a quick mock up of everything before applying teflon tape so I know exactly what I need and how everything sits. This will also allow me to determine which parts need to be connected so there is no interference during assembly. All the old pipe dope was cleaned off, I let the fitting soak in a wax and grease remover solvent over night and then cleaned the parts up with a brass wire brush.
This can get confusing for thread types, so I’ll try to explain this as easy as possible. The threading using on this compressor is national pipe thread or NPT for short. This is a US standard that uses a tapered thread. This is not to be confused with nominal pipe size or NPS for short which uses a straight thread. When looking at a fitting, you will need it’s tapered. So we will need MIP or FIP fittings. MIP means male iron pipe or male international pipe. And FIP means female iron pipe or female international pipe.
Step 5: Final Assembly
Now for assembly, applying teflon tape to each male fitting so the threads achieve a proper seal. Trying to use the least amount of connections as possible, this will reduce the change of any leakage as well as reducing costs if you are having to buy all the parts. Again only 2 to 3 wraps of teflon tape is all that’s needed. Any access tape exposed to the outside of the fittings can be easily removed which I’ll show towards the end of the video.
The relief valve gets installed on the largest connection to ensure there is no restriction which may delay it’s operation. When pumping up the tank, we can also monitor the gages on the tank to determine it’s current pressure.
Now for pealing off the access tape. Once everything has been tightened down, find the end of the tape and peal off. The last threads should have helped up the tape on the outside so it removes easily. The teflon tape is much easier to clean up than compared to pipe dope.
I had to replace the quick disconnect fitting, for some reason the other was sticking open and not allowing the tank to pump up. And then reinstall the carrying handle.
Step 6: Testing
For a test, pump up the tank using an air compressor and then let the tank sit for about 10min with pressure. Monitor the pressure gauge for any droppage which would indicate a leak. A leak can be found using a spray bottle with a soap and water mix. Spray it onto the connections and watch for bubbling. To repair the leak, try to tighten the connection first. If that fails, disconnect the connection, clean off the old teflon tape and inspect for damage. Replace the fitting if required or apply more teflon tape and reinstall the fittings.
The tire pump gauge can be used as a reference, as you can see we have the correct reading on the tank gauge too.