Well you just purchased your Air Compressor and new Tool Set and maybe your manufacturer was nice enough to include a basic hose and a few adapters to get you started but there are a number of features that you should consider to get the most out of your tools.
For most non-commercial applications when buying hoses you will be looking at a range from 1/4″ at the small end to 1″ at the very high end.
The size of hose that you need for your compressor should be listed in your instruction booklet but there are situations where you might want to upgrade.
If you have a standard 5 hp compressor and you will be using it to run only a single general duty mechanic tool at a time a 3/8″ inch to 1/2 inch braided line is what you will need.
Remember the larger the volume of air needed by the tool will require a larger hose line.
Your restriction will be found on your compressor at the outlet of your air pressure regulator. If the outlet fitting is 3/8 then that is what you buy but there is a reason to buy a larger line if you can justify it.
As you can imagine a larger hose line will allow a higher flow rate at a specific pressure. If you are using your tool some distance from your compressor at a high pressure over long periods of time upgrading to the next higher line size will provide a longer life for your hose because the larger line will use heavier braiding and allow your tool to obtain air at a more consistent rate.
On the other hand if you are working on a roof then you want the lightest air line that you can buy that will still provide enough pressure and volume to run your tool.
In this case you are looking for a line that that has heavy braiding to restrict ballooning of the line while under pressure but one that does not have a thick rubber exterior.
Air Line Materials
The material used in your air line has a lot to do with dependable pressures at your tool and the life of your line.
At the very low end you will see plastic nylon line that comes in the memory coil design. This air line should not be used in high pressure applications but can be used in hobby applications such as air brushing or inflating your raft.
PVC braided line is a low end low cost air line that has a rubberized outer layer. You can probably pickup 50 feet for $25 or so and it can be used for general mechanic tools and painting.
Polyurethane is probably your best choice if you intend high duty from your air compressor. Its high durability and its resistance to Oil and abrasion will allow it to last longer in automotive and commercial applications.
Rubber line is good for high and low temperature applications. If you run a gas station and need a line for customers to get air in their tires at -23F in Minnesota then you get a rubberized hose that will not crack under pressure.
Line Pressure Rating
Because of internal manufacturing including braiding hose lines of the same size and visual appearance can not be trusted to hold the same pressure.
You may find one 1/2 inch Polyurethane line that can only withstand 200 psi and another that has a working pressure of 300 psi with a burst pressure of 1200 psi.
So, NEVER judge a hose by its outside look, weight or size. Always read the side label on the hose line before you put it into use.
Adapters
Line Adapters will come in a variety of male and female connection types.
Quick connect adapters should be used on your tool and at the end of the line it is connected to.
Although you can hard line connect a tool that you use day after day having a quick disconnect will allow you to remove the tool from the line for cleaning and repair if necessary.
Flexible adapters that you can add to your tool will provide extra freedom while using your tool.
You should make sure that the swivel will allow free motion while you use the tool.
The addition of a Swivel connector will reduce wear on your air line and should provide smooth operation.
Accessories
There are a number of additional accessories that you can attach to your air line to provide
In Line air filtering to clean air for use in painting.
Inline Oilers that add oil to your air helping make sure your tools are always well lubricated.
Inline regulators that can check the line pressure at your tool to make sure there is not a line drop between your compressor regulator and your tool.
Inline regulators are very useful by allowing you to raise your compressor output at the compressor regulator and then fine tuning your air pressure at your tool. This is great for painting because you can see your pressure drop off prior to your compressor cycling and end your work before you see problems in your paint.