Aluminum Compressed Air Piping | FAQ Answers | RapidAir

RapidAir Technical / FAQ

Below are some of the most common questions we’ve received from our customers. If your question isn’t answered in these FAQs, please give us a call. We are happy to help.

Remember, care must be taken on any installation of the RapidAir compressed air system. Read all installation instructions and watch installation videos before starting.

Technical Links:


How do I adapt to black pipe, copper, or between FastPipe and MaxLine?

All our systems can be adapted to any black pipe or copper system. All systems have an NPT pipe thread adapter fitting.

There is not a direct adapter fitting to connect FastPipe directly to MaxLine, but you can connect them with pipe thread adapters. A local hardware store will have a variety of pipe thread fittings to help you adapt to any existing threaded system.

Note: Fastpipe and maxline fittings are not interchangeable.

Adapting between systems

How do I know which size to use?

Choosing the correct diameter of pipe is based on how much flow rate will need to travel through the pipe. Flow rate is CFM (cubic feet per minute). While pressure does play a factor in flow rate, it is not important since most systems are set between 90 – 110 psi. Compressed air gets restricted over long distances and flow rate decreases the further you get from the air compressor.

The longer the distance the piping runs, the larger diameter of pipe you need. There is no benefit to changing the diameter of the pipe to a smaller diameter at the end of piping runs—doing that will decrease flow rate.

Use the Flow Rate Calculator to choose the correct diameter for your application.

Flow rate calculator

My tank outlet size is smaller than the recommended pipe diameter

The flow rate calculator says to use 3/4″ for my pipe size, but my air compressor only has a 1/2″ outlet.

The thread size of the port on your air compressor tank does not determine the pipe size for your piping system. It is calculated with the length of your piping (building size) and air compressor CFM output. Even though the port on your tank may be small, the air is only traveling through a short distance, so the restriction is minimal. Air is only restricted over a long distance with small piping.

My air compressor maximum pressure is higher than the system rated pressure

My air compressor turns off at 175 psi, but the RapidAir home garage kit has a maximum pressure of 150 psi.

All air systems should be fed at the start of the system with a regulator unit. The regulator is typically set between 90 to 110 psi. The regulator maintains constant pressure for your air tools regardless of what the compressor turn on and shut off limits are. The regulator will keep the system pressure below the rated maximum pressure of the kit. Most air tools are rated for a maximum of 120 psi, so it’s best to keep your system pressure below that limit.

How do I start my system at the air compressor?

A typical installation from the air compressor starts with a jumper hose, attached to a filter regulator unit that is mounted on the wall. The air system starts at the output side of the regulator.

Where should I put my filter regulator?

Water vapor is created when the compressed air temperature is high. Water vapor is the hardest to filter and separate out of the air stream. Cooler air turns the water to liquid, which makes it easy to filter. The further the filter is placed from the compressor, the cooler the air will be.

The most practical place for the filter regulator is close to the air compressor. This makes it convenient for mounting and plumbing the air system. To perform properly, It’s best to be at least 20 ft from the compressor. But some garages are not even 20 ft wide. While it might not perform at 100%, putting the unit next to the compressor will still work adequately.

What is a looped air system?

The best air design is a loop of piping that goes all the way around the building, starting and ending at the air compressor with a tee fitting. This allows the air to travel in two directions to any air outlet and balances the air flow.

A loop is not always practical, as some building layouts just won’t allow it. We offset this by increasing the diameter of the piping to get more flow. Single air user shops typically don’t need a loop.

Looping your air system

How do I know what size pipe thread I have?

Pipe thread DOES NOT measure like a normal threaded bolt on the outside diameter. See this attached chart for detail

Measuring pipe thread

Should I do a pressure test?

Pressure testing is essential on any installation when you will not have access to the fittings once you’re done. In wall and underground burial systems require a pressure test.

Pressure testing

Are the compressed air systems sunlight and UV resistant?

FastPipe: aluminum pipe is ok for direct sunlight, but cover the fittings.
MaxLine: tubing should be covered, fittings are ok.
Like any plastic product exposed to direct sunlight, it’s best to cover or paint the tubing to extend its working life.


Are your products OSHA Approved?

Yes, our products are OSHA rated.
OSHA does not approve any products for safety but does rely on the manufacturer for recommendations. Since we manufacture our piping for compressed air and have verified its performance, it is allowed.

OSHA has issued guidelines that PVC plastic pipe cannot be used for compressed air piping.

What is the difference between the Maxline and Duratec

Maxline is a great choice for compressed air and inert gas applications. It does not hold expensive agency ratings for food and beverage like Duratec.

What are the technical specifications for MaxLine?
What are the technical specifications for FastPipe?
What is the difference between Blue and Green?

There is no difference in materials for the different colors of tubing or piping that we offer. The reason for the different colors is so maintenance workers can know which gas is flowing inside the pipe.

Blue is used for Compressed air and Green is for inert gases.

What material are the fittings:

MaxLine Fittings are nickel plated brass. Stainless steel is also available.
FastPipe Fittings up to 2” are fiberglass injected nylon.
FastPipe Fittings 3” to 6” are die cast aluminum and stamped steel.

What is the warranty?

All products manufactured by RapidAir carry a one year warranty.

What is the max pressure rating?

MaxLine: 200 psi
FastPipe: 190 psi
RapidAir Home Garage Kit: 150 psi

What is the temperature range of your products?

MaxLine -40ﹾF to 140ﹾF
FastPipe -0ﹾF to 140ﹾF
RapidAir Home Garage Kit: -40ﹾF to 180ﹾF

What is the bend radius of the MaxLine?

1/2” Tubing: 4-6” Radius
3/4” Tubing: 6-8” Radius
1” Tubing: 10-12” Radius
2” Tubing: 36-48” Radius

What is the difference between the 1/2" RapidAir Home Garage Kit and the 1/2" MaxLine?

The RapidAir Home Garage kit uses push-to-connect style fittings, which designate their measurement on the outside of the tubing. The RapidAir tubing measures 1/2″ outside diameter x 3/8” inside diameter.

The MaxLine system uses compression fittings, which designate their measurement to the inside of the tubing. The MaxLine 1/2″ tubing measures 5/8” outside diameter x ½” inside diameter. For longer piping lengths, the MaxLine would offer more flow rate (CFM).

What style quick couplers or air chucks do I have?

There are many different styles of quick couplers that have been developed over the last 100 years. Whatever the local hardware store carried in your town is probably what your air system is now outfitted with.

See this chart for details to identify which style you have.

Quick coupler/ Air chucks

Can any of your products be buried underground or in concrete?

MaxLine is made to be direct buried in soil or concrete. Conduit covering is not required on the tubing. It’s best to wrap the fittings with our tape wrap to keep them from the elements. Sleeving up thru the concrete is a good practice.

The FastPipe aluminum air piping and the RapidAir Home Garage Kit are not suitable for underground burial.

Can the products be painted?

Yes, all of our products can be painted.

Is the MaxLine the same as PEX tubing?

No. PEX is single layer Cross Linked Polyethylene. MaxLine is multilayer High Density Polyethylene. PEX is pressure rated for water, which is a liquid and not compressible. There is no manufacturer of PEX who rates their product for compressed air. MaxLine is specifically designed for the pressure and to resist compressor oils.

Why is there moisture in my air system? What can I do about it?

The air we breathe is a combination of many gases, including oxygen and hydrogen. Oxygen likes to combine with other molecules. Through the compressor process, this creates H20 (water). Water vapor is created when the compressed air temperature is high. Water vapor is the hardest to filter and separate out of the air stream. Cooler air turns the water to liquid, which makes it easy to filter. All of our wall outlets come with moisture drains that can be used to purge the air system of condensed water.

What is the difference between a refrigerated air dryer and filter dryer/trap?

There are a few ways you can remove moisture from your air system. You’ll find that the more you spend on the dryer unit, the better it will perform.

For example, a simple $80 moisture trap/filter uses centrifugal force to remove the moisture and most water vapor will pass right thru the unit.

A $400 desiccant system works well, but uses a media similar to oil dry to catch the moisture. This media needs to be changed often. These units still allow some water vapor to pass through.

A refrigerated dryer operates like a de-humidifier and is electrically powered. It lowers the dew point of the air passing through it, which removes all the moisture and passes clean, dry air through it. A typical refrigerated dryer for a 5 hp compressor would cost $1300.

3/4” Maxline vs 3/4” Fastpipe

The 3/4 Fastpipe measures .69” on the inside of the pipe. The 3/4 Maxline measures .80” on the inside of the tubing. When comparing system flow capacities, keep in mind that the inner diameter of the 3/4 Fastpipe is smaller and in most cases a main line of 1” Fastpipe is a better choice.

1” Maxline vs 1” Fastpipe

The 1” Maxline may seem a good flexible choice when the 1” size is needed. However, it works best for underground burial, or installations where the piping can be hidden behind perlins in a steel building, or laying on trusses or above false ceilings, with minimal joints.

The 1” Maxline tubing does unroll harder than the smaller sizes and is more difficult to get straight for surface mounted systems. The compression fittings for the Maxline require more force to tighten. For on wall installations, we recommend the Fastpipe, as it is an already straight pipe, and as an easy install fitting system.

For long continuous runs with minimal fittings, Maxline is a good choice. If meticulous, straight, professional appearance is desired, always choose the Fastpipe.

1” Maxline is a great choice for direct burial, in wall or hidden installations. For in wall installation pictures of how to use the ¾” or 1” behind wall outlets see Maxline Installation photos


When will my products ship out if I order today?

We keep a huge inventory so we can ship your order out quickly. Typically, orders placed before 12:00 p.m. ship out the same day. Orders placed after noon ship out the next day.

How much is shipping?

We offer standard ship rates based on the order total for products that ship small parcel. Freight shipping costs for FastPipe and other products are based on your shipping address. We can always estimate your shipping cost for any order—all you need to do is ask.

Shipping and Returns

Can I get expedited shipping?

We would be glad to ship your order to arrive any time you need it. If you require Next Day or Saturday delivery, please call to notify us of this request and to get the extra shipping costs.

If I run out of fittings, can I buy them at a local store?

FastPipe and MaxLine do not interchange with common parts at a local store—they are specific to our systems. Some retail locations carry our products, however. To find a local retailer who carries RapidAir, MaxLine or FastPipe fittings, just give us a call.