Pip's Island » What Size Pipe For Air Compressor? (Precise & Calculation)

What Size Pipe For Air Compressor? (Precise & Calculation)

Are you thinking about using an air compressor to power some of your tools? They can be useful machines, for example in your garage. If you are using an air compressor, it is important to know what size piping you need for your compressed air system because using the correct size pipe will improve the efficiency of your system.

You can save money using correctly sized compressed air piping because it will ensure that you have the right PSI to run the tools and machines you need. We have written this guide to help you determine what size pipe you need for your air compressor.

What is an Air Compressor?

Let’s start with the basics and look at what an air compressor is. An air compressor is a pneumatic device, which generates and uses compressed air. The system uses an electric motor or a diesel engine to convert power into potential energy stored in pressurized air.

Air compressors are often classified according to the pressure they can deliver. Low-pressure air compressors have a compressor discharge pressure of 150 PSI or less. Medium-pressure compressors have a discharge between 151 and 1,000 PSI, and high-pressure air compressors have a discharge higher than 1,000 PSI.

How do Air Compressors work?

Using an electric motor or a diesel engine, the compressor will force more and more air into a storage tank and increase the pressure. When the upper limit of the tank is reached, the air compressor will shut off.

The tank will hold the compressed air until it is needed. You can use the energy in the compressed air using kinetic energy created as the air is released and the tank depressurizes. The pressurized air from the tank can power tools such as sanders, nailers, paint sprayers, and impact wrenches.

Types of Air Compressors

Types of Air Compressors

There are different types of air compressors and you need to know what type of air compressor you have to choose the correct pipe for it. The four most common air compressor types are:

Axial

Axial air compressors are usually found in high-speed engines on planes and ships. They are more expensive than other air compressors but are highly efficient. They are a type of dynamic compressor.

Centrifugal

Centrifugal air compressor works by slowing and cooling incoming air. They are capable of producing a high amount of energy because of their multi-phase compression process. Because they can produce a high amount of energy, they are often used in large construction sites and steel and chemical manufacturing plants.

Reciprocating

Reciprocating air compressors are displacement compressors that are typically found at smaller work sites. They work via a piston inside the cylinder and are not designed for continuous use. Reciprocating Air Compressors are well suited for use at home and in small-scale projects.

Rotary Screw

The rotary screw compressor is another type of displacement compressor and one of the easiest compressors to take care of because they are equipped with an internal cooling system. They are designed for continuous use and are best for large-scale jobs in an industrial setting.

Why is Having The Right Size Piping Important?

Why is Having The Right Size Piping Important?

When you are choosing the right pipe for your air compressor, there are two main points you need to consider:

  • How far does your air need to go?
  • How much air do you want to move?

When compressed air is moved through the pipes, pressure loss occurs as it travels because of friction in the pipes. This will lead to the pressure dropping. If your pipe is too small for your system, there will be more friction, and therefore, more loss of pressure.

If your piping is too small, you may need to raise the PSI system to compensate for the loss of pressure, or your machines and tools will not function properly. This will significantly increase the energy costs for your compressor.

Unlike too small pipes, too big pipes will not negatively affect your system’s performance. However, they will cost you more to install as you require more materials. They are also not the most efficient way to store air. You will be better off investing in a larger air receiver tank than larger pipes.

PSI

When choosing the pipe for your system, you need to understand the minimum required operating pressure. This is measured in pounds per square inch, PSI for short. Most industrial tools need between 90 and 100 PSI to function correctly.

You can use PSI to determine the pressure drop for your system. How you do this is by comparing PSI at the air compressor and the outlet. If the drop is over three PSI, and you cannot detect a significant leak, this may mean that your piping is too small.

CFM

Your required pipe size is related to the maximum airflow that goes through your system. This airflow is measured in cubic feet of air per minute (CFM). You need larger pipes to cater for greater CFM and to avoid pressure drop.

How Can You Minimize Pressure Drop in Your System?

Choosing the correct pipe size is a key factor in reducing pressure drop. However, the material of your pipes can also make a significant difference. Using corrosion-resistant and smooth materials such as aluminum pipes can reduce the pressure drop and help to maintain a suitable air velocity.

Other types of pipe that can help reduce the pressure drop include PVC pipe, stainless steel pipe, and copper pipe. Pipe length and straight pipes with a reduced number of bends and connections can also help to maintain an air velocity of 20 to 30 feet per second.

How to Calculate the Size of the Air Compressor Pipe You Need?

How to Calculate the Size of the Air Compressor Pipe You Need?

How do you work out the correct pipe diameter for your system? There are different ways you can determine the accurate compressed air piping size for you. For example, there is a formula you can use, which we will discuss shortly. Alternatively, you can use tables that show CFM ratings of compressed air based on PSI and distance.

When you are calculating the size of the pipe, you need to consider your current and future needs. If your calculation is at the upper range of the CFM ratings, consider choosing the next size up.

Other important factors to consider are the length of your system and the number of connections and turns in your piping system. The length of pipes and the connections and turns will add friction and lead to more pressure loss. Take this into account when calculating the compressed air piping size for your compressed air distribution system.

The Formula

If you would like to use the formula to work out the size of your air compressor system pipes, it is A= 144*Q*Pa / V*60*(Pd+Pa).

In the formula, the letters and letter combinations represent the following:

  • A is the area of the cross-section of the pipe bore in square inches (3.14 x diameter squared/4).
  • Q is the flow rate (SCFM).
  • Pa stands for the current absolute pressure in pounds per square inch.
  • V is the velocity of the design pipe in feet per second, and this should not exceed 40 feet per second.
  • Pd is the compression gauge pressure, excluding the absolute pressure at the time.

Using The Sizing Chart for Compressed Air Pipes

Luckily, it is not necessary to use the formula to work out the size of pipes you need. You can also use a sizing chart, which many find much easier than the formula. However, there are certain procedures you need to follow, which are:

  • Calculate the maximum CFM for your system. You can use the link we shared above.
  • Make a piping diagram with all the pipe diameters, connections, regulators, and bends.
  • Measure all the short paths and add them together.
  • For each outlet, joint, or curve, add more similar dimensions.
  • Add similar sizes of connections and lengths to calculate the overall pipe size.

The charts come in different shapes and sizes. Here we have included two examples for you. One from About Air Compressors and the other from Infinity Pipe Systems. You may also find this video from Sandblasting Machines where they discuss air compressors useful.

Conclusion

A successful installation and use of an air compression system require the use of correct size pipes. When choosing the right size pipes, you need to consider:

  • the type of air compressor
  • the PSI
  • the maximum CFM of your system
  • the length of your piping
  • the bends and connections of your piping and air hose.

Choosing the correct size pipe will reduce pressure loss and make the system more efficient, which will save you money.

Should you would like to ask about what size pipe is best for your air compressor, you can write the questions in the comments section.

Leave a Comment