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How Much Pressure Can Pex Fittings Take? (Explained)

PEX is a popular solution for affordable and convenient piping. It is widely used for water system solutions in residential and commercial buildings. But it can be used in other systems related to piping.

As PEX is used for water transmission systems, it is common that PEX fittings need to handle quite some pressure inside the fittings. Therefore, you may ask how much pressure PEX fittings can take. Let us discuss that and some important facts related to this fact.

How much pressure can PEX fittings take?

PEX fittings can take around 800 PSI of burst pressure. This is said to be two times the requirement for the standard specification for PEX tubing. This standard specification is known as ASTM F876. But PEX fittings can have a higher-pressure range based on the type of PEX used.

PEX fittings are commonly used for water transmission systems. These transmission systems are always handling water pressure inside the fittings. Therefore, PEX fittings need to handle the pressure properly or the system may fail. 

With the average pressure rating, PEX fittings can handle that properly and easily.

Though using PEX fittings for compressed air transmission systems is not approved by the manufacturers, it is widely used in the residential area in garages for air systems. 

As garage compressed air systems require fittings that can handle around 150 – 200 PSI, PEX is the correct choice for that kind of air pressure.

There are a lot of PEX fittings in the market currently available. Among them, let us discuss some famous PEX fittings that are dominating the market and know how much pressure that they can withstand:

Uponor PEX fittings:

Uponor PEX fittings can take around 750 PSI pressure. It is commonly known as a PEX-A type fitting which is widely used for water supply systems.

Viega PEX fittings:

Viega PEX fittings are another known PEX-A type PEX fittings. It is commonly used for water and air transmission systems for better pressure withstanding. It can hold around 800 PSI of pressure.

Sharkbite PEX fittings:

Sharkbite PEX fittings are widely known as PEX-B type PEX fittings for their strong and rigid body. It can hold around 1000 PSI pressure which makes it one of the strongest pipes and highest pressure withstand ranges.

What is the pressure rating for PEX fittings?

The pressure rating for PEX fittings according to the ASTM F876 is around 480 PSI. This rating varies based on the size and quality of PEX fittings used in the residential and construction buildings. There are more factors that make the pressure rating vary.

The pressure rating for PEX fittings also varies due to environmental reasons such as temperature, UV rays and many more. Thus, it is recommended by the manufacturer that the user must use the PEX fittings inside the building where there is no direct contact of light.

Depending on the size, the pressure rating for PEX fittings varies. Here is the pressure rating for a few famous PEX fittings available in the market and popular among users:

1/2 PEX fittings:

For 1/2 PEX fittings, the minimum pressure rating of it is around 480 PSI. This rating is based on the ASTM F876 law and at a certain temperature of around 73 degrees Fahrenheit.

3/4 PEX fittings:

A 3/4 PEX fitting can withstand pressures around 475 PSI at around 73 degrees Fahrenheit temperature. This range is known as the minimum hydrostatic burst pressure for a PEX pipe like this.

1 PEX fittings:

1 PEX fittings are one of the highest sizes of PEX fittings available in the market that is widely used for residential and commercial purposes. This has a pressure rating of around 470 PSI.

How to pressure test PEX?

There are many ways that you can do a pressure test of PEX. Before doing it you must purchase some necessary tools like a pressure gauge, measuring container and stopwatch. Using these things, you can easily do the pressure test of PEX.

Before doing the test, keep in mind that you should do the pressure test of PEX for around a full 1 minute. Now let us discuss the 3 simple steps to do this test:

Turn off all water sources of the test area:

The first step to do is to turn off all water sources in the test area. If any water is leaking in the system, it should be fixed before the test is performed or the results of the test will be inconsistent.

Connect the pressure gauge:

After confirming that none of your water sources are leaking and properly turned off, you need to connect the pressure gauge with a point. The point can be a tap or any other thing. 

But attaching the gauge with the source you want to test will be ideal and after doing that turn on the tap by attaching a hosepipe to it.

Observe the static water pressure of the connected source:

When you turn on the tap or source, you should turn it on at full force. The needle of the gauge should move and the reading should show pressure ranges around 35 – 60 PSI. The standard pressure range of a PEX is around 40 – 60 PSI.

Can PEX hold compressed air?

Although manufacturers do not recommend using PEX to hold compressed air, it can handle it without any issue. PEX fittings are made for water transmission systems. But it is used by people for compressed air use. 

They use it to run compressed air from their garage to fix their flat tires and for many other reasons.

PEX can easily handle the pressure of compressed air. Usually, for residential usage, compressors of garages only provide pressure of around 200 – 250 PSI. Therefore, this is within the range of PEX and can be held by it.

Can you use PEX for the pressure relief valve?

Yes, you can use PEX for the pressure relief valve. Though it is approved by various building codes and regulations, it is rare to see that PEX is used as the pressure release valve. 

Pressure release valves are basically valves that help reduce the excess pressure that has built inside a line.

According to International Residential Code (IRC), any pipe can be used for a pressure release valve. But the user has to keep in mind that while using PEX as a pressure release valve, it should be one size larger than the pressure release valve outlet. 

The valve and PEX should be secured properly in place in order to maintain the IRC laws.

Can PEX fittings be used underground?

Yes, PEX fittings can be used underground. Although PEX fittings are flexible and may look like they may break in external pressure, many home builders and contractors use PEX fittings underground by maintaining certain regulations.

PEX fittings underground are often buried in the ground or inserted inside a slab. The reason behind this is that the fittings will not get frozen when the temperature of the environment drops. Sometimes, the PEX fittings are insulted for the same reason.

If the PEX gets frozen, then it may burst due to the standing water inside the fitting. Thus, when using PEX fitting underground, insulating it properly is a must.

Can PEX water lines burst?

Yes, PEX water lines can burst. Like all other pipes, PEX has a rated range that it can handle without any issue. But when any of the factors exceeds the range, the PEX used at your building will burst.

Even the brass PEX fittings have a range that it can handle and starts to crack or decay when it reaches that rating of that factor. 

The maximum temperature that it can take is around 200 degrees Fahrenheit at which it holds around 240 PSI and the maximum pressure it can take is 770 PSI at around 73 degrees Fahrenheit.

It may burst due to various reasons. Let us discuss the most common reasons when this problem occurs:

Freezing temperatures:

If the temperature of the environment is below freezing, then the pipe may burst due to the standing water in them if you do not use them for some time.

High water pressure:

PEX is rated for 200 – 250 PSI for water system transmission. But if the system has pressure over this range, then it may cause the system to burst.

Direct contact with UV light:

Keeping a PEX pipe in the open exposes it to the UV light of the sun. UV light may cause the pipe to create cracks. These cracks may result in massive failures in the system which may end up bursting the PEX.

Final thoughts

PEX fittings can take around 480 PSI of pressure on average. Though it has a burst pressure range of 850 PSI which is double the accordance of ASTM F876, it is better to maintain the pressure ranges provided by the manufacturer. They test and then provide the safe pressure range of that PEX fitting.