Polyethylene (PE) pipes are commonly used for plumbing systems due to their versatility, low cost, and ease of installation. However, there are two main types of polyethylene pipes: cross linked polyethylene (PEX) and non cross linked polyethylene.
The primary difference between the two is the level of cross linking between the polymer chains. Cross linking refers to the process of chemically bonding polymer chains together to create a stronger, more durable material. Cross linked polyethylene (PEX) is created by adding a chemical agent to the polymer, which initiates a chemical reaction that links the chains together. This process creates a more durable and heat resistant material that is ideal for use in high temperature applications such as hot water systems.
On the other hand, non cross linked polyethylene is created without the addition of a cross linking agent. This material is less durable and has a lower maximum operating temperature than PEX. It is typically used in lower temperature applications such as cold water systems.
In terms of plumbing fittings, PEX fittings are designed to work specifically with cross linked polyethylene pipes, while non cross linked polyethylene fittings are designed to work with non cross linked polyethylene pipes.
The main differences between cross linked polyethylene (PEX) and non cross linked polyethylene pipes and fittings are the level of durability and heat resistance, as well as their suitability for different temperature applications.
Here are some additional differences between PEX and non cross linked polyethylene pipes and fittings:
Flexibility: PEX pipes are more flexible than non cross linked polyethylene pipes, which makes them easier to install around corners and obstacles. This flexibility also allows for expansion and contraction in response to changes in temperature, which reduces the likelihood of the pipes bursting or cracking.
Chemical resistance: PEX pipes are more resistant to chemicals than non cross linked polyethylene pipes. They can withstand exposure to common household chemicals such as bleach and drain cleaners, which can damage non cross linked polyethylene pipes over time.
Cost: PEX pipes are generally more expensive than non cross linked polyethylene pipes, but they offer superior durability and longer lifespan, which can make them a more cost effective option in the long run.
Installation: PEX pipes are typically installed using a crimping tool or a compression fitting, while non cross linked polyethylene pipes are often joined using heat fusion or mechanical fittings. The installation process for PEX is generally faster and easier than for non cross linked polyethylene pipes.
Compatibility: PEX pipes and fittings are not compatible with certain chemicals, including some types of chlorine based disinfectants. It is important to check the compatibility of the pipe and fittings with the chemicals that will be used in the plumbing system before installation.
PEX pipes and fittings offer several advantages over non cross linked polyethylene pipes and fittings, including greater durability, flexibility, and chemical resistance. However, the choice between the two will depend on the specific requirements of the plumbing system, such as the maximum operating temperature and the types of chemicals that will be used.
Maximum Operating Temperature: PEX pipes are able to withstand higher temperatures than non cross linked polyethylene pipes. The maximum operating temperature for PEX pipes is typically around 200°F, while non cross linked polyethylene pipes have a maximum operating temperature of around 140°F.
Longevity: PEX pipes have a longer lifespan than non cross linked polyethylene pipes. PEX pipes can last up to 50 years, while non cross linked polyethylene pipes typically last around 25 years.
Resistance to stress cracking: PEX pipes have a higher resistance to stress cracking than non cross linked polyethylene pipes. Stress cracking can occur when pipes are exposed to certain chemicals or when they are under stress due to changes in temperature or pressure.
UV resistance: PEX pipes are resistant to UV radiation, while non cross linked polyethylene pipes are not. This makes PEX pipes a better option for outdoor applications where the pipes will be exposed to sunlight.
Flow rate: PEX pipes have a smoother interior surface than non cross linked polyethylene pipes, which can improve flow rate and reduce pressure loss. This can be beneficial in applications where high water flow rates are necessary.
PEX pipes and fittings offer several advantages over non cross linked polyethylene pipes and fittings, including greater durability, flexibility, chemical resistance, higher maximum operating temperature, longer lifespan, resistance to stress cracking, UV resistance, and improved flow rate. However, the choice between the two will depend on the specific requirements of the plumbing system, such as the maximum operating temperature, chemicals used, and flow rate.
Oxygen permeability: PEX pipes are less permeable to oxygen than non cross linked polyethylene pipes. This can be important in certain applications, such as in radiant heating systems, where oxygen can cause corrosion and damage to the system.
Noise transmission: PEX pipes are quieter than non cross linked polyethylene pipes, as they transmit less noise through the pipes. This can be an important consideration in residential applications, where noise can be a nuisance.
Code approvals: PEX pipes and fittings are approved for use by most plumbing codes in North America, while non cross linked polyethylene pipes and fittings may not be approved in all jurisdictions. It is important to check local plumbing codes before selecting a pipe and fitting system.
Burst strength: PEX pipes have a higher burst strength than non cross linked polyethylene pipes. This means that they are less likely to burst or fail under pressure.
Availability: PEX pipes and fittings are more widely available than non cross linked polyethylene pipes and fittings. This can make it easier to find the materials needed for a plumbing project.
In conclusion, PEX pipes and fittings offer several advantages over non cross linked polyethylene pipes and fittings, including less oxygen permeability, quieter operation, wider code approvals, higher burst strength, wider availability, among others. The choice between the two will depend on the specific needs and requirements of the plumbing system, as well as the local plumbing codes and regulations.
