The plumbing and sanitary system is an essential part of every house or a building. Proper planning and designing of a plumbing system is crucial as it takes care of the basic needs of the occupants. Water is supplied to a house or a building through pipes from the storage tanks or directly from Municipal mains. Any building, be it a residential, commercial or industrial, cannot function properly without having a proper plumbing and sanitary arrangements in place.
Water can never reach to you effectively and efficiently without two essential components of a plumbing system i.e. water supply pipes and fittings. Various pipes like cast-iron pipes, plastic pipes, PEX pipes, steel pipes, copper pipes are used for household water supply.
In this article, let us particularly understand about PEX pipes used in the water supply system.
What is PEX?
PEX is an acronym for Cross Linked Polyethylene. Cross linked Polyethylene is a Polyethylene material that has changed its molecular structure by using a chemical or through a physical process wherein the polymer chains are chemically linked. Cross linking of Polyethylene into PEX for pipes results in improved properties such as high-temperature strength and performance, chemical resistance, and resistance to slow crack growth.
What is PEX Water Supply Pipe?
According to ‘Mark Johanson and Chris Peterson’[356] (Authors of Black & Decker, The Complete Guide to Plumbing), PEX water supply pipes are the flexible tubing made from the Cross-linked Polyethylene (PEX). These pipes are flexible and hence it is possible to install them in very long uninterrupted runs. These pipes can also be routed wherever it is required with fewer fittings such as elbows or bends fittings etc.
A PEX pipes comes in three colors, i.e. Red, White and Blue. As such there is no physical difference among the three, but using blue for cold water and red for hot water helps you to identify at glance as to what type of service line is running. Generally, Blue colour pipes are used for cold water supply and Red colour pipes are used for hot water supply.
Uses of PEX Pipes in Plumbing System
01. PEX (Cross Linked Polyethylene) piping can be used in a number of applications in residential construction. Moreover, it can be used for both construction and reconstruction projects of new buildings.
02. It is used for potable as well as non-potable cold and hot water distribution systems in residential and commercial buildings.
03. It is also useful for fire protection systems in residential buildings.
04. In addition to all these, it can also be used for natural gas distribution system and specialized industrial and mining applications.
Properties of PEX Pipes
01. PEX Pipe Dimensions
PEX pipes are available in the nominal sizes ranging from 16 mm to 1000 mm outer diameter.
02. Temperature and Pressure at which PEX Pipes can withstand!
American Society for Testing and Materials – ASTM F876-20[355] covers cross-linked polyethylene (PEX) tubing for different pressure at three temperatures.
- 160 psi (11.08kg/cm2) Pressure @ 73.4 0F Temperature
- 100 psi (6.93 kg/cm2) Pressure @ 180 0F Temperature
- 80 psi (5.54 kg/cm2) Pressure @ 200 0F Temperature
03. Flexibility of PEX Pipes
The flexible nature of the PEX pipe allows it to bend, twist or turn gently with ease around the obstacles and can be installed without obstruction. The direction can also be easily changed by turning the pipe with our hand. There is a predetermined bend radius of 900 facilitated for the change of direction without installing and fittings. Reducing mechanical connections leads to faster installations, less chance of leaks in the fittings, and less resistance due to pressure reduction due to fittings.
04. Noise and Water Hammer Resistance Test of PEX Pipes
As water flows through pipes, the pressure created in the system gives energy to moving water energy. This energy is known as kinetic energy. This kinetic energy increases with the speed of water; it is also influenced by the mass of water that is flowing. When the flow of water is stopped i.e.when a valve or faucet is closed, this kinetic energy has to be dissipated by the system.
The ability of a plumbing pipe to dissipate energy due to surge in water pressure is derived from the modulus of elasticity and a measure of material stiffness of the pipe.
Ultimately, this means that with rigid piping systems, pressure surges can produce noticeable banging sounds as energy is dissipated, thus causing what is known as water hammer.
The flexibility of PEX pipe allows the pipe itself to absorb energy from pressure surges and eliminate or reduce the occurrence of water hammer, consequently reducing the noise.
Noisy pipes are the warning sign of serious plumbing problems. Refer the link mentioned below to know the causes and remedial measures
05. Resistance of PEX Pipes to Freeze Damage
PEX pipes are less susceptible to the effects of cold temperatures and they can retain their flexibility even below freezing temperature. This means that even if water-filled PEX piping freezes, the elasticity of the material allows it to expand without cracking or splitting, and retain its original size after melting. This is how the flexibility of this pipe works! This is possible when PEX pipes have space to expand evenly along their lengths, when they are installed on walls or ceilings. The PEX pipes inside the slab may not expand evenly.
06. Chlorine Resistance Capacity of PEX Pipes
PEX pipes have ability to resist attack caused by chlorine and chloramines.
07. Corrosion Resistance of PEX Pipes
PEX pipes can withstand aggressive potable water conditions and do not corrode easily.
08. Ultraviolet Resistance of PEX Water Supply Pipe
The long-term performance of PEX (Cross Linked Polyethylene) pipes will be affected by UV radiation from sunlight. However, most of the PEX pipes are UV resistant to a certain extent. Nevertheless, it is recommended by the PEX pipe manufacturers to limit the exposure of the pipe to sunlight based on its UV resistance capacity. PEX pipes should not be allowed to over-expose beyond their limits.
PEX pipes should not be kept at the places which are exposed to the sun. Indirect (diffused) and reflected sunlight also has UV energy. Therefore precautions must be taken once the pipe is removed from the original container. If PEX pipes are exposed to constant sunlight after installation, cover the pipe with UV-blocking sleeves (black preferred) or approved pipe insulation.
PEX pipes have varying degrees of UV resistance, and that depends on the manufacturer. Always follow the instructions provided by the particular manufacturer.
In case you have decided to use PEX pipes, you need to look at its advantages and disadvantages.
PEX Piping Advantages
01. PEX Pipes Can Be Easily Installed
The installation of the PEX pipe is generally easier and more comfortable than a rigid pipe. It is available in long coils, which eliminates the need for joints. Its flexible nature allows it bend or turn easily, thereby minimizing the use of fittings. The lightweight of PEX Pipe makes it safe to transport and easy to handle.
02. Durability of PEX Pipes
PEX pipes are durable and do not suffer from problems associated with metal piping, like corrosion, reduced internal dimension, electrolysis, mineral build-up and water velocity. It usually expands during freezing conditions and returns to its original size when the water melts.
03. PEX Pipes Cost Effectiveness
The installation of PEX plumbing systems is faster and it also requires less labour. In addition to this, its installation cost is less compared to the rigid metallic plumbing systems. The use of PEX plumbing systems can reduce energy dissipation, thereby delivering water speedily to fixtures.
04. Energy Efficiency of PEX Piping
PEX piping reduces heat and improves thermal characteristics as compared to metallic pipes. Besides, less energy is utilized by the water heater due to the shorter delivery time for hot water with PEX parallel plumbing systems.
05. Noise Reduction Capability of PEX Pipes at the Time of Installation
If the PEX piping is properly fixed, it will make less noise. Due to its flexible nature, this pipe makes less noise. Also, because of the same flexibility, its ability to absorb pressure increases.
06. Production of PEX Pipes are Environmentally Friendly
PEX is an improvement or enhancement of high-density polyethene which is not only economical but is a highly cost-effective piping construction material. The lighter weight of PEX pipes also helps to reduce transportation costs.
PEX pipes can be reused as a passive filler material that can be incorporated into other polymers for specific applications. In addition, PEX pipe does not contain harmful Volatile organic compounds (VOCs).
PEX Pipe Disadvantages
01. PEX Pipes are not suitable for Outdoor Application
It is impossible to use PEX pipes outside. PEX pipes are affected by ultra-violate radiation of sunlight. Therefore, if the pipes are to be exposed for a longer time in the open sun, they will become unusable.
02. PEX Pipes are Costly
PEX Pipes are expensive than the regular copper pipes.After going through the advantages and disadvantages of PEX pipes, let us know their types.
Types of PEX Water Supply Pipe
There are three common types of PEX water supply pipes. i.e. PEX A, PEX B and PEX C.
01. PEX – A Pipes
PEX A pipes is the highest quality PEX pipe and the most flexible amongst all types. It is most often used with expansion fittings.
02. PEX – B Pipes
PEX B pipes can be a better choice because they are cheaper compared to copper and PEX A pipes. It is most often used with crimp-style connecters. Both PEX A and PEX B pipes are extremely durable and last longer like copper piping if not damaged or exposed to excessive UV light or chlorine.
03. PEX – C Pipes
PEX C pipes are not meant for home plumbing or domestic use. They are used for non-potable water supply applications.
Taking Everything into Account, PEX Pipes are versatile and suitable for plumbing applications because they are flexible, reliable and durable. Its pliable nature allows these pipes to bend and route wherever needed without fixtures. Also, PEX pipes require fewer fittings than rigid piping systems, thereby reducing installation time and energy losses and pressure fall.
PEX pipes do not corrode like metal plumbing. Therefore, it guarantees longevity. However, it is advisable to compare the cost of PEX pipes with the other alternatives and then make a right choice for your home plumbing system.
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