EXPANSION AND CONTRACTION OF uPVC PIPE :
uPVC pipes, like other piping materials, undergo length changes as a result of temperature variations above and below the installation temperature. They or iron pipe. The extent of the expansion - expansion of piping material. The length of pipe between directional changes, and the temperature differential.
The coefficient of thermal expansion (Y) for uPVC is 3.1 × 10-5in./in./Fº.
There are several ways to compensate for expansion and contraction. The most common methods are :
1. Expansion loops which consist of pipe and 90º elbows
2. Piston type expansion joints*
3. Flexible bends*
4. Bellows and rubber expansion joints*
* The manufacturers of these devices should be contacted to determine the suitability of their products for the specific application.
Expansion loops are a simple and convenient way to compensate for expansion and contraction when there is suffcient space for the loop in the piping system. A typical expansion loop design is shown below.
The length of leg "R" can be determined by using the following formula to ensure that iis is long enough to absorb the expansion and contraction movement without damage. The length of leg"A" should be 1/2 the length of leg"R"
The amount of expansion or contraction can be calculated using the following formula :
L = Y (T1 - T2) × L
L = Dimensional change due to thermal expansion or contraction (in.)
Y = Expansion coefficient (in./in./ºF)
(T1 - T2) = Temperature differential between the installation temperature and the maximum of minimum system temperature, whichever privides the greatest differential (ºF).
L = Length of pipe run between changes in direction (ft)
R = 1.44
R = Expansion loop leg length (ft)
D = Nominal outside diameter of pipe (in). (See table below.)
L = Dimensional change due to thermal expansion or contraction (in.)
When installing the expansion loop. no rigid or restraining supports should be placed within the leg lengths of the loop. The loop should be installed as closely as possible to the mid-point between anchors. Piping support guides should restrict lateral movement and direct axial movement into the loop. lastly, the pipe and fittings should be solvent cemented together, rather than using threaded connections.
Compensation for expansion and contraction in underground application is normally achieved by snaking the pipe in the trench. Proper trenching and burial procedures must be followed to protect the piping system.
The table below shows recommended offsets and loop lengths for piping up to 2½" nominal size.
SUPPORT AND SPACING FOR uPVC PIPE :
Adequate supports for any piping system is a matter of great importance. in practice, support spacings are a function of pipe size operating temperatures, the location of heavy valves of fittings and the mechanical properties of the pipe material,
To ensure the satisfactory operation of a ASTRAL Aquarius uPVC piping system, the location and type of hangers should be carefully considered. Hangers should not compress, distort, cut or abrade the piping.
All piping should be supported with an approved hanger at intervals sufficiently close to maintain correct pipe alignment and to prevent sagging or geade reversal. Pipe alignment and to prevent sagging or branch ends and at all changes of direction. Support trap arms as close as possible to the trap. In keeping with good plumbing practices support and brace all closet bends and fasten closet flanges.
(1) Concentrated loads should be supported directly so as to eliminate high stress concentrations. Should this be impractical then the pipe must be supported immediately adjacent to the load.
(2) In systems where large fluctuations in temperature occur, allowances must be made for expansion and contraction of the piping system. Since changes in direction in the system are usually sufficient to allow for expansion and contraction hangers must be placed so as not to restrict this movement.
(3) Since plastic pipe expands or contracts approximately five times greater than those of steel, hangers should not restrict this movement.
(4) Hangers should provide as much bearing surface as possible. To prevent damage to the pipe, file smooth any sharp edges of burrs on the hangers or supports.
(5) Support spacing for horizontal piping systems is determined by the maximum operating temperature the system will encounter. The piping should be supported on uniform centers with supports that do not restrict the axial movement.
(6) For vertical lines, it is recommended that an engineer should design the vertical supports engineer should design the vertical load involved.
Strong and Light Weight :
PVC's abrasion resistance, light weight, good mechanical strength and toughness are key technical advantages for its use in building and construction applications.
Easy to Install :
PVC can be cut, shaped, welded and joined easily in a variety of styles.
Fire Resistant :
PVC is inherently difficult to ignite and stops burning once the source of heat is removed. Compared to its common plastic alternatives PVC performs better in terms of lower combustibility, flammability, flame propagation and heat release. Newly developed advantages in terms of lower acid emissions, smoke generation and enhanced fire resistance.
PVC is resistant to weathering, chemical rotting, corrosion, shock and abrasion, it is therefore the preferred choice for a range of customers for many different long-life and outdoor products. In fact, medium and long term applications account for some 85 percent of PVC production in the building and construction sector. PVC building products are lighter than those made of concrete, iron or steel. This requires less fuel and generates fewer emissions during transportation. They are also durable, so frequent replacement is not required.
Cost - Effective :
PVC has been a popular material for construction applications for decades due to its physical and technical properties which provide excellent cost-performance advantages. As a material it is very competitive in terms of price, this value is also enhanced by the properties such as its durability, lifespan and low maintenance.
Environmental Impact :
In lifecycle analyses and independent studies, PVC's environmental impact has been found to be favourable when compared with other manufactured materials used for construction. It is comparatively low in its energy and resource use during production, as well as in conversion to finished products.
Good Iinsulator :
PVC does not conduct electricity Astral Aquarius is a non-conductor of electricity so it makes the plumbing system safe when working with electrical tools or equipments SAFE MATERIAL Astral Aquarius is non-toxic Astral Aquarius is lead free which makes it a safe material for potable water. It is also the world's most researched and thoroughly tested plastic PVC meets all international standards for safety and health for both the products and applications for which it is used.
The physical properties of PVC allow designers a high degree of freedom when designing new products and developing solutions where PVC acts as a replacement or refurbishment material.