The main difference between UPVC and CPVC is that UPVC is unplasticized while CPVC contains plasticizers and is also chlorinated. As a result, UPVC is quite rigid while CPVC is flexible and can withstand high temperatures.
uPVC (Unplasticized Polyvinyl Chloride)
- Composition: uPVC pipes are made from rigid PVC without the use of plasticizers, which makes them stiffer and more stable.
- Temperature Range: uPVC pipes are suitable for cold and hot water applications, with a temperature range typically up to 140°F (60°C). They can handle hot water at lower pressures.
- Chemical Resistance: uPVC pipes are highly resistant to chemicals, acids, and bases, making them suitable for a wide range of applications.
- UV Resistance: uPVC pipes are highly resistant to ultraviolet (UV) radiation and are suitable for outdoor and exposed installations without degradation.
- Applications: uPVC pipes are commonly used for potable water supply, drainage, sewage systems, irrigation, and outdoor plumbing.
CPVC (Chlorinated Polyvinyl Chloride)
- Composition: CPVC pipes are made by chlorinating PVC resin, which increases their ability to withstand higher temperatures.
- Temperature Range: CPVC pipes are designed to handle higher temperature ranges compared to uPVC pipes. They are suitable for both cold and hot water applications, with a temperature range typically up to 200°F (93°C).
- Chemical Resistance: CPVC pipes exhibit excellent chemical resistance and can withstand a broader range of chemicals compared to uPVC.
- UV Resistance: CPVC pipes are not as UV-resistant as uPVC pipes and are best suited for indoor and buried applications to avoid exposure to sunlight.
- Applications: CPVC pipes are commonly used for hot water distribution, industrial processes, chemical transport, and applications where higher temperature resistance is required.
Key Differences
- uPVC pipes are more rigid and stable, while CPVC pipes have improved temperature resistance and flexibility.
- CPVC pipes can handle higher temperatures (up to 200°F or 93°C) compared to uPVC pipes (up to 140°F or 60°C).
- CPVC is better suited for industrial and chemical applications due to its enhanced chemical resistance.
- uPVC pipes are preferred for outdoor and exposed installations due to their UV resistance.
- Both types of pipes require solvent cement for joints, but the cement used for CPVC is formulated specifically for CPVC pipes.
UPVC vs CPVC
| UPVC | CPVC |
|---|---|
| Unplasticized polyvinyl chloride | Chlorinated polyvinyl chloride |
| Rigid | Flexible |
| Not certified to supply drinking water | certified to supply drinking water |
| Can withstand temperature of up to140 degrees Fahrenheit | Can withstand temperature of up to 200 degrees Fahrenheit |
| Can't transport hot liquids | Can transport hot liquids |
| Contains no plasticizers | Contains plasticizers |
Let us now look at the properties and characteristics of both UPVC and CPVC in more detail.
1. Chemical Composition
UPVC simply means unplasticized polyvinyl chloride while CPVC stands for chlorinated polyvinyl chloride. CPVC has therefore undergone a chlorination process and also contains plasticizers (BPA and phthalates).
CPVC is produced by the chlorination of a PVC polymer through a free radical chlorination. The reaction is started by UV energy which decomposes chlorine gas into radicals.
In the reaction, the chlorine radicals react with PVC whereby hydrogen atoms are replaced by chlorine atoms. Usually, the chlorine content in PVC is usually around 57% but after chlorination it increases to around 69%.
2. Flexibility
Naturally, PVC is quite a rigid material. That makes it undesirable for certain applications like when you want to bend it or snake it through a curve.
That is the main reason plasticizers are added to PVC material. Plasticized PVC like CPVC pipes are quite flexible and can therefore be bent. On the other hand, UPVC is rigid and cannot be bent, lest it cracks.
Due to its strength and resistance to bending, UPVC is widely used as an alternative for wood in construction especially in the manufacture of window and door frames.
UPVC door and window frames can be made to look exactly like wood and do not change shape despite the weather conditions, although at very high temperatures they can be deformed/reshaped.
CPVC pipes are a great choice for residential plumbing especially where flexibility is needed. Drain lines don’t always follow a straight line and sometimes may need to be installed around a curve and that is where CPVC’s flexibility comes in.
3. Temperature Limits
The main reason CPVC goes through the chlorination process is to increase its ability to handle high temperatures. CPVC pipes are the only plastic pipes allowed to be used in the supply of hot water.
As I mentioned earlier, UPVC will only handle temperature of up to 1400 F before it starts to soften. Thanks to the chlorination process, CPVC can withstand temperature of up to 2000 F.
In most homes, most folks set their water heater thermostats at between 120 and 140 degrees Fahrenheit. Using a pipe with the exact temperature limit as that of the water is unsafe and that is why UPVC pipes are not allowed for use in hot water transportation.
Although unrelated to temperature, another thing that makes CPVC pipes better for use in supply of water is that they are available in both nominal pipe size and copper tube size.
You can therefore replace a copper water supply system using CPVC. You just need to specify which connection you need when buying the pipes.
4. Water Safety
When it comes to safety, especially of drinking water, plastic pipes are less preferred by some folks over other materials like copper. The question that most people would want answered is whether these pipes are actually safe for supply of potable/drinking water.
Plasticized PVC pipes are banned in some countries due to the plasticizers added especially BPA. CPVC pipes (plasticized) are however legal in the United States and are actually certified for supply of drinking water.
BPA (Bisphenol A) is also used in food and drink packaging and containers. According to United States Food and Drug Administration (FDA), the current BPA levels in the packaging, (same as those used in CPVC) are safe.
Despite the lack of plasticizers, UPVC is not certified to be used for drinking water. The manufacture of UPVC pipes is not controlled and hence overload of filler materials is not uncommon.
Apart from that, lead is used as a stabilizer by some UPVC pipe manufactures. Lead is one of the most toxic metals and will leach into the water and is especially harmful to pregnant women and young kids.
CPVC pipes however are certified for supply of drinking water since they only contain tin stabilizers, which is not harmful. The BPA levels are also quite low and are therefore considered safe.
5. Corrosion Resistance
Unlike cast-iron and other type of metal pipes, both UPVC and CPVC are corrosion-resistant and will therefore not corrode.
One advantage of CPVC is that it will not be affected by chlorine present in the water. The high chlorine content also prevents the growth of bacteria inside pipes, which is not the case with UPVC.
UPVC pipes however have a very low friction coefficient. The inside of UPVC pipes is way smoother compared to CPVC pipes meaning fluids flow through them with limited resistance. This also prevents the growth of sludge/scales inside the pipes.
6. Pressure Rating
Unknown to most people, the pressure rating of a pipe reduces with increase in temperature. At 730F, both UPVC and CPVC have the same pressure rating. However, as the temperature increases, CPVC pipes maintain their pressure rating better than UPVC pipes.
For example, at 1300F, UPVC will have a de-rating factor of 0.31 compared to CPVC’s 0.57. According to this PVC pipes pressure chart, a 10-inch schedule 80 pipe has a pressure rating of 230 psi at the normal temperatures.
When the temperature is raised to 1300F, UPVC allowable pressure limit will be (0.31 x 230 = 71.3 psi) while that of CPVC will be (230 x 0.57 = 131.1 psi).
Conclusion
UPVC is basically unplasticized PVC which is used to manufacture rigid pipes for heavy-duty plumbing and also to make door and window frames. On the other hand, CPVC is both chlorinated and plasticized PVC that is used to make flexible pipes for drainage, irrigation as well as supply of cold and hot water.