CPVC or PVC: Which Is Better?

Polyvinyl chloride (PVC) is a versatile and familiar thermoplastic material mostly used as a fitting and piping material in commercial and residential plumbing applications. CPVC (chlorinated polyvinyl chloride) is another material that is in the same family as PVC. Both are widely used, but which is better?

CPVC is better than PVC when it comes to pressure and temperature resistance. Even though CPVC is similar to PVC in both available product types and names, it experiences superior resistance to pressure and heat that enables its use in more demanding industrial applications. 

The differences in pressure and heat resistance originate from the molecular makeup of the materials. Here, we explore the differences between PVC and CPVC to determine which is better. 

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Should You Use PVC or CPVC?

You should use CPVC if you’re looking for a material with good chemical, pressure, and heat resistance. However, the type of material that you should use depends on the situation you want to address. 

You should understand that most of the critical characteristics of PVC and CPVC are consistent between the two materials. The molecular differences of CPVC, mainly regarding pressure and temperature resistance, make it superior to PVC. 

Let’s look at the use cases in different situations:

Chemical Resistance

Thermoplastics have been growing in popularity over the last ten years, mainly as alternatives to traditional metals. For instance, the PVC market, whose value stood at $57 billion in 2015, is projected to reach $79 by the end of 2021. 

Unlike metals that can be affected by scaling, pitting, and corrosion, CPVC and PVC are resistant to bases, salts, most acids, and aliphatic hydrocarbons. This has proven to extend the lifespan of these materials for decades or years longer. 

Chemical resistance is, therefore, a clear advantage of both PVC and CPVC. However, the difference in chlorine content means that both CPVC and PVC have unique functions, with each possessing a niche advantage. 

If you consider the high sulfuric acid concentration, and both materials are expertly manufactured, PVC is inferior to CPVC. 

However, ammonia is very reactive when in contact with chlorine. Since CPVC has a high ammonia content, PVC functions better in cases where there is ammonia. 

Before you decide to use CPVC, you can consult a chemical compatibility chart. You can also ask for assistance from an expert. 

Temperature Resistance

The glass transition temperature (Tg) increases with a rise in the content of chlorine in CPVC. The transition temperature is when a polymer changes from glass and hard material to a rubbery and soft substance leading to the loss of its structural integrity. 

CPVC has a superior temperature resistance compared to PVC. For instance, the PVC has a maximum service temperature of 140°F (60°C). CPVC, on the other hand, has a maximum service temperature of 200°F (93.3°C). However, you should always confirm the operating capabilities of each material with the manufacturer. 

CPVC can function well over the maximum service temperature of PVC. It also has an increased temperature resistance that allows it to function effectively at temperatures within the working range of PVC. 

For instance, CPVC still offers better tensile strength and impact strength than PVC at temperatures below 140°F (60°C). 

Pressure Resistance

PVC and CPVC are designed for the same pressure at temperatures of 73°F (22.8°C). However, with an increase in temperature, CPVC will maintain temperature better than PVC. 

For instance, let’s look at the pressure rating for 10 in. Arrange 80 piping at a temperature of 130°F (54.4°C) for both PVC and CPVC. Note that at the temperature of 73°F (22.8°C), each material is rated at 230 psi. 

  • At temperatures of 130°F (54.4°C), PVC boasts a derating factor of 0.31. Its pressure is therefore rated at 71.3 psi (230 psi x 0.31 = 71.3 psi). 
  • At temperatures of 130°F (54.4°C), CPVC boasts a derating factor of 0.57. Its pressure is therefore rated at 131.1 psi (230 psi x 0.57 = 131.1 psi). 

Even though your PVC material can function well at a temperature of 130°F (54.4°C), it’ll withstand less pressure at increased temperatures.

Fire Performance

When it comes to fire resistance, all thermoplastics such as polyethylene and polypropylene often have a negative reputation. However, not all thermoplastics are susceptible to melting and burning.

Industrial CPVC is engineered to limit smoke production and flammability. Some tests will measure your material’s:

  • Flash Ignition Temperature: This is the smallest temperature at which an external flame can ignite any combustible gas. The flashing ignition temperature for PVC is 750°F (399°C) while that for CPVC stands at 900°F (482°C).
  • Limiting Oxygen Index (LOI): This is the percentage of oxygen required to sustain a flame in the surrounding atmosphere. The LOI for Corzan CPVC stands at 60 while that of PVC is 45. For your reference, the atmosphere has 21% oxygen. 

Can You Use PVC Instead of CPVC?

It is safe to employ PVC in certain situations in place of CPVC because they have several similarities in the application. Here are some of those:

PVCCPVC
Resistant to alkali, acid, and inorganic chemicals

Easy to install

Cheaper than copper

Maintains water temperature

Decreases the formation of condensation

Prevents oxidation

For instance, both materials are safe in portable water transport such as bathing, drinking, and cooking water. However, you should only employ either on plumbing that has an ANSI/NSF 61 certification. 

Both PVC and CPVC are resistant to chemicals and offer significant resistance to degradation from alkali, acid, and most inorganic chemicals. However, in both materials, you must employ an underground installation and use UV stabilizers to limit deterioration from the sun. 

PVC and CPVC are easier to install, quieter, and cheaper than iron and copper pipes, especially for plumbing applications. Since they are thermoplastics, they contain inherent insulation that decreases the formation of condensation on lines. This enables them to maintain hot and cold water temperatures better compared to copper pipes

The two materials are available in the same end shape options and lengths. Since their chemical composition has chlorine, a halogen, they have an innate fire retardant and stable structure. 

The stability of the material prevents oxidation, thus leading to both CPVC and PVC experiencing a long performance life. You can identify each material either by reading the manufacturer’s printing on the side of the pipe or checking the pipe color. 

Can You Glue PVC and CPVC Together?

There are certain cases where you can join PVC and CPVC materials together. However, you can’t join them using a coupling.

In such a scenario, follow the steps below:

  1. Prepare your pieces of the CPVC to PVC connection. Here, you must prime the first 2-inches of your exterior CPVC and PVC surfaces using a CPVC primer. You can then proceed to prime the interior of the PVC to the CPVC adapter. The priming brush is normally attached to the lid of the primer can.
  1. You can proceed to apply some light coating of CPVC glue on the primed area of the pipe. Do the same to the side of the PVC-to-CPVC adapter. 
  1. Slide the glued side of your adapter onto the CPVC pipe’s glued end. You can then hold the adapter on that end for about 30 seconds to bond effectively to the pieces. 
  1. You can apply glue to the PVC end of your PVC-to_CPVC adapter. Do the same to the primed end of your PVC pipe.  
  1. Join the glued open adapter side to the glued PVC pipe end and hold them in place for about 30 seconds to finish the joining process. 

Why Is CPVC Plumbing Recommended Over PVC Piping In Homes?

I recommend employing CPVC in your applications compared to PVC because of the chemical composition of CPVC that makes it perfect for almost all kinds of applications.

And, it’s not by chance that many people use CPVC compared to PVC. Let us look at the reason why CPVC is recommended over PVC:

1. CPVC has a longer lifespan

As we have seen above, both PVC and CPVC are resistant to bases, salts, most acids, and aliphatic hydrocarbons. This means that the materials will experience a longer lifespan compared to other common materials. 

However, CPVC has higher chemical resistance properties compared to PVC. For this reason, we recommend you employ CPVC for highly reactive tasks. 

2. CPVC has a higher maximum service temperature

CPVC also boasts a higher resistance to temperature compared to PVC. The glass transition temperature (Tg) increases with a rise in the content of chlorine in CPVC. As highlighted above, it is the temperature point where a polymer changes from glass and hard material to a rubbery and soft substance that leads it to lose its structural integrity.

For instance, while PVC has a maximum service temperature of 140°F (60°C), CPVC boasts an even higher maximum service temperature of 200°F (93.3°C). This means that CPVC offers a better temperature resistance. 

3. CPVC offers higher pressure resistance

Another reason why CPVC is recommended in homes is that it offers a higher pressure resistance compared to PVC. While PVC records a PSi of 71.3 psi at the temperature of 130°F (54.4°C), CPVC can withstand a pressure of 131.1 psi at the same temperatures. This means that you can employ CPVC in higher pressure plumbing situations. 

4. CPVC is less susceptible to melting or burning

Apart from offering higher resistance to pressure, chemicals, and temperature, CPVC also has a high resistance to fire compared to PVC. In most cases, it isn’t susceptible to melting or burning. 

Industrial CPVC is designed to restrict smoke production and flammability. While PVC boasts a flashing ignition temperature of 750°F (399°C), CPVC’s value stands at 900°F (482°C).

5. CPVC has a higher limiting oxygen index

CPVC also has a higher limiting oxygen index value of 60, which is higher than the limiting oxygen index of PVC, which stands at 45.

Even though CPVC has better resistance properties to fire, temperature, pressure, and chemicals, you should never avoid using PVC when you see it fit.  

Uses for Both PVC and CPVC Piping

You can use CPVC for water lines and many other purposes. CPVC materials are ideal for hot water applications of up to 200 degrees Fahrenheit. However, you can still use the material in unheated systems such as drainage and vent systems. CPVC is common in both cold and hot potable water systems. 

Are you wondering where else you can effectively apply CPVC or PVC materials? If yes, we got you covered with a solution.

PVC Uses

PVC is a low-cost and reliable material that you can easily install without requiring expensive skilled labor. Uses include: 

Water: PVC exhibits relatively low corrosion resistance, which makes it ideal for low-pressure and temperature plumbing applications. They include:

  • Drainage
  • Sanitary sewers
  • Drinking water
  • Storm sewers

Housing: You can fabricate PVC materials to replace other materials. This includes using them as a sturdy and lightweight substitute for wood. The material can be finished and painted to offer the appearance of traditional materials.

  • Flooring
  • Vinyl siding
  • Window sills
  • Window frames
  • Cabinet finishes

Signage: since PVC is relatively durable, easily painted, and economical, its sheets are commonly employed in signage. 

Insulation of electric cables: Plasticizers make PVC more flexible and softer for application as cable insulators. PVC is also inexpensive and resistant to fire. 

CPVC Uses

As we have seen above, CPVC builds on the strength of PVC. This means that it can be employed in many applications compared to PVC. 

CPVC is the reliable option for situations that require chemical resistance and demanding pressure and temperature conditions. The uses of CPVC include: 

Industrial Applications: CPVC offers a long-lasting and problem-free solution for harsh industrial environments. You can employ the material in the industries below:

  • Chemical processing: Transports chemicals under pressure, at high temperatures, and without corrosion concerns. 
  • Chlor alkali: Transports chemicals through corrosive environments without any corrosion-related challenges.
  • Mineral processing: CPVC can withstand the demands of raw and precious material processing operations.
  • Power generation: It can withstand the corrosive chemicals and high pressures commonly used by power plants. 
  • Semiconductor: Has smoke and flame-resistance properties that enhance safety, prevents contamination in cleanrooms, and increases efficiency.
  • Wastewater treatment: It ends corrosion even in cases where there is the transportation of disinfection chemicals. 

Commercial and Residential Plumbing: CPVC offers a more safe and efficient environment to applications that need more pressure and temperature reliability. Some of the uses here include: 

  • Hospitality: low-rise office and restaurant buildings.
  • Retail: Shopping malls and mid-rise office buildings.
  • Education: This includes colleges, universities, and k-12 schools.
  • Healthcare: Medical complexes, medical clinics, and hospitals. 
  • Multi-family: Structures such as hotels, motels, condos, and apartments are six stories or less. 
  • High-rise: hotels, condos, and apartments that are at least seven stories. 

Commercial and Residential Fire Sprinklers: CPVC has a smoke and flame resistance that makes it perfect for most housing applications such as:

  • Single-family (NFPA 13D): This includes mobile homes and standalone housing.
  • Residential (NFPA 13R): This includes structures that have at most four stories and include motels, hotels, apartments, and condos. 
  • Commercial Residential (NFPA 13): This involves structures with at least five stories and includes hotels, multi-unit buildings, condos, and high-rises. 

Conclusion

There is no argument that CPVC is the most commonly used material in the industry today. This material improves PVC in terms of chemical resistance, fire resistance, pressure resistance, and temperature resistance. 

However, each material has a unique application that we have discussed above. If you aren’t sure of the exact material you should use in your application, consult a reliable professional. We hope that you achieve effective results with the use of either CPVC or PVC materials. 

Sources

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

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