In our day to day lives, a schedule simply means a plan of carrying out certain tasks within a given time duration. Scheduling is however a very different concept in plumbing.
If you are in the market for PVC pipes, the 2 terms you will be bombarded with are schedule 40 and schedule 80 PVC pipes.
So, what is the difference between schedule 40 and schedule 80 PVC pipes? And where is each applied?
The main difference between schedule 40 and schedule 80 PVC pipes is their wall thickness. Schedule 80 PVC pipes have thicker walls than schedule 40 PVC pipes (of the same outside diameter) and are therefore stronger and able to handle more pressure.
In terms of applications, schedule 40 PVC pipes are used in residential drainage (like sewer lines) while schedule 80 PVC pipes are used in commercial and chemical applications due to their thick walls and therefore high pressure rating.
Although schedule 40 and 80 PVC pipes have the same outer diameter and therefore easy to connect, they should not be mixed. Schedule 80 PVC pipes are used for high pressure applications and mixing them with schedule 40 fittings compromises the integrity of the entire pipe network.
As we are often reminded, a pipe is only as strong as its weakest link. If you therefore mix a schedule 80 PVC pipe with a pressure rating of 400 psi with a schedule 40 fitting with a pressure rating of 280 psi, the overall pressure rating of the entire pipe network is 280 psi.
Having said that, I don’t see a problem using a schedule 80 PVC pipe or fitting in a pipe network with schedule 40 PVC pipes. In short, you can higher but not lower.
Although not always the case, schedule 40 PVC pipes are mostly white in color while schedule 80 PVC pipes are grey. It is however important to check the pipe’s label to be sure since some manufacturers deviate from this practice.
Scheduling In Plumbing
Most people confuse scheduling in plumbing because of terms like wall thickness, outside diameter, inside diameter, width, nominal size etc.
You however don’t need to be confused. It is a very simple concept developed by the American Society for Testing and Materials (ASTM).
In plumbing, scheduling simply refers a standard which outlines how thick a pipe’s wall should be, relative to its width, also known as diameter.
As I have already mentioned, a schedule 40 pipe has thinner walls than a schedule 80 pipe of the same nominal size. Simply put, as a pipe’s schedule increases, its wall thickness increases as well.
It is important to understand that scheduling does not affect the outside diameter of a pipe. The variable in all this is the pipe’s thickness which directly corresponds to the inner diameter.
Needless to say, a schedule 40 pipe will have a larger inside diameter compared to a schedule 80 pipe of the same outside diameter. The schedule 80 pipe will however have a higher pressure rating than the schedule 40 pipe.
To put this into perspective, a 2-inch schedule 40 PVC pipe will have a 0.154’’ minimum wall thickness and a pressure rating of 280 psi while the same size of a schedule 80 PVC pipe will have a 0.218 minimum wall thickness and a pressure rating of 400 psi.
Pipe scheduling is important in determining what kind of pipe is best suited for a certain application. This should tell you that no pipe is better than the other but it actually depends on where the pipe will end up being used.
The Difference Between Plumbing PVC and Electrical Conduit PVC
PVC pipes are not only used in plumbing but also in electrical applications. However, the PVC pipes used in plumbing are not the same pipes used in electrical installations.
The main difference between plumbing PVC pipes and electrical conduit PVC pipes is that plumbing PVC pipes are pressure-tested while electrical conduit PVC pipes are not. This means the two pipes cannot be used interchangeably.
And it makes perfect sense. In plumbing PVC pipes, there will be fluids flowing inside the pipes under pressure and you therefore want to be sure that the pipe can withstand the pressure.
On the other hand, electrical current is never under any pressure and the pipes are only there to protect the cables. Pressure-testing these pipes is therefore not of any importance.
It is therefore very important to let the hardware store know what exactly you need to do with the pipes to ensure that you buy the right pipes.
Having said, there will be no harm in using plumbing PVC pipes in electrical applications. You however cannot use electrical conduits PVC pipes in plumbing applications.
Schedule 40 PVC pipe is better than schedule 80 PVC pipes when used as an electrical conduit since it has a larger internal diameter which makes pulling wires through it easier. It is however a good idea to use schedule 80 PVC pipes in high traffic areas to prevent damages thanks to its thick walls.
Schedule 40 vs Schedule 80 PVC pipes
Let us now dig deeper into the major differences between schedule 40 and 80 PVC pipes.
1. Wall Thickness
As I previously mentioned, wall thickness is the main difference between schedule 40 and schedule 80 PVC pipes. To help you remember it, just know schedule 80 pipes have a thicker wall have a larger wall thickness than schedule 40 pipes.
This therefore means that more material is used to make schedule 80 PVC pipes which make them stronger and rigid compared to schedule 40 pipes. As a result, they are able to withstand more pressure than the schedule 40 pipes of the same outside diameter.
Schedule 80 PVC pipes are used in industrial and chemical applications where they meet and even exceed the require pressure requirements of the fluids they transport.
An important point to remember is that PVC, being plastic is affected by heat. A pipe with thin walls will easily be softened by hot fluids while a thick and tough pipe will hold just fine, which is why schedule 80 PVC pipe are well-suited for industrial applications.
It goes without saying that schedule 80 PVC pipes have a smaller internal diameter than their schedule 40 counterparts. That means reduced volume of the liquid being transported when comparing pipes with the same outside diameter.
This should however not be a big concern since you can opt to use a slightly large pipe if you have a lots of liquids to move.
For instance a 2-inch (nominal) schedule 40 PVC pipe has an internal diameter of 2.047 inches wile a 2-inch schedule 80 PVC pipe has an internal diameter of 1.913 inches. If that is not sufficient for your application needs, you can opt to go with the 2-1/2’’ pipe with an internal diameter of 2.29 inches.
2. Pressure Rating
The pressure rating of both schedule 40 and schedule 80 PVC pipes is directly proportional to their wall thickness. The pipe with the thicker walls (schedule 80) will withstand more pressure than schedule 40 pipe before, bursting.
There is one thing I don’t want you to misunderstand though. In the case of schedule 40 and 80 PVC pipes, we are not talking about the pressure of the liquid inside the pipe, but the pressure limit of the pipe.
It is common knowledge that liquids have a high pressure when flowing through thin pipes compared to large pipes.
Now, although schedule 40 and 80 PVC pipes are of the same nominal size, schedule 80 pipes have a smaller internal diameter which means liquids flowing through a 2-inch schedule 80 pipe will have a high pressure than those flowing through a 2-inch schedule 40 pipe.
That is not the pressure that matters in this case. What matters is the pressure the pipe can withstand before it bursts.
These tests are usually carried out in controlled environment and if for instance a certain pipe is rated 400 pounds per square inch, it does not mean it will burst at that pressure. There is usually a safety net. Such a pipe would probably burst at between 450 and 500 psi.
3. Cost
Due to the extra wall thickness in schedule 80 PVC pipes, more PVC materials is needed to make them compared to schedule 40 PVC pipes. As a result, schedule 80 PVC pipes are more expensive compared to schedule 40 pipes.
The extra pipe used to make schedule 80 PVC pipes also makes them heavier compared to schedule 40 pipes of the same size. They are therefore harder to install which means more people will be involved in handling them.
You shouldn’t however choose a pipe schedule based on cost. Consider your needs first then purchase the pipe with the appropriate schedule.
4. Color
Traditionally, schedule 40 PVC pipes are while in color while schedule 80 PVC pipes are grey. That is however not always the case as some manufacturers deviate from this norm and it is importantly not a code requirement.
It is therefore always important to make sure that you properly indentify the pipe before purchasing it. Good thing is that the pipes are always labeled with the specific schedules indicated.
Schedule 40 vs 80 PVC Pipes Comparison Table
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Which Schedule of PVC Pipes Should I use?
Although I have said that schedule 80 PVC pipe have thicker walls and therefore higher pressure rating, that does not mean they are the best pipes to use. Each schedule of pipes has its places where it is best suited.
If you have a project that is industrial or one involving chemical process, schedule 80 PVC pipes are what you should go for.
For someone looking to install pipes in the house in the drain waste and vent system, schedule 40 PVC will be ideal, Not only will they meet and exceed your pressure specifications but they will also save you some money.
As you shop for the pipes, do not forget that the fittings also come in the 2 schedules. That means that if you decide to work with schedule 40 PVC pipes, all the elbows, tee and couplings should also be of that schedule.
Related: PVC vs ABS pipes
And basically those are the difference between schedule 40 PVC pipes and schedule 80 PVC pipes. I hope this guide was helpful.
FAQs
Do I need Schedule 40 or 80 PVC? ›
Each one has its benefits in different applications. Schedule 40 pipe has thinner walls, so it is best for applications involving relatively low water pressure. Schedule 80 pipe has thicker walls and is able to withstand higher PSI (pounds per square inch). This makes it ideal for industrial and chemical applications.
Which PVC pipe is best for plumbing? ›PEX. PEX piping is a flexible plastic piping that has become a popular selection in residential and small business applications. Although slightly higher initial cost, its minimal maintenance, and fast installation process make it the best pipe for water distribution inside a building.
When should you use Schedule 80 PVC? ›What is schedule 80 PVC used for? Because schedule 80 PVC is a thicker pipe, it is usually is used for applications that are commercial or industrial in nature. These more demanding applications generally require piping that will stand up to high pressures and harsh environments.
Can you use Schedule 40 PVC for house plumbing? ›It will degrade when exposed to UV light (such as sunlight), and also high temperature. Its pressure rating is to be derated at high temperatures. Because of this, PVC is not approved for use in houses for potable water.
Where is Sch 80 PVC required? ›The only time schedule 80 PVC conduit would be required is when the service cable is exposed to physical damage. The AHJ needs to determine if the cables are exposed to physical damage since there is not a definition of physical damage in the code.
How long will Schedule 40 PVC pipe last? ›As one of the most-used plumbing materials, PVC pipe is known for being very durable and long-lasting. In fact, PVC pipes last approximately 100 years.
What is the best pipe to use for residential plumbing? ›PVC pipe is by far the most commonly used pipe in residential homes. This type of pipe is affordable and available in a number of different fittings and sizes. It's also a great choice for most warm and cold water applications.
What plumbing pipes last the longest? ›Drainage pipes are often made of cast iron or polyvinyl chloride, or PVC. Cast iron will last anywhere from 75-100 years while PVC wins the award for longest-lasting pipe material with an indefinite lifespan.
How long will schedule 80 PVC last? ›| Underground placed pipes' lifespan | |
|---|---|
| Pipe material | Expected lifespan |
| PVC pipes | 70 to 100 years |
| Cast iron pipes | 70 to 100 years |
| Copper pipes | 70 to 80 years |
Schedule 80 pipes have a thick wall and are used for high pressure operations in a commercial and industrial setting. Schedule 40 pipes have thinner walls and are intended mostly for residential settings.
Can you mix Schedule 80 and Schedule 40 PVC? ›
Thicker is always better - Myth
Schedule 40 pressure fittings are used in applications such as potable water, irrigation, golf course construction, and pool & spa. Even though it is possible to combine schedule 80 and schedule 40 PVC together it is not recommended.
The short answer: No. Explanation: PVC is a thermoplastic, and therefore, at some point it will begin to degrade and break down as it's heated up. It just so happens that Schedule 40 PVC's maximum operating temperature is 140 degrees Fahrenheit, around the same temperature that hot water gets to in most homes.
Is Schedule 80 PVC safe for drinking water? ›Westlake Pipe & Fittings Schedule 40, Schedule 80 and insert fittings are listed with the National Sanitation Foundation (NSF) for use in potable water applications and comply with Standard 14 and 61.
Can you use Schedule 40 for sink drain? ›He uses thick “schedule 40” plastic (PVC or ABS) parts that are “welded” together with solvent cement for sink drain plumbing. An assembly like this will last forever, no matter how times you bash it with the wastebasket. Be sure to install a union trap and a rubber coupler so you can open the trap to clear clogs.
How deep does Schedule 40 PVC need to be buried? ›What is the minimum depth for placing Schedule 40 PVC conduit below a concrete slab? A. If it's under a building, there is no depth requirement. If it's placed outside under a concrete slab, then the minimum cover is 4 inches [Table 300.5].
What schedule PVC is the strongest? ›Schedule 40 PVC pipe is strong, rigid, and can handle pressure applications. For jobs that require a higher pressurization though, schedule 80 pipe is better suited. Most PVC pipe and fittings have a maximum pressure rating listed so you know what it can handle.
How hot can schedule 40 PVC get? ›The maximum recommended temperature for Schedule 40 PVC is 130°F. PVC Schedule 40 pipe and fittings can be joined using solvent cements.
How much pressure can schedule 40 PVC take? ›Example: What's the Maximum Working Pressure of a 6” Schedule 40 pipe length at 110 degrees Fahrenheit? Answer: 180 PSI X . 51= 91 PSI max at 110 degrees.
What type of pipe is no longer used in plumbing? ›This became so common, a class-action lawsuit was filed in the 1990s, ultimately halting the use of polybutylene pipes.
What type of pipe is not recommended for water line? ›Avoid using polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC). These pipes contain the highest levels of chemicals of concern and they are typically installed using hazardous solvents.
What is the most popular type of piping used today in residential installation? ›
Cast iron had been the most frequently used material in home construction and is still popular, but PVC and ABS are the materials most frequently used in new home construction. Instead of replacing all of your cast iron pipes, you can just replace the rusted sections with PVC or ABS.
Are PVC pipes OK for plumbing? ›Polyvinyl Chloride Pipes (PVC) pipes won't rust, corrode, or degrade over time, are excellent for sink, toilet, and bathtub drain lines or vent stacks, can readily handle high water pressure, and are inexpensive and easy to work with. Their biggest drawback is that they can only be used for cold water.
Can I use PVC for shower plumbing? ›PVC is a plumbing pipe known for its versatility, lightweight, and blockage resistance. PVC piping is generally used as part of a sink, toilet, or shower drain line, though it's sometimes used as a home's main water supply pipe.
What kind of pipes do plumbers use? ›Copper and PEX are the most common pipe materials used in homes. Copper pipes are durable, corrosion-resistant, and can be used for hot and cold water. PEX seems to be replacing copper pipes at a high rate since it is less expensive, more flexible, and easier to install.
How many years will PVC pipe last? ›Based on stress regression, slow crack growth and fatigue testing, the service life of PVC pressure pipe should exceed 100 years. The Water Research Foundation reported that 100 years is a conservative estimate for a properly designed and installed PVC pipe.
What is the lifespan of PVC water pipes? ›Because PVC is immune to corrosion, a minimum service life of at least 100 years can be expected. This figure is supported by a number of independent studies, as well as the experience of many long-term users of PVC piping systems.
Do you need special glue for Schedule 80 PVC? ›For Schedule 80 PVC pipe and fittings, you should always use the heavy body cement due to the increased wall thickness.
What is the difference between Schedule 40 and Schedule 80 pipe? ›The major difference between schedule 40 and schedule 80 pipe is the wall thickness, inside diameter, and their weight. Schedule 80 will have a greater wall thickness, a smaller inside diameter and a higher weight than Schedule 40 pipe at a given nominal pipe size.
What temperature can Schedule 80 PVC withstand? ›Conclusion: All sizes of Schedule 80 PVC and CPVC thermoplastic pipe are suitable for vacuum service up to 140°F and 30 inches of mercury. In addition, CPVC may be used up to 210°F.
Can Schedule 80 PVC be buried? ›Schedule 40 PVC and schedule 80 PVC rigid conduit is ideal for underground applications using concrete-encased or direct burial installation, as well as exposed or concealed above-ground applications.
How often does Schedule 40 PVC need to be supported? ›
How often does Schedule 40 PVC need to be supported? PVC conduit must be secured within 3 ft. of each outlet box, junction box, device box, conduit body, or other conduit termination. PVC must be supported every 3 ft.
Why is Schedule 80 PVC so expensive? ›For the general cost, schedule 80 PVC is more pricey as it is made with more PVC materials and material walls to handle higher pressures and temperatures.
Can Schedule 40 PVC be used for cold water? ›PVC Schedule 40 Pipe is for cold water pressure systems where temperatures will not exceed 140 F. They are highly resilient, with high-tensile and high-impact strength.
What kind of PVC is used for sink drains? ›PVC is made in several different grades: schedules 40 and 80 and chlorinated polyvinyl chloride (CPVC). Their uses are as follows: Schedule 40 is most commonly used for drain-line piping under houses.
Can I use Schedule 40 PVC for pool plumbing? ›Schedule 40 PVC pipe is suitable for nearly all residential pool plumbing, Schedule 80 is not commonly used on pools, mainly due to its much higher cost. Schedule 80 pipe has the same outside diameter as Schedule 40, but because it's thicker, has a 6% smaller internal diameter.
Is Schedule 40 or 80 stronger? ›Schedule 80 pipe is designed with a thicker wall. This means the pipe is thicker and stronger, and as a result it can handle higher pressures. You are probably most familiar with schedule 40 PVC pipe.
Are Schedule 40 and 80 fittings interchangeable? ›Thicker is always better - Myth
Schedule 40 pressure fittings are used in applications such as potable water, irrigation, golf course construction, and pool & spa. Even though it is possible to combine schedule 80 and schedule 40 PVC together it is not recommended.
Schedule 40 pipes are commonly used for drainage around buildings and for gas and water lines. The pressure rating for this pipe schedule is 120 to 810 pounds per second inch (PSI). As a result, schedule 40 pipes are commonly used for potable water systems, golf course construction, or pools and spas.
Where can schedule 40 PVC conduit be used? ›Schedule 40 PVC Conduit electrical pipe is used for electrical wiring in walls, floors and ceilings in accordance with NEC 352. According to NEC 352 it can also be buried directly into the earth, encased in concrete, and used in areas exposed to direct sunlight.
Can you use Schedule 40 PVC for hot water? ›The short answer: No. Explanation: PVC is a thermoplastic, and therefore, at some point it will begin to degrade and break down as it's heated up. It just so happens that Schedule 40 PVC's maximum operating temperature is 140 degrees Fahrenheit, around the same temperature that hot water gets to in most homes.
How does Schedule 80 compare to Schedule 40? ›
The major difference between schedule 40 and schedule 80 pipe is the wall thickness, inside diameter, and their weight. Schedule 80 will have a greater wall thickness, a smaller inside diameter and a higher weight than Schedule 40 pipe at a given nominal pipe size.
Can you use GREY PVC for water? ›Gray conduit is not rated for pressure pipe applications and may not be suitable for potable water use. Stabilizers and other ingredients used in conduit PVC may be toxic; conduit PVC is not held to the same drinking water standards as NSF marked pipe and should not be used in potable water systems.
Can you glue white PVC to GREY PVC? ›Yes. Clear PVC pipe can be cemented to gray and white PVC by using PVC pipe cement.
Do you use Schedule 40 for plumbing? ›For most water transportation purposes, the pipes most commonly used are those designated as Schedule 40 and Schedule 80 pipes. Both Schedule 40 and Schedule 80 PVC pipes have the same external diameter, however, they have some key differences.
What is the difference between white and gray Schedule 40 PVC? ›PVC pipe that is used for plumbing is usually white while electrical conduit PVC is usually gray. These are the standard colors, but you can find PVC that has had chemical additives added during the manufacturing process to create different colored pipes.