Sizes of Water Pipes Explained

Water pipes come in a variety of sizes, and understanding these sizes is crucial for any plumbing project.

The smallest size of water pipe is typically 1/4 inch, which is often used for small fixtures like faucets and toilets.

This tiny pipe is usually made of copper or PEX, and its small diameter allows for efficient water flow while minimizing water waste.

In residential areas, 1/2 inch pipes are a common sight, often used for supply lines to sinks, toilets, and washing machines.

These pipes are typically made of copper, PEX, or PVC, and their larger diameter allows for more water flow than the smaller 1/4 inch pipes.

For larger households or commercial buildings, 3/4 inch and 1 inch pipes are often used for supply lines to appliances like water heaters and dishwashers.

These larger pipes can handle higher water flow rates, making them suitable for areas with multiple users.

So, you're wondering about the types of plumbing? Well, the most common types of water supply lines are PEX, copper, galvanized, CPVC, and polybutylene.

PEX pipes are flexible and resistant to freezing, making them a popular choice for many homeowners.

Galvanized pipes are often found in older homes and are known for their durability, but they can corrode over time.

CPVC pipes are a popular choice for indoor plumbing because they're resistant to corrosion and can withstand high temperatures.

Polybutylene pipes, on the other hand, are not up to code in North Carolina and are mostly found in existing structures.

The size of the pipe you need depends on the water pressure in your home. Your local building code can provide you with a fixture unit that shows the cubic feet of water used per minute of any given appliance or fixture.

To determine the pipe size, you'll want to consult a pipe sizing chart, but first, you'll want to estimate the length of the pipes needed to supply the fixtures. Generally speaking, the main pipeline from the street to your home is either ¾ or 1 inch in diameter.

Here's a rough guide to help you get started:

Keep in mind that pipes being run to upper-level areas of your home may need to be larger than what you'd use on a ground floor or in a basement, as water pressure decreases by about a half pound per square inch for every foot a pipe extends above your water supply.

To determine the right pipe size for your project, you'll need to consider several factors. First, take note of the water pressure in your home and consult your local building code for the fixture unit rating of each appliance or fixture. This will give you a starting point for determining the best size pipe for your needs.

Your local building code can provide you with a fixture unit that shows the cubic feet of water used per minute of any given appliance or fixture. For example, a toilet typically requires a 3/8" cold water pipe, while a kitchen sink requires a ½" cold water pipe.

If you're running new lines to an upper-level area of your home, keep in mind that water pressure decreases by about a half pound per square inch for every foot a pipe extends above your water supply. This means that pipes being run to second or third floors might need to be larger than what you'd use on a ground floor or in a basement.

Here's a rough guide to common pipe sizes for different fixtures:

Remember to consult a pipe sizing chart or a plumbing expert if you're unsure about the best size pipe for your project. They can help you determine the right size pipe based on your specific needs and local building codes.

If a pipe is too small, the velocity of the water flowing through it will be too high. This can lead to several issues.

The pipe sizes may be non-compliant, which means they don't meet the required standards. This can be a problem if you're planning to sell or renovate your building.

High velocity also reduces the pipe's design life and may cause it to operate outside of the manufacturer's warranty. This can lead to costly repairs down the line.

Water flowing through a small pipe can create noise that's a nuisance to building occupants. Imagine having to live or work in a building with constant water hammer!

A small pipe can also cause a significant pressure drop through the system, resulting in low pressure at the outlets. This might require a large pump to compensate, adding to your energy bills.

Here are some potential consequences of having a pipe that's too small:

When designing pipes, there are three key parameters to consider: maximum velocity, minimum velocity, and pressure drop per meter. These parameters will help you determine the right size for your pipes.

Maximum velocity is crucial, as it can affect the efficiency and lifespan of your pipes. For example, ABS piping has different classes, with ABS 2112 being the strongest, followed by ABS1316, ABS1210, and finally ABS1208. These classes have varying burst pressures.

Pressure drop per meter is another important parameter, as it can impact the overall performance of your system. For instance, PEX tubing has a maximum allowable water pressure of 160 PSI at 73 F, which decreases to 100 psi at 180 F and 80 PSI at 200 F.

To avoid adding pumps to your project, it's essential to consider the maximum pressure drop. This will help you design pipes that don't require additional energy to run, thus reducing the carbon footprint and operational costs of your design.

Here's a rough guide to the maximum pressure ratings for different types of pipes:

Keep in mind that these are general guidelines and can vary depending on the specific pipe material, size, and temperature. Always check with the pipe manufacturer for the exact pressure ratings.

Fluid velocity is a critical parameter in pipe design, and it's essential to get it right. If the pipe is too big, the velocity will be very low, leading to excessive materials and associated costs.

Meeting the self-cleaning velocity is crucial to prevent microorganisms from building up in the pipes and reducing water quality. This is especially important in healthcare and aged care facilities.

To determine the fluid velocity, you'll need to use the first equation, which takes into account the pipe information and user-input flow rate. The calculator will automatically determine the inner area from the table within the references, but you should double-check to ensure the combination exists.

The velocity calculation is as follows: Velocity (m/s) = (Flow Rate (L/s) / 1000) / ((3.14 * (Internal Pipe Diameter (mm)/2) ^2) / 100000. This equation is used to find the velocity in the pipe.

Here's a quick reference to the velocity parameters:

The Reynolds Number is a critical factor in pipe design, helping us understand the nature of fluid flow within the pipe.

It's calculated using the velocity from the previous equation, along with the pipe's inner diameter and the fluid's properties, such as density and viscosity.

The Reynolds Number classifies fluid flow into three categories: Laminar, Transition, and Turbulent.

The breakdown between these classifications is as follows: Laminar flow is characterized by smooth, orderly motion, while Transition flow is a mix of both laminar and turbulent flow, and Turbulent flow is chaotic and irregular.

For accurate friction calculations, the fluid flow should be in the Turbulent region, which is the most common and desirable state for pipe design.

The calculator will highlight any Reynolds Number that falls below the Turbulent region in red, indicating the need for further adjustment.

Understanding the Reynolds Number is essential for designing efficient and safe pipes that can handle various fluids and flow rates.

Copper piping is a great choice for domestic water systems, as it can handle pressures up to 300 psi. However, in high-rise buildings, water pressure can exceed this limit.

Type K copper pipe is the strongest and has the highest allowable pressure, making it suitable for underground domestic water piping and areas with high pressures. Type L tubing is the second-strongest copper type and is typically used for indoor tubing with pressures below 150 psi.

CPVC piping, on the other hand, is a plastic piping that's low-cost and easy to install, but it's not suitable for high-temperature water at pressures above 100 psi. Its pressure rating drops significantly at temperatures above 73°F.

Ductile iron piping is a strong and durable option, often used for underground main piping, and can withstand high pressure loadings and corrosion. However, it's more expensive than plastic piping and requires linings to slow down corrosion.

CPVC is a type of plastic piping that's commonly used for cold water and sewer systems.

It's low cost and easy to install, making it a popular choice for many plumbing projects. However, it's not suitable for high-temperature water, and its pressure rating drops significantly above 73°F.

CPVC can handle pressures up to 300 PSI for smaller diameters and thicker pipes, but this rating decreases as the pipe size increases. For example, a 24" Schedule 40 pipe can only handle 120 PSI.

The pressure rating of CPVC piping also decreases as the water temperature increases, and it's not recommended for use with water above 180°F. In fact, the pressure rating drops to 100 PSI at this temperature.

CPVC has a larger coefficient of thermal expansion than metal piping, which means it expands and contracts more with temperature changes. This requires careful planning and accounting for pipe expansions and reductions, especially for long runs of piping.

The dimensions of CPVC piping are governed by two standards: ASTM F441 and ASTM F442. These standards provide dimensions in the Schedule and SDR formats, respectively.

CPVC piping is slightly stronger than PVC and can handle higher temperatures, but it's still not as durable as copper piping.

Polyethylene and polypropylene are types of thermoplastic materials that are not as commonly used for domestic water systems as other materials. However, they have their own advantages and disadvantages.

These materials are resistant to corrosion and can be used for fluids that are not chemically compatible with metal pipes. They are also cheaper and easier to work with than metal pipes.

But, these plastics are not as long lasting as their metal counterparts and do not do well when exposed to UV, unless the plastic has a UV coating. Some polyethylene pipe can be constructed with UV resistance built-in.

Polyethylene and polypropylene piping can range from sizes ½” to 65” but the most common sizes for domestic water systems are typically smaller. The applicable standards for these piping materials are ASTM D 2239, AWWA C901, and ASTM D 2737.

There are different types of PE and PP materials, classified by a four-digit material code. The first two digits classify the cell, which determines the material's density, tensile strength, slow growth crack resistance, and more.

Pressure ratings are a crucial aspect of pipe materials. Copper piping, for example, has a pressure rating of 300 psi in domestic water systems, but can exceed 300 psi in high-rise buildings.

Type K copper tubing is the strongest and has the highest allowable pressure, making it suitable for underground domestic water piping, as well as high-pressure applications.

Type L copper tubing is the second-strongest and has a maximum allowable pressure of 150 psi for larger tube diameters, making it suitable for above-ground installations.

ABS piping, on the other hand, has different classes with varying pressure ratings, with ABS 2112 being the strongest and ABS 1208 being the weakest.

PEX tubing has a maximum allowable water pressure of 160 psi at 73 F, but decreases to 100 psi at 180 F and 80 psi at 200 F.

Galvanized steel pipes have pressure ratings ranging from 2,000 psi for small pipes to 200 psi for larger pipes and lower schedules.

Plastic piping, including PE and PP, has pressure ratings ranging from 160 psi to 63 psi, but these ratings are only for 73 F and decrease as temperature increases.

Stainless steel pipes have pressure ratings ranging from 2,000 psi for small pipes to 200 psi for larger pipes and lower schedules, with 304 pipes being stronger than 316 pipes.

Ductile iron water pipe has different pressure classes, including 350 PSI, 300 PSI, 250 PSI, 200 PSI, and 150 PSI, with the higher classes having increased thickness and smaller inner diameters.

ASTM D 1527 Schedule 40 & 80 is a crucial aspect of understanding pipe materials and ratings.

Schedule 80 piping has thicker walls than schedule 40, resulting in a higher pressure rating. This means it can handle more pressure than schedule 40 piping.

The pipe schedule describes the thickness and pressure rating for each pipe size. The schedule number directly affects the pipe's pressure rating.

Schedule 40 and Schedule 80 piping have the same outside diameter, but their thicknesses are different. This allows pipes of different schedules to be joined together.

The inner diameter of schedule 80 piping is smaller than schedule 40 piping due to its thicker walls. This affects the flow rate and capacity of the pipe.

Table 4 shows the pipe dimensions for schedule 40 ABS plastic piping in accordance with ASTM D 1527. The tables provide a clear and concise comparison of pipe dimensions between schedules.

Table 5 shows the pipe dimensions for schedule 80 ABS plastic piping in accordance with ASTM D 1527.