How to Shop for PEX Pipe – Pipe Types and Sizing

When embarking on the task of sizing a PEX piping system with ASTM F1960 fittings, you have three primary methods at your disposal.

Fixture Unit Tables

Begin with model code fixture unit tables to guide your sizing decisions. This approach is suitable for systems that fall within the parameters outlined in these tables. Using these provides a structured starting point, though they are only applicable to straightforward installations.

Residual Pressure Assessment

This method focuses on identifying the most remote or demanding fixture to calculate the system’s critical path. By assessing friction-loss data, you can gauge the pressure available from the fixture back to the water source. This often requires adjusting pipe sizes; high-loss segments for cold water might need upsizing, while certain hot-water segments could potentially be reduced, thanks to the differing design velocities between copper and PEX pipes.

Uniform Friction Loss Method

The third method looks at the overall physical layout of the structure. Here, you’ll need information such as the available static pressure, the building’s height, and the furthest distance to a fixture. With this data in hand, calculate a pressure loss per 100 feet (or per foot). This number will guide you in determining the appropriate pipe sizes throughout the system, ensuring efficient water delivery

By carefully selecting and applying the right method, you can ensure an optimal PEX piping system tailored to your specific needs.

PEX piping, known for its flexibility and durability, behaves uniquely when exposed to varying temperatures. This behavior is mainly due to the expansion and contraction properties of the material in response to temperature changes.

Expansion and Contraction Rates

When the temperature of the fluid running through a PEX pipe changes, the pipe expands or contracts. Specifically, PEX piping expands approximately 1.1 inches for every 100 feet of pipe per 10°F change in temperature. This means that if the fluid temperature fluctuates significantly, the PEX pipe will noticeably expand or contract.

Managing the Effects

To manage this natural expansion and contraction, steel support channels are typically used. These supports can be snapped onto the pipe, providing continuous reinforcement for suspended systems. When combined with strategically placed fixed points, these supports significantly reduce the expansion and contraction impact, bringing it closer to that observed in metal piping systems.

Securing the Supports

It’s essential to secure these support channels adequately. This typically involves using straps with a minimum tensile strength of 300 pounds. These straps must also meet the system’s temperature requirements and be resistant to UV light if exposed, ensuring they maintain integrity over time.

Considerations for Support Spacing

The spacing of supports and placement of fixed points will vary based on several factors:

• Operating Temperature: Higher temperatures generally necessitate more fixed points.
• Ambient Environment: The surrounding temperature can impact expansion and contraction rates.
• Length of the Piping Run: Longer runs may require additional fixed points to maintain structural integrity and aesthetic appeal.

In conclusion, understanding how PEX pipes react to temperature variations is crucial for maintaining a functional and aesthetically pleasing piping system. With proper support and strategic placement, these pipes can perform efficiently under various conditions.

PEX pipes are designed to bend and adapt to changes in direction, which eliminates the need for numerous elbows and additional fittings. This adaptability allows for a smoother, more direct path for water or other fluids.

Key Benefits:

• Reduced Fittings: By minimizing the number of joints and fittings needed, the risk of leaks is decreased. This also results in a less obstructed path for fluid movement, thereby enhancing flow rates.
• Lower Pressure Drop: The seamless nature of PEX piping means there’s less resistance to flow. When the fluid moves through a system with fewer bends and interruptions, pressure is maintained more effectively over the entire length of the pipe.

By using PEX, systems experience improved efficiency, as the design allows for optimal fluid dynamics with minimal loss of pressure.

When planning PEX piping installations, it’s crucial to consider both operating and ambient temperatures, as they play a significant role in determining the appropriate support spacing and fixed-point placement.

Impact of Temperatures on PEX Systems

1. Operating Temperature:
   • As the operating temperature increases, PEX piping tends to expand. This expansion requires more fixed points to ensure that the system remains stable and retains its aesthetic appeal.
   • Higher temperatures may demand narrower spacing between supports to prevent sagging or distortion of the pipes.
2. Ambient Temperature:
   • Fluctuations in ambient temperature can lead to variations in the length of the PEX pipes. This expansion and contraction necessitate strategic placement of fixed points.
   • Colder environments might reduce the spacing needed as PEX could shrink slightly, whereas warmer ambient conditions would require adjustments to accommodate expansion.
3. Length of the Piping Run:
   • Longer piping runs increase the potential for temperature-induced expansion. To counteract this, additional fixed points and closer support spacing are essential to maintain system integrity.

Key Considerations

• Material Properties: The inherent flexibility of PEX allows for some temperature-related movement, but improper support can lead to performance issues.
• System Design: Engineers and installers should consider both current and potential future temperature changes to optimize support placement.

Addressing these temperature-related factors ensures a reliable, long-lasting PEX piping system with minimal maintenance concerns.

Resources and Tools for Effective PEX System Design and Installation

Professionals seeking to optimize PEX systems can rely on a variety of resources and tools tailored for precise design and installation. Here’s a breakdown of what’s available:

1. Online Calculators:

Many manufacturers offer free online calculators that simplify the complexities of pipe sizing. These tools provide instant calculations for plumbing systems, hydronic piping, radiant systems, and even pipe heat loss, ensuring efficiency and accuracy in design.

2. Digital and Print Design Manuals:

Detailed design manuals, available both digitally and in hard copy, offer comprehensive guidance on creating high-performing PEX systems. These manuals typically include tables and charts that are indispensable for accurate planning.

3. Best Practices Guides:

Leveraging the expertise outlined in best practice guides can significantly enhance the performance and reliability of PEX installations. These resources focus on expert-recommended techniques that help ensure durability and effectiveness in system operation.

4. Educational Workshops and Webinars:

Participate in workshops and webinars to gain hands-on knowledge and stay updated with the latest trends and technologies in PEX installation. These sessions often feature experts who can provide deeper insights into tackling common challenges.

5. Professional Forums and Networks:

Engaging with online forums and professional networks can provide real-world insights and peer support. These platforms allow professionals to share experiences, troubleshoot issues, and learn about innovative approaches from their peers.

By utilizing these tools and resources, piping professionals can achieve exceptional results in designing and installing PEX systems, ultimately contributing to the advancement of the commercial construction industry.

To ensure reliable PEX fitting connections, knowing the relevant ASTM specifications is essential. Here’s a breakdown of the key specifications that you need to keep in mind:

1. ASTM F1807

This specification covers metal insert fittings that use a copper crimp ring, ideal for securing SDR9 Cross-linked Polyethylene (PEX) and SDR9 Polyethylene of Raised Temperature (PE-RT) tubing.

2. ASTM F2159

Designed for plastic insert fittings, this standard also uses a copper crimp ring for attaching to SDR9 PEX and PE-RT tubing, providing a versatile and durable connection method.

3. ASTM F2098

Focuses on stainless steel clamps specifically formulated to secure SDR9 PEX tubing to both metal and plastic insert fittings. These clamps offer a reliable grip and maintain the integrity of the connection.

4. ASTM F877

Covers the standard specifications for PEX plastic hot and cold-water distribution systems. This includes a wide range of distribution applications where PEX is used as an efficient piping solution.

5. ASTM F1960

This specification is for cold expansion fittings that incorporate PEX reinforcing rings. They provide a robust connection by adhering to the expansion method for joining PEX tubing.

Each of these specifications plays a critical role in the selection and installation of PEX fitting connections, ensuring the system’s efficiency and longevity.

PEX in-slab installations come with a host of benefits that make it a popular choice for building projects:

• Flexibility: The adaptable nature of PEX allows it to easily navigate around obstacles, making installations more straightforward and less time-consuming.
• Cost Efficiency: By eliminating the need for hangers in the installation process, PEX reduces both product and labor costs, contributing to overall project savings.
• Versatility: PEX is available in pre-sleeved coils that are perfect for direct slab applications, but its utility doesn’t stop there. It can also be used bare, offering durability and functionality in concrete, below-grade, and even water-service scenarios.

These features make PEX a smart and economical choice for efficient in-slab installations.

Why Do Professionals Prefer ASTM F1960 Fittings for PEX Systems?

Professionals across both residential and commercial sectors favor ASTM F1960 fittings for PEX systems, and for good reason. These fittings are highly valued due to their user-friendly design, making them easy to install even for those new to the field.

Reliability and Performance

The reliability of ASTM F1960 fittings is unparalleled. They offer a foolproof connection which cannot be dry-fitted, ensuring a secure and trustworthy installation every time. This means fewer risks of leaks or failures, which translates to peace of mind for both installers and property owners.

Superior Flow Rates

Not only do they provide dependable connections, but ASTM F1960 fittings also excel in performance. For instance, when using a 1-inch engineered polymer (EP) fitting from this system, users can achieve a significantly enhanced flow rate. This particular fitting type boosts flow by 67% compared to F2159 plastic fittings and by 22% over F1807 brass fittings, both measured at a velocity of 8 feet per second.

In conclusion, ASTM F1960 fittings are the go-to choice for many professionals due to their ease of use, reliability, and exceptional performance in improving water flow within PEX systems.

Recommended Support Channels for PEX Piping Expansion and Contraction

When managing expansion and contraction in PEX piping, it’s crucial to choose the right support channels. Here’s what you should consider:

1. Material and Strength: Opt for support channels utilizing straps that boast at least a 300-pound tensile strength. This ensures they can securely hold the piping in place during expansion and contraction.
2. Temperature Tolerance: Ensure the straps are compatible with the temperature requirements of your piping system. This prevents material failure under varying thermal conditions.
3. UV Resistance: In areas exposed to sunlight, select straps that can endure specific UV levels to prevent degradation over time.

By focusing on these factors, you can effectively manage the dynamic movements inherent in PEX piping systems, reducing the risk of damage and maintaining system integrity.

How Does the Elasticity of PEX Pipe Benefit Public Fixtures and Fast-Acting Valve Applications?

Enhanced Pressure Absorption

One of the standout benefits of PEX piping is its remarkable elasticity, which allows it to handle sudden pressure changes effectively. For applications involving public fixtures and fast-acting valves, this flexibility is invaluable. PEX can absorb surge pressures 18% to 40% higher than those withstandable by traditional metallic pipes, reducing the risk of damage and extending the lifespan of the plumbing system.

Superior Noise Reduction

PEX piping doesn’t just excel in pressure management—it’s also a top performer when it comes to noise reduction. In environments where fast-acting valves are used, noise can become a significant issue. The elasticity of PEX dulls sound much more efficiently than metal, cutting down on noise pollution by absorbing sound vibrations that would otherwise echo through rigid piping structures. This leads to quieter, more pleasant public facilities.

All

Overall, the elasticity of PEX not only boosts durability and safety in environments with fast-acting plumbing systems but also enhances the auditory environment, making it an ideal choice for public and commercial installations.

How the Darcy-Weisbach Formula Enhances Friction Loss Data Accuracy for PEX Systems

The Darcy-Weisbach formula significantly improves the accuracy of friction loss data in PEX (cross-linked polyethylene) systems by employing a precise and universal approach. Unlike other formulas, such as the Hazen-Williams equation, the Darcy-Weisbach formula does not rely on correction factors for varying water temperatures, which can introduce errors.

Key Advantages:

• Temperature Independence: By calculating flow characteristics without temperature correction factors, it offers consistent results across a range of operating conditions.
• Empirical Validation: Its calculations are often backed by empirical laboratory data, ensuring that the friction loss predictions are reliable and evidence-based.
• Universal Application: This formula is applicable to various types of fluids and materials, making it versatile for different PEX system designs.

Incorporating the Darcy-Weisbach formula into the design and analysis of PEX plumbing systems ensures that sizing and efficiency are optimized, leading to better overall system performance.

A Logic design in PEX piping is an innovative system that blends the strengths of both trunk-and-branch and homerun systems while addressing their respective drawbacks.

Here’s how it stands out:

• Efficiency with Multiport Tees: The Logic design uses multiport tees, a feature that reduces the number of fittings needed compared to a traditional trunk-and-branch system. This not only simplifies the installation but also enhances water flow efficiency.
• Reduced Material Requirements: Unlike the homerun system, which demands a significant amount of piping to connect individual fixtures directly to a central manifold, the Logic design minimizes the total pipe required. This more streamlined approach results in cost savings and reduced material waste.

In summary, the Logic design offers an optimized PEX piping solution that balances the flexibility of trunk-and-branch systems with the material efficiency of a homerun system, making it a preferable choice for many plumbing projects.

When selecting the right pipe size for your plumbing system, it’s crucial to consider both general guidelines and detailed methodologies to ensure optimal performance. The diameter you choose will depend on the specific requirements of your plumbing system. For instance:

• 1/2 inch PEX is commonly used for smaller applications like residential water supply lines.
• 3/4 inch and 1 inch PEX are often used for larger supply lines or commercial applications.

To ensure you’re choosing the correct size for different fixtures and applications, consider these comprehensive methods:

Use Model Code Fixture Unit Tables:

Reference these tables to guide your pipe size selection according to fixture units. This method ensures compliance with standardized codes and is particularly useful for systems within predefined parameters.

Residual Pressure Method:

Assess the unique demands of your system by focusing on the most remote or demanding fixtures. Calculate system loss from the fixture back to the source using friction-loss data. This approach helps in maintaining adequate pressure and provides insights into when up-sizing or downsizing is necessary.

Uniform Friction Loss Method:

Tailor your pipe sizing to the specific conditions of your structure by considering available static pressure, building height, and fixture distance. This detailed analysis allows for precise calculations of pressure loss over distance, offering a customized solution for your plumbing needs.

By integrating these detailed approaches, alongside general diameter guidelines, you can ensure a balanced and effective design for your plumbing system, no matter the scale or scope.a

PEX pipe is a type of flexible plastic tubing used in plumbing and heating systems. Unlike traditional rigid pipes, PEX is known for its versatility, resistance to scale and chlorine, lower shipping costs, and ease of installation.

In residential and commercial construction, PEX offers numerous advantages:

• Flexibility and Fewer Fittings: The flexible nature of PEX allows it to bend around corners without additional fittings. This reduces the number of connections needed, improving flow rates and minimizing pressure loss.
• Installation Efficiency: With larger pipe sizes available, PEX is increasingly used in commercial projects due to its ease of installation. It requires fewer tools and labor, cutting down on installation time and costs.
• Safety and Transport: Lighter than metal pipes, a 300-foot coil of 1/2-inch PEX weighs just 18 pounds compared to 85.5 pounds for the same length of copper. This not only enhances job-site safety by reducing the need for heavy lifting equipment but also simplifies transport.
• Durability and Performance: PEX’s elasticity allows it to handle surge pressures 18% to 40% greater than metallic piping, making it ideal for high-demand applications. Additionally, it absorbs sound more effectively, reducing noise by up to eight times compared to metal pipes.
• Design Flexibility in Commercial Projects: PEX enables efficient plumbing designs, such as back-to-back bathroom setups, which decrease the need for numerous risers and penetrations. This is particularly beneficial in large commercial buildings, where space and efficiency are paramount.
• Adaptability for In-Slab Use: Its flexibility allows PEX to navigate around obstacles during installation, eliminating the need for hangers and further reducing labor and material costs.

By understanding these benefits, professionals can leverage PEX to enhance efficiency, safety, and overall cost-effectiveness in their construction projects.

Unlike traditional rigid pipes, PEX is known for its versatility, resistance to scale and chlorine, lower shipping costs, and ease of installation. But what makes PEX stand out even more is its significant advantage in safety and transport over metal piping systems.

Lightweight Advantage

• Reduced Weight: A 300-foot coil of 1/2-inch PEX weighs just 18 pounds, compared to the hefty 85.5 pounds of the same length in copper. This drastic weight difference not only slashes shipping costs but also makes handling far simpler.
• Job-Site Safety: The lighter weight of PEX contributes to greater job-site safety. Workers face less risk of injury from heavy lifting, enhancing the overall safety environment.

Easier Transport and Installation

• Transport Options: With its featherweight characteristics, PEX allows for easier transport options, eliminating the need for heavy lifting equipment on construction sites.
• Installation Simplicity: The flexibility and reduced weight of PEX make it extremely easy to maneuver and install, reducing labor time and cost.

By combining these attributes, PEX emerges as a superior choice for those seeking a piping solution that excels in safety, ease of transport, and overall efficiency.