Break Tank Size Calculator

What is a Break Tank?

A break tank, also known as an expansion tank or pressure tank, is a device installed in a plumbing system to accommodate changes in water pressure. It acts as a buffer between the water supply and the plumbing system, absorbing pressure surges that can occur during normal operation or emergencies.

The primary functions of a break tank include:

• Absorbing pressure surges to protect pipes and fixtures
• Providing a temporary storage space for water during pressure fluctuations
• Helping to maintain consistent water pressure throughout the system
• Preventing pipe bursts and leaks caused by excessive pressure

Break tanks are commonly used in residential, commercial, and industrial plumbing systems, particularly in areas with high water pressure or where water hammer effects are a concern.

How to Calculate Break Tank Size

Calculating the appropriate break tank size involves several factors, including the plumbing system's design, water pressure, and potential pressure surges. Here's a step-by-step guide to determining the right size:

1. Determine the total volume of water in the system
2. Calculate the potential pressure surge volume
3. Consider the system's water pressure and flow rate
4. Account for any additional safety margins
5. Use the break tank sizing formula to determine the required capacity

The result will give you the minimum required capacity for your break tank, ensuring it can handle the expected pressure fluctuations without compromising system performance.

Factors Affecting Break Tank Sizing

Several factors influence the proper sizing of a break tank. Understanding these factors is essential for accurate calculations and optimal system performance:

1. System Water Volume

The total volume of water in the plumbing system is a primary consideration. Larger systems with more pipes and fixtures will require proportionally larger break tanks to accommodate pressure surges.

2. Water Pressure

The water pressure in the system affects the potential for pressure surges. Higher water pressure systems may require larger break tanks to handle the increased force of pressure changes.

3. Pipe Size and Material

The size and material of pipes in the system impact how pressure surges propagate. Larger pipes and certain materials may require different break tank sizing approaches.

4. System Layout and Design

The physical layout of the plumbing system, including the arrangement of pipes and fixtures, affects how pressure surges are distributed. Complex systems may require more sophisticated break tank sizing calculations.

5. Potential Pressure Surges

Different plumbing operations can create varying levels of pressure surges. Understanding the specific operations in your system helps determine the appropriate break tank size.

Break Tank Sizing Formula

The standard formula for calculating break tank size is based on the system's water volume and potential pressure surge volume. The formula is:

Where:

• System Water Volume - Total volume of water in the plumbing system (gallons)
• Pressure Surge Factor - A factor that accounts for potential pressure surges (typically 0.1 to 0.3)
• Safety Margin - Additional capacity to ensure the break tank can handle unexpected surges (typically 10-20% of the calculated volume)

This formula provides a conservative estimate that ensures the break tank can handle the expected pressure fluctuations while maintaining system integrity.

Example Calculation

Let's walk through an example to illustrate how to calculate break tank size. Suppose you have a residential plumbing system with the following characteristics:

• Total system water volume: 500 gallons
• Pressure surge factor: 0.2
• Safety margin: 15%

Using the break tank sizing formula:

Based on this calculation, you would need a break tank with a minimum capacity of 175 gallons to properly handle pressure surges in this system.

This example demonstrates how the formula accounts for both the potential pressure surges and the need for additional safety capacity to ensure reliable system performance.