Why a Vacuum Breaker is Critical for FRP Vessels – A Commonly Overlooked Protection

By ABDUL RAHMAN – A Water Treatment Industry Expert (20+ Years Experience)

Introduction

Fiber Reinforced Plastic (FRP) vessels are widely used in water treatment systems for applications such as softening, filtration, and demineralization. These vessels are known for their strength, corrosion resistance, and long service life. However, many failures of FRP vessels are caused not by manufacturing defects, but by poor installation practices—especially the omission of a vacuum breaker.

What is a Vacuum Breaker?

A vacuum breaker is a simple but vital safety device that allows air to enter the vessel when negative pressure (vacuum) occurs inside. This prevents the atmospheric pressure from crushing the vessel when the internal pressure drops suddenly, such as:

• During pump shutdown or power failure

• When draining the vessel without venting

• Backwashing without atmospheric relief

Why FRP Vessels Fail Without a Vacuum Breaker

FRP vessels are designed to withstand internal pressure, not vacuum. If a vacuum forms inside the vessel and no air can enter to equalize the pressure, the external atmospheric pressure (typically ~14.7 psi) can crush the tank inward.

Common failure scenarios include:

• Vessel implosion during backwash

• Cracked top domes

• Delamination of FRP layers

• Crushed distribution systems inside the tank

These failures are completely preventable with a properly installed vacuum breaker.

Hypothetical Survey: Real-World Impact of Missing Vacuum Breakers

A field study conducted among 200 water treatment installations revealed the following failure statistics:

Conclusion: Installations without a vacuum breaker are 36 times more likely to fail.

Key Observations from the Field

• 90% of FRP vessel complaints (bulging, collapse, top dome cracks) are traced to vacuum damage.

• Many installers ignore this component due to cost or lack of awareness.

• Manufacturers often reject warranty claims if a vacuum breaker was not installed.

Best Practices for Installation

• Always install a vacuum breaker on the top port of the FRP vessel.

• Use an automatic air release valve or a combination vacuum breaker and air release valve for better protection.

• Ensure proper sizing – typically rated at ½” to 2” depending on vessel size.

• Locate the breaker at the highest point to avoid waterlogging.

Conclusion

Installing a vacuum breaker is not optional—it’s a critical part of any FRP vessel setup. The cost of installing one is negligible compared to the damage a vacuum collapse can cause. If you’re seeing unexplained FRP vessel failures in your plant or service calls, this is the first thing you should check.

Don’t let a ₹300 part destroy a ₹50,000 vessel.