FRL™ Reverse Buckling Rupture Disk

Performance Features

  • Liquid service
  • Designed for non-fragmentation
  • Withstands full vacuum
  • Suitable for operating ratio to 95% of the minimum burst pressure
  • Damage safety ratio of 1 or less. A damaged disk will burst at its marked burst pressure or lower
  • Recommended for safety relief valve isolation
  • Optional fluoropolymer liner on the process or downstream side of the disk
  • Standard 0% MDR; optional -5% and -10% MDR
  • BS&B proprietary technology

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  • Sizes & Pressures
  • Burst Tolerance
  • Safety Heads & Sensors
  • Accessories
  • Documentation

Sizes & Pressures

FRL™ Disk Specifications Minimum/Maximum Pressure with Rating at 72° (22°C)

Disk Size Burst Pressure
psig barg
in mm min max min max
1 25 13.5 (36)* 150 0.93 (2.48)* 10.34
1.5 40 11.5 (16)* 70 0.79 (1.10)* 4.83
2 50 11.5 (14)* 50 0.79 (0.79)* 3.45

* Pressures in parenthesis are with fluoropolymer liners

Note: Hastelloy® is a trademark of Haynes International Inc. Monel® and Inconel® are registered trademarks of Special Metals Corporation and Its subsidiaries. Available materials: 316 Stainless Steel, Nickel (alloy 200), Inconel (alloy 600), and Monel (alloy 400). Other materials available upon request.

Burst Tolerance

Marked Burst Pressure Burst Tolerance
≤ 40 psig (2.76 barg) ± 2 psig (0.138 barg)
> 40 psig (2.76 barg) ± 5%


BS&B supplies many of the Accessories required to safely and conveniently install our overpressure relief devices and complementary products. Through our professional team and global network of sales engineers and procurement personnel, we are able to provide the highest quality accessory products to meet your installation requirements.

Saf-T-Change Quick Disk Replacement (QDR)

After activation, the replacement disk is quickly slid into place. Saving hours of lost production due to blown rupture disks.

Tell-Tale Assemblies & Excess Flow Valves/Gauges

A gauge tap in the outlet flange of the safety head may be considered when the safety head is installed in a vertical position.

Spare Safety Heads & Cap Screws


When activated, the jackscrews effectively separate the flanges, providing adequate clearance to remove or insert a safety head and external gaskets.

Lifting Lug Eye Bolts

Eye bolts are recommended when weight and/or accessibility is a factor in lifting safety heads.

Baffle Plate

When a safety head is free-vented to atmosphere, a baffle plate may be considered to disperse overpressure and absorb recoil.

Product Literature

Sta-Saf System
Burst Alert Sensors
Saf-T-Change™ QDR Rupture Disk Replacement System
Detec Saf Alarm System - Burst Disk Monitor


Sta-Saf™ System Installation Instructions