Bi-Directional Overdriven / Unstable Detonation Flame Arresters – UL / ULC / FM / USCG

25000 / 26000

Gas Groups:
25000 – D | IIA
26000 – D, C | IIA, IIB3 

Protectoseal Series 25000 and 26000 Detonation Flame Arresters are specifically designed to withstand confined deflagrations, stable detonations and overdriven (unstable) detonations. These arresters are bi-directional and are designed to withstand and arrest the high velocity and high pressure flame fronts that may develop in long or complex piping runs encountered in vapor recovery or manifolded tank systems. These can be mounted in any location in a piping system so long as initial temperature and initial pressure guidelines are followed. 


  • Certified flow curves validating flow characteristics of unit
  • Bi-directional design stops a flame approaching from either direction in a piping system
  • Crimped metal arrester element minimizes pressure drops and reduces overall weight
  • Straight through flow pattern minimizes arrester element fouling and simplifies the cleaning process
  • Removable and interchangeable arrester element facilitates ease of inspection and maintenance
  • High strength, welded steel housing hydrostatically tested at 475 PSIG
  • Pressure retaining housing components are welded in accordance with ASME Pressure Vessel Code, Section IX requirements
  • Sizes: 25000 – 2” through 18”26000 – 2” through 12” 
  • Flanged to mate with standard flanged 150# ANSI 
  • Maximum Initial Pressure: 25000 – 17.2  17.7 PSIA*26000 – 15.9 – 19.7 PSIA* (*varies based size, see spec sheet for details) 
  • Maximum Initial Temperature: 60 C (140 F) 
  • Housing Configuration: Concentric 
  • Materials: Carbon SteelStainless Steel and Alloy C276 
  • Gas Groups25000 – NEC Group D | IEC Explosion Group IIA26000 – NEC Groups D, C | IEC / ISO Explosion Groups IIA, IIB3 
  • Testing and Certifications25000 – UL, ULC & USCG; 26000 – FM, USCG (check spec sheet for various sizes)  
  • For arresters that meet the latest ATEX Directiverefer to Series 25000E / 35000ESeries 26000E / 36000E  
  • Connections: Other drilling patterns available upon request. DIN PN16 connections available in the Series 25000E / 35000E and Series 26000E / 36000E.
  • Materials certifications for castings
  • Connections for drains, pressure taps or temperature probes available upon request