Reverse-Acting Rupture Disc
Model: ZD-002 (Crocodile Tooth Shear Type)
Material: Disc: 316L / Inconel 625 / Monel. Holder: Carbon Steel.
Burst Range: 1 barg to 15 barg.
Operating Ratio: Up to 90% of rated burst pressure.
Key Feature: Fragmentation-free opening. Excellent fatigue resistance.
Vacuum Service: Capable of full vacuum without support.
Typical Use: Isolation of safety valves, gaseous media.
Overview
The reverse-acting rupture disc is engineered for reliability in cyclic pressure services. Its convex dome faces away from the pressure source. Upon reaching the set pressure, the disc buckles inward (reverses) and is cleanly sheared by a peripheral knife ring, creating a full, unobstructed opening without generating fragments. This makes it ideal for protecting sensitive downstream equipment or for series installation with safety valves, where disc debris could cause damage or blockage.
Features & Benefits
No Fragments: The sheared disc center is retained, preventing debris from entering downstream piping.
High Fatigue Life: Can withstand a high number of pressure cycles (often up to 90% of burst pressure), perfect for pulsating systems.
Full Vacuum Rating: Inherently resistant to collapse under vacuum conditions, eliminating the need for costly vacuum supports.
High Operating Ratio: Allows systems to run closer to the burst pressure, optimizing process windows.
Superior for Safety Valve Isolation
When installed under a safety valve, it forms a leak-tight seal, isolating the valve from corrosive, polymerizing, or fouling process media. This extends valve service life and permits in-line maintenance.
How It Works
Under pressure, the reverse dome is in compression. At the burst point, it suddenly buckles (snaps) inward. This reversal brings the disc into contact with sharp knife blades integrated into the holder, which shear the disc open around its circumference. The central piece is captured.
Specifications (Descriptive)
Available in sizes from DN20 to DN300. For DN50, common burst pressures range from 2-10 barg. DN150 typically handles 1-6 barg. Materials like Nickel 200 suit lower pressures (~1.4-12 barg for DN32), while Inconel 625 extends range and corrosion resistance (~3.5-15 barg for DN32). Stainless steel (316L) offers a balance, with DN25 ranging 5-15 barg. Maximum temperature ratings vary by material: SS316 up to 400°C, Inconel up to 480°C.
Accessories
Teflon (PTFE) Coating or Lining
Burst Indicator (Mechanical Pin or Electric Switch)
Rupture Disc Alarm Modules
Q&A
Q: Why choose reverse-acting over forward-acting?
A: Choose it for applications with pressure cycling, where no fragments are allowed downstream (e.g., before a safety valve or compressor inlet), or when full vacuum capability is needed without extra supports.
Q: What does "operating at 90% of burst pressure" mean?
A: It means you can safely run your process at a steady pressure up to 90% of the disc's rated burst pressure without significantly reducing its service life or causing premature failure, which is excellent for high operating ratio systems.
Q: Can it handle liquid service?
A: It is primarily designed for gas or vapor service. The buckling action requires compressibility. For liquids, a forward-acting or composite disc is usually recommended.
About ZD Safety
ZD Safety specializes in advanced pressure relief solutions. Our reverse-acting discs are precision-manufactured and 100% tested to ensure performance where reliability is non-negotiable. Certified to ISO 9001, ASME, and PED standards.
