Flat Vacuum Safety Disc
Model: ZD-006 (Breather/Vacuum Relief Type)
Material: Typically SS304/316, PTFE-coated options.
Design: Flat membrane with cruciform or star-shaped score lines.
Function: Protects against vacuum collapse (primary) and slight overpressure.
Cracking Pressure: Very low, often from a few mbar to 100 mbar differential.
Typical Use: Tank and vessel protection during emptying, cleaning, or temperature drops.
Overview
Tanks and vessels are at risk not only from overpressure but also from vacuum collapse during pumping out or cooling. The flat vacuum safety disc is a lightweight, economical device designed to act as a pressure/vacuum breather. It ruptures at a very low differential pressure (vacuum inside) to admit air and prevent collapse. It can also relieve minor overpressure. It is commonly used on storage tanks, reactors, and mobile containers.
Features & Benefits
Dual-Function Protection: Can be specified for vacuum relief only or vacuum/low overpressure relief.
Low Cracking Pressure: Sensitive to very small pressure differentials, providing early protection.
Lightweight & Compact: Simple design requires minimal space and weight on vessel tops.
Cost-Effective Breather: An affordable alternative to more complex pressure/vacuum relief valves for many applications.
Essential for Tank Safety
Prevents the catastrophic implosion of tanks during unintended vacuum conditions, a often overlooked but critical hazard.
How It Works
The flat disc is clamped between flanges. Under vacuum (negative differential pressure), atmospheric pressure pushes on the disc. When the differential exceeds the disc's rating, it bursts open along its pre-weakened slots, allowing air to enter and equalize pressure. For overpressure relief, the process is reversed.
Specifications (Descriptive)
Sizes typically from DN50 to DN300. Operating differentials are very low: e.g., 25 mbar (1" H₂O), 50 mbar, 100 mbar. They are not for high-pressure service. Common materials are SS304 or SS316. For corrosive atmospheres, a PTFE coating is applied. They are installed with a weather hood or flame arrester if venting to atmosphere.
Accessories
Weather Protection Hood (Rain Cap)
Flame Arrester Element (for venting flammable vapors)
Dust Screen
Replacement Disc Kits
Q&A
Q: Can this replace a pressure/vacuum relief valve (PVRV)?
A: For simple applications where occasional, non-frequent relief is expected and where the medium is air, it can be a lower-cost, maintenance-free alternative. A PVRV resets itself and is better for frequent cycling.
Q: What happens after it bursts?
A: It is a single-use device. After activation, it must be replaced. The vessel is exposed to atmosphere until replacement.
Q: How is it sized?
A: Sizing is based on the required flow area to admit air fast enough to prevent vacuum damage during the maximum expected emptying or cooling rate, per standards like API 2000.
About ZD Safety
We supply essential tank protection equipment. Our flat vacuum discs are a simple, reliable final safeguard against vacuum collapse, crucial for tank farm and process vessel integrity
