Explosion Proof Pressure Relief Vent Bolt Burst Disc Breathable Membrane Battery Pack

Product Overview

This explosion-proof pressure relief vent bolt combines a breathable ePTFE membrane with an integrated burst disc to provide dual-function protection for sealed battery packs. Under normal conditions, it equalizes pressure; during a thermal runaway event, the burst disc ruptures at a precise set pressure to prevent explosive housing rupture. The all-stainless steel construction and ATEX-certification compatibility make it suitable for the most safety-critical energy storage applications.

Cause

Lithium-ion battery packs store massive energy. If a cell fails and vents flammable gas, the internal pressure rises exponentially. Without a dedicated relief mechanism, the pack housing can explode, propelling shrapnel and releasing toxic fumes. Standard breather vents with only a membrane cannot vent the high instantaneous flow rates required during such an event.

Solution

This vent bolt incorporates a calibrated burst disc that opens within milliseconds of exceeding the set pressure, creating a large-area vent path for gases and particulates. The ePTFE membrane remains functional before and after the burst event, providing continuous IP67 protection. This dual-action design ensures daily pressure balance without compromising the critical emergency venting function.

Specifications

• Thread: M25 x 1.5

• Body: 316L stainless steel

• Membrane: ePTFE with burst disc

• Burst pressure tolerance: ±10%

• Normal airflow: 600 ml/min @ 70 mbar

• IP rating (post-burst): IP66

• Certification: Designed to IEC 60079

Application

Mandatory for high-voltage EV battery packs, stationary utility-scale energy storage systems, underwater ROV battery pods, and aviation battery containers. Also used in explosion-proof junction boxes for chemical and mining industries.

How It Works

During normal charge/discharge cycles, the ePTFE membrane handles gradual pressure changes. If a cell goes into thermal runaway, pressure rises past the burst disc’s threshold, causing it to rupture and create a large exhaust orifice. Hot gases escape in a controlled direction. The remaining membrane continues to block water and dust, preventing extinguishing water from entering and potentially causing short circuits.

How To Choose

Consult your pack’s structural analysis to determine the maximum allowable working pressure and set the burst disc 20% below that value. Consider the venting gas composition; stainless steel 316L resists acidic gases. Ensure the thread and sealing surface are compatible with your housing’s weld boss or threaded insert.

FAQ

Q: Does the burst disc need periodic replacement?

A: No, it is a passive component. However, after any venting event, the entire vent bolt assembly must be replaced immediately.

Q: How do I validate the burst pressure?

A: Random samples from the batch should be tested on a pressure ramp tester. Certification documents are provided by the manufacturer.

Q: Can it be installed in any orientation?

A: It must be oriented so that vented gases are directed away from personnel and sensitive components. Follow the directional arrows on the body.