High degassing rate and adjustable trigger pressure for sophisticated battery systems
Freudenberg Sealing Technologies is expanding its DIAvent® product family with the DIAvent® maxFlow degassing element for lithium-ion batteries in vehicles. Once it reaches an individually configurable trigger pressure, the valve opens instantly and fully. Following its debut at The Battery Show North America 2025, the complete technical specifications are now available.
As energy densities in modern vehicle batteries continue to rise, so do the gas volumes that require quick and controlled venting from the battery housing in the event of thermal runaway in individual cells. Existing solutions increasingly reach their limits: While overpressure causes conventional burst disks to open, it is not possible to close them again afterward. In addition, there is no way to precisely adjust the opening pressure of a burst disk, nor is it possible to perform nondestructive testing after the production or installation on the battery.
Metal spring instead of rubber umbrella
The DIAvent® maxFlow is based on an entirely new operating principle within the DIAvent® family: Instead of a rubber umbrella, the valve uses a profiled metal spring. As soon as the defined trigger pressure is reached, it opens suddenly and completely – not gradually, as in previous generations. This lets hot gases vent significantly faster, which greatly reduces the risk of further escalation within the battery system. The full flow rate is already reached close to the opening threshold. After the pressure is released, the spring autonomously closes the opening again, preventing oxygen from flowing into the battery. This also protects rescue and emergency personnel, as the battery stays closed after the degassing.
Performance data and technical specifications
The emergency degassing rate of the DIAvent® maxFlow is more than 190 liters per second at a differential pressure of 300 mbar – this is an increase by a factor of 2.5 compared with the DIAvent® HighFlow. The activation pressure can be freely adjusted between 50 and 200 mbar, with low tolerance. Even with these performance values, the installation height is very low at just 12.1 millimeters and the overall dimensions are a compact 86 × 86 × 12 millimeters. Each valve meets comprehensive protection classes (up to IPX9K and IP6KX), is certified according to UL94 V0, and is 100 percent inspected before delivery. A universal M6 bolt can be used for fastening; other options include clip or bayonet solutions. An integrated PIP seal compensates for unevenness of up to 0.2 millimeters in the housing.
As the system is reversible, customers can inspect the fully installed battery pack non-destructively during end-of-line testing – a major quality advantage compared to burst disks.
“With the DIAvent® maxFlow, we have addressed the disadvantages of previous venting solutions with a single product. Now we can significantly increase both safety and flexibility in battery development,” says Daniel Uhl, Head of Product Management at Freudenberg Sealing Technologies.
For the first time, Freudenberg Sealing Technologies is combining maximum flow rate, adjustable trigger pressure and autonomous resealing in a single degassing valve.
More information is available at: www.fst.com/products/special-sealing-products/diavent
