Product: Hydrostatic Release Unit (HRU)
Brand: Hammar
Model: H20 (common model)
Application: Liferaft / EPIRB automatic release system
 
Function
A Hydrostatic Release Unit automatically releases a liferaft or EPIRB when a vessel sinks. It works using water pressure. When the ship submerges, the pressure activates a cutter inside the unit that releases the securing rope so the equipment can float to the surface.
 
Main Specifications
Activation Depth: 1.5 – 4 meters underwater
Breaking Strength (White Rope): approx. 15 kN
Weak Link Breaking Strength: about 2.2 ± 0.4 kN
Material: Glass-fiber reinforced nylon (corrosion resistant)
Service Life: typically 2 years (disposable type)
Maintenance: No annual service required
Certification: SOLAS / MED / USCG (depending model)
 
Water pressure pushes a diaphragm inside the unit, releasing a spring-loaded blade that cuts the securing rope, allowing the liferaft to float free and inflate automatically.