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Operation of a Hydrostatic Release Unit
Overview
[edit]A hydrostatic release unit or HRU is a pressure activated mechanism designed to automatically deploy when certain conditions are met. In the marine environment this occurs when submerged to a maximum depth of four meters. The pressure of the water against a diaphragm within the sealed casing causes a plastic pin to be cut thereby releasing the containment bracket casing, allowing the EPIRB to float free.
Description
[edit]A hydrostatic release unit is a type of pressure activated release mechanism(ARM). Some common characteristics of HRUs are:
- Water pressure sensitive at depths not to exceed four meters or less than two meters
- Single use only, require replacement if activated
- Cannot be serviced; only replaced
- Waterproof; sealed against moisture and tampering
- Must be labeled with expiration date
- Expiration date is two years from month of installation applies to unit and rod
Regulations and Technical Specifications Governing EPIRB, Hydrostatic Release Devices
[edit]- ISO 15734
- Solas 74.95
- CFR title 46 Vol 6 Section 160.062
- USCG 160.162[1]
- Corrosion Resistance Test
- Temperature Tests
- Submergence and Manual Release Test
- Strength Tests
- Technical Tests on the Membrane
- Performance Test
Operation Video
[edit]Although this demonstrates a HRU for a life raft, the EPIRB HRU works on the same principle.
Operation of a Hydrostatic Release Unit
References
[edit]- Notes