User:12thave/sandbox

Operation of a Hydrostatic Release Unit

Overview
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
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

 * ISO 15734
 * Solas 74.95
 * CFR title 46 Vol 6 Section 160.062
 * USCG 160.162


 * Corrosion Resistance Test
 * Temperature Tests
 * Submergence and Manual Release Test
 * Strength Tests
 * Technical Tests on the Membrane
 * Performance Test

Operation Video
Although this demonstrates a HRU for a life raft, the EPIRB HRU works on the same principle.

Operation of a Hydrostatic Release Unit