HRU stands for Hydrosatic Release Unit. This is a important and mandatory equipment for a liferaft in a commercial and passenger vessel. The main purpose of this equipment is to launch the liferaft automatically when a ship sank and the liferaft unable to be launched manually. HRU is also used in launching the EPIRB automatically.
One of the leaders in HRU manufacturer is Hammar, a Swedish company based in Gotenburg. The HRU the company manufactured is called H2O. The packaging is compact and the box is of good quality, something you expect from a Swedish company. The box had multiple languages on it.
Inisde the box is 1 unit of HRU unit itself and a simple installation manual. The installation manual had self adhensive features on it and can be posted anywhere onboard the ship. Nice feature.
The Hammar H20 is a hydrostatic release unit that fits liferafts of all shapes and sizes. It's made of glassfibre reinforced nylon, which means that it won't rust. The Hammar H20 needs no annual service, maintenance or spare parts (virtually maintenance free). Simply install a new one every two years and dispose of the old one. Keeping the environment in mind, the old unit is 97% recyclable ( I wonder where to recycle it).
Simple handling procedures mean that storage costs are also kept down to a minimum. With the H20, installation is both easier and quicker, greatly reducing customers downtime ashore.
Compared with conventional release units, the Hammar H20 offers savings of up to 50% over a 10 year period. The Hammar H20 is now the biggest selling hydrostatic release unit in the world. Its safe, reliable and simple design has earned it more world-wide approvals than any other unit. In fact, it's a small wonder!
Fitting of the HRU on the liferaft.
The expiry date of the HRU should be marked. Basically just carved off the sticker on it. The expiry date should be 2 years after you install it. I personally think the lifespan is too short. It would be better if it can last up to 3 years or so.
The HRU had a useful feature as it has a weak link connector, which is coloured red (which is an improvement from its previous HRU product). The liferaft painter must be secured to the weak link or else the liferaft won't able to launch when the ship sank. Many ship crew did not realize this or connect the liferaft painter wrongly.
White strong rope of Hammar H20 secured to deck or liferaft cradle and attached to liferaft lashing with a sliphook. Liferaft painterline shackled to weak-link and around strong white rope.
If the ship sinks, the water pressure will, within 4 metres, activate the sharp knife which cuts the strong rope and the liferaft will float free.
As the ship sinks, the liferaft painterline will be stretched and the liferaft starts to inflate.
Red weak link breaks and survivors can board the inflated liferaft.