11 Hydrostatic Release Units

 Two samples of hydrostatic release units should be given a visual and dimensional examination. If the devices conform with the manufacturer's drawings and specifications, they should be accepted and assembled for further testing under the technical and performance tests as prescribed in 11.2 and 11.3.

 Each hydrostatic release unit should undergo all the following technical tests. No parts should be renewed or repaired between the tests. The tests should be conducted in the following sequence:

• .1 Corrosion resistance test

  A hydrostatic release unit should be exposed to a salt water spray test (5% natrium chloride solution) at a temperature of 35 ± 3°C for 160 h without interruption. After completion of the test the hydrostatic release unit should show no corrosion which could affect its efficient functioning and should then be subjected to the following tests after which it should continue to function efficiently.

• .2 Temperature tests

  The hydrostatic release units should then be subjected to the temperature cycling prescribed in 1.2.1. Following temperature cycling as prescribed in 1.2.1, one hydrostatic release unit should be taken from a stowage temperature of -30°C and should then operate in seawater at a temperature of -1°C. The other hydrostatic release unit should be taken from a stowage temperature of +65°C, and should then operate in seawater at a temperature of +30°C.

• .3 Submergence and manual release tests

  The hydrostatic release unit should then be tested by applying a buoyant load equal to its designed capacity while the device is submerged in water or in a water-filled pressure testing tank. It should release at a depth of not more than 4 m. On completion of these tests and resetting, the hydrostatic release unit should be capable of being released manually if it is designed to allow manual release of the unit. It should then be opened for inspection and should show no significant signs of corrosion or degradation.

• .4 Strength test

  After reassembly the hydrostatic release unit, if forming part of the painter system, should be subjected to a tensile test of at least 10 kN for a period of 30 min. If the release unit is to be fitted to a liferaft for more than 25 persons it should be subjected to a tensile test of at least 15 kN. After the tensile test the unit, if designed to allow manual release should then be capable of being operated manually.

• .5 Technical tests on the membrane

  The following test should be carried out on the membrane:

• .5.1 Test of resistance to cold

  Number of specimens	2 membranes
  Temperature	-30°C
  Exposure time	30 min
  Flex testing	180° with both inside and outside stretched.
  Requirements:	The membranes should show no visible cracking.

• .5.2 Test of resistance to heat

  Number of specimens	2 membranes
  Temperature	+65°C
  Exposure time	7 days
  Requirements:	The membranes should show no visible cracking.

• .5.3 Test for surface resistance to oil

  Number of specimens	2 membranes
  Temperature	+18°C to +20°C
  Type of oil	A mineral oil meeting the following requirements:
  	Aniline point: 120 ± 5°C
  	Flashpoint: minimum 240°C
  	Viscosity: 10-25 cSt at 99.0°C
  The following oils may be used:	IRM 901 IRM 905 ISO Oil No. 1
  Testing period	3 h on each side
  Requirements:	The material should show no deterioration.

• .5.4 Two membranes should be immersed for 7 days in 5% natrium chloride solution:

  Test temperature	+18°C to +20°C
  Requirements:	The material should show no deterioration.

• .5.5 Resistance to detergents

  Two membranes should be immersed for 7 days in detergents commonly used on board ship:

  Test temperature	+18°C to +20°C
  Requirements: The membranes should show no signs of deterioration.

• .6 Solar radiation test

  One unit should be subjected to a solar radiation test to paragraph 8.10 of IEC 60945:2002.

  Note The solar radiation test may be waived where the manufacturer is able to produce evidence that the materials employed will satisfy the test, i.e., UV stabilized.

  11.3.1 This test should be performed using the smallest and the largest liferafts with which the hydrostatic release unit may be used. If the occupant range between the smallest and largest liferaft exceeds 25 persons, then the intermediate size liferaft should also be tested. The liferaft should be placed horizontally on a rack or platform of sufficient weight to submerge the liferaft. The hydrostatic release unit and painter should be installed as aboard ship.

  11.3.2 The following tests should be carried out in a suitable depth of water. The platform on which the liferaft is mounted should be lowered into the water as follows:

• .1 horizontal;

• .2 tilted 45° and then 100° with the hydrostatic release unit at the upper side;

• .3 tilted 45° and then 100° with the hydrostatic release unit at the lower side; and

• .4 vertically.

 Under these conditions the hydrostatic release unit should release the liferaft at a depth of less than 4 m.