AS 4758.3:2015 pdf download.Lifejackets Part 3: Test methods.
SECTION 4 BUOYANCY
4.1 PRINCIPLE
The buoyancy of a lifejacket is determined using Archimedes’s Principle by measuring the difference in weight of a weighted cage suspended in water and again with lifejacket placed in the cage. The loss of buoyancy is determined by comparing the original buoyancy and the buoyancy after the lifejacket has been submerged for 24 h.
4.2 APPARATUS
The following apparatus is required:
(a) A weighted cage of sufficient size to contain the lifejacket and with a mass in kilograms greater than 1.1 times the expected buoyancy of the lifejacket.
(b) An open tank containing sufficient fresh water with a temperature not greater than 22°C to immerse the cage 100 mm to 150 mm below the surface of the bottom and sides.
(c) A calibrated load cell or balance to measure the weight of the lifejacket.
4.3 PROCEDURE
The procedure shall be as follows: (a) Suspend the weighted cage from load cell or balance 1 00 mm to 1 50 mm below the surface of the water in the tank.
(b) Measure and record the weight, 1111. (c) Remove the weighted cage from the water. (d) Place the lifejacket in the cage and ensure that the following conditions are observed: (I) For a lifejacket containing inherently buoyant material contained in pockets formed by an outer covering that is impervious to water, slit the outer fabric, remove the buoyancy material, place all components of the lifejacket in a muslin bag and insert the bag and contents in the cage.
(ii) For an inflatable lifejacket, inflate the lifejacket with the supplied cylinder, wait I mm, and place in the cage. (e) Suspend the weighted cage containing the lifejacket from the load cell or balance 100 mm to 150 mm below the surface of the water in the tank and ensure that air is not entrapped between any of components. (f) After 24 ±0.5 h measure and record the weight, m2 and remove the assembly from the tank.
(g) Calculate the initial buoyancy from the following equation: B1= 9.8 (1111 — p12) where B1 = buoyancy, in newtons m1= weight of submerged empty cage, in kilograms m2= weight of submerged cage containing lifejacket, in kilograms.
7.1 GENERAL
In-water performance testing shall be conducted in front of an observer, as described in Clause 7.2.1, using subjects, as described in Clause 7.2.2.
NOTE: The water in the pool should be treated as necessary for hygienic purposes.
Lifejackets shall readily fit various sizes of adults, both ordinary and heavily clad. A lifejacket designed to be worn inside-out shall be tested in all configurations.
Where it is required to test while wearing ordinary clothing, such clothing is defined as follows:
(a) Underwear (short sleeved, short legged).
(b) Shirt (long sleeved).
(c) Trousers (not woollen).
(d) Athletics shoes, if the device is required to be donned over the foot and leg.
Heavy weather clothing is defined as ordinary clothing with the addition of a wet weather jacket and gloves.
Test subjects shall be generally informed of the methods and intent of the in-water performance tests, but should have no knowledge of the specific lifejacket being tested. The subjects shall be in suitable health to physically perform the tests. The principles of the Declaration of Helsinki 1976 (as amended) are to be considered in so far as applicable.
The tests may be modified for child test subjects under 12 years of age who are not water adapted, so as to ensure their safety and co-operation. When assessing such children’s sizes, the observer can make greater use of subjective indicators, as self-righting and jumping can be hazardous and more subjective when applied to small children. The position in the water and support afforded may be useful indicators. AS 4758.3 pdf download.