EN 250-2014 pdf download.Respiratory equipment – Open-circuit self-contained compressed air diving apparatus – Requirements, testing and marking.
If a demand regulator incorporates adjustable sensitivity controls then the demand valve shall be tested at both the maximum and minimum performance positions. Demand valves which incorporate a dive/pre-dive control shall be tested with the control set to dive position. Air is supplied to the medium pressure side of the reducer and the air supply pressure is gradually increased: the medium pressure required to create a continuous flow of 400 I/mm through the demand valve. Under these conditions, a breathing simulator test is conducted on the complete apparatus including the facepiece and the respiratory pressure is measured at the appropriate pressure sample point.
6.7 Demand regulator
6.7.1 General
The dynamic performance of the apparatus shall be determined from the pressure-volume diagram, generated by plotting the respiratory pressure against the displaced volume. It shall be measured at a pressure of 6 bar absolute using a breathing simulator set to provide a sinusoidal minute volume of 62,5 I/mm (25 cycles/mm, 2.5 I/stroke). The variation in frequency and amplitude shall not deviate from the set value by more than ± 3 %. The test duration shall be such as to obtain steady-state performance.
Throughout these tests, with the exception of the test relating to low temperature, the demand regulator shall be immersed in water at a temperature of io_9 °C and the demand valve shall be rigged as though the diver’s head is in the upright position to a depth of at least 0,2 m to preclude surface effects.
Testing shall be carried out with the apparatus supplied with high pressure air at the rated working pressure of the regulator as specified by the manufacturer and repeated at 50 bar.
This test shall be performed in water, at I bar pressure by checking while breathing at 62,5 1/mm (25 cycles/mm, 2,5 I/stroke) for 5 mm. The test shall be conducted with a 14 I cylinder and shall commence at the rated working pressure of the regulator.
Where the demand regulator is tested separately it shall be supplied by a device (which may be a cylinder valve) which causes a pressure drop of 9 bar to 10 bar when tested in accordance with 6.9.
6.7.2 Cold water performance
Apparatus and sub-assemblies intended for use in water temperatures below 10 C shall be immersed and tested as ready-for-use apparatus in fresh water at a water temperature of 4 °C at a depth of at least 0,2 m for 5 mm at 6 bar absolute pressure. The demand valve shall be rigged as though the diver’s head were in both the upright and the horizontal face down (swimming) position respectively.
The air exhaled by the breathing simulator shall be heated and humidified. The air temperature shall be (28 ± 2) C and the relative humidity greater than 90 % throughout the test when measured at the interface with the demand valve.
The cylinder(s) used for the test of the demand regulator shall have an internal volume of 14 I. They shall be charged to the maximum rated working pressure of the regulator.
If the rated worling pressure of the regulator is less than 200 bar, the cylinder(s) when charged to the rated working pressure of the pressure reducer shall contain sufficient air to complete the test and shall not be discharged to less than 50 bar.
The complete self-contained apparatus with any external gas supply isolated shall be immersed in the cold water for a period of 10 mm prior to starting the test. The complete self-contained apparatus shall stay immersed during the test.
6.8 Exhalation valve
The following tests shall be carried out in the following sequence:
a) The exhalation valve shall be subjected to a constant flow of 300 11mm for a period of 1 mm.
b) The test shall be carried out using a demand valve with wetted exhalation valve and with the medium pressure supply port blanked: A static negative pressure of 80 mbar is applied at the demand valve without the facepiece for a period of 10 s.
C) The exalation valve shall then be tested to verify the leakage at a negative pressure of 7 mbar.EN 250-2014 pdf download.