BS 746:2014 pdf free.Specification for gas meter unions and adaptors.
BS 746 Leave at room temperature of (20 +3) °C for a period of 1 h, then place the assembly in an environmental chamber at a temperature of (60 +3) °C and leave for a period of not less than 4 h. Remove the assembly from the environmental chamber and leave the assembly at room temperature of (20 +3) °C for a period of 2h. Leave at room temperature of (20 +3) °C for a period of 1 h then place the assembly in an environmental chamber at a temperature of (-20 +3)。C and leave for a period of not less than 4 h. Increase the temperature within the chamber to (60 +3) °C， and once a temperature of (60 +3) °C is reached maintain the temperature for a period of not less than 4 h. Remove the assembly from the environmental chamber; leave the assembly at room temperature of (20+3)°Cforaperiodof2h. NOTE If any of the groups are split into subgroups, due for example to the environmental chamber being unable to accommodate 15 samples, it is necessary to be able to show that the test conditions were the same for each subgroup.4.2.2.2.4 After each assembly has undergone the environmental conditioning specified in 4.2.2.2.3, set the pressure in the assembly to 75 mbar. lsolate the pressure supply, then observe a 1 min temperature stabilization. Take the pressure (P1) within the assembly and observe a test period of 2 min. Following this, take a second pressure reading (P2). Calculate the rate of leakage during the test period using the total volume of the assembly under test and the two
pressures P1 and P2. The gauge used shall be a digital pressure gauge with a resolution of 2 dcp.NOTE 1 When undertaking the gas tightness test, care has to be taken not to affect
the gas tightness of the assembly, e.g. avoid tightening against it or otherwise clamping the joint.NOTE 2 It is not necessary to test all groups simultaneously, only that 60 samples be
tested in four groups.BS 746 pdf downlaod.