Over-pressure and under-pressure shut-off devices
AS 4632-2020 pdf download.Over-pressure and under-pressure shut-off devices.
3.6 Repeatability
3.6.1 Tripping and resetting cycles — tinder-pressure shut-off devices
An under-pressure shut-off device shall operate within ± 5 % of the average of 6 cycles of tripping and resetting at the minimum set pressure.
Conformance shall be assessed by testing with the method in Clause 8.14.
3.6.2 Tripping and resetting cycles — Over-pressure shut-off devices
An over-pressure shut-off device shall operate within ± 5 % of the average of 6 cycles of tripping and resetting at the maximum set pressure.
Conformance shall be assessed by testing with the method in Clause B.14.
3.6.3 Tripping pressure
Where the tripping pressure of a device is independent of the inlet pressure, the maximum tripping pressure shall not vary from the set pressure by ± 20 % when the inlet pressure is varied across the full range specified by the manufacturer up to and including the rated working pressure at any one setting.
Conformance shall be assessed by testing with the method in CIausel3J.4.
3.6.4 Tripping pressure accuracy
The tripping pressure shall not vary from the set pressure by ± 10 % when the temperature is at 0 °C and 60 °C, or as specified by the manufacturer if a greater temperature range is specified.
3.7 Closing time
3.7.1 Time to close after tripping — Manufacturers tripping pressure range
The device shall close in a time not greater than 2 s when tripped over the tripping pressure range specified by the manufacturer.
Conformance shall be assessed by testing with the method in Clause B.13.
3.7.2 TIme to close after tripping — Device independent of inlet pressure
Where the tripping pressure of a device is independent of the inlet pressure, it shall close in a time not greater than 2 s when tripped with inlet pressures from the minimum tripping pressure specified by the manufacturer to the rated working pressure.
Conformance shall be assessed by testing with the method in Clause B.13.
3.8 Durability
3.8.1 Over-pressure shut-off device — Endurance
An over-pressure shut-off device set to the maximum of its range shall meet the requirements of Clause 3.6.2 before and after an endurance test of 100 closure cycles at ambient temperature and 50 closure cycles at the minimum operating temperature specified by the manufacturer, which shall be not greater than 0 °C. The mean values determined before and after the endurance test shall not vary by more than ± 5%.
Conformance shall be assessed by testing with the method in Clause 8.15.
3.8.2 tinder-pressure shut-off device — Endurance
An under-pressure shut-off device set to the minimum of Its range shall meet the requirements of Clause 3.6.2 before and after an endurance test of 100 closure cycles at ambient temperature and 50 closure cycles at the minimum operating temperature specified by the manufacturer, which shall be not greater than 0 °C. The mean values determined before and after the endurance test shall not vary by more than ± 5 %.
Conformance shall be assessed by testing with the method in i1sE.1.
3.8.3 Gas leakage after performance testing
An over-pressure or under-pressure shut-off device shall meet the requirements of Clauses 3.2.1 and 322 after all other performance requirements in Scctiwi have been completed.
Conformance shall be assessed by testing with the method in Clause 8.15.
3.8.4 Weight of diaphragm material
The diaphragm material shall not show a change in weight exceeding — ± 20 % after immersion in n-pentane for 72 h; and
± 10 % after a further 24 h drying in air.AS 4632-2020 pdf download.
Over-pressure and under-pressure shut-off devices
