Les classes de pression de vannes sont généralement exprimées en bar ou en PSI (pounds per square inch), avec des valeurs standardisées comme 10, 16, 25, 40, 63, 100, 160, 250, 400, 630, 1000, 1600, 2500, 4000, 6300, 10000, 16000, 25000, 40000, 63000, 100000, 160000, 250000, 400000, 630000, 1000000, 1600000, 2500000, 4000000, 6300000, 10000000, 16000000, 25000000, 40000000, 63000000, 100000000, 160000000, 250000000, 400000000, 630000000, 1000000000, 1600000000, 2500000000, 4000000000, 6300000000, 10000000000, 16000000000, 25000000000, 40000000000, 63000000000, 100000000000, 160000000000, 250000000000, 400000000000, 630000000000, 1000000000000, 1600000000000, 2500000000000, 4000000000000, 6300000000000, 10000000000000, 16000000000000, 25000000000000, 40000000000000, 63000000000000, 100000000000000, 160000000000000, 250000000000000, 400000000000000, 630000000000000, 1000000000000000, 1600000000000000, 2500000000000000, 4000000000000000, 6300000000000000, 10000000000000000, 16000000000000000, 25000000000000000, 40000000000000000, 63000000000000000, 100000000000000000, 160000000000000000, 250000000000000000, 400000000000000000, 630000000000000000, 1000000000000000000, 1600000000000000000, 2500000000000000000, 4000000000000000000, 6300000000000000000, 10000000000000000000, 16000000000000000000, 25000000000000000000, 40000000000000000000, 63000000000000000000, 100000000000000000000, 160000000000000000000, 250000000000000000000, 400000000000000000000, 630000000000000000000, 1000000000000000000000, 1600000000000000000000, 2500000000000000000000, 4000000000000000000000, 6300000000000000000000, 10000000000000000000000, 16000000000000000000000, 25000000000000000000000, 40000000000000000000000, 63000000000000000000000, 100000000000000000000000, 160000000000000000000000, 250000000000000000000000, 400000000000000000000000, 630000000000000000000000, 1000000000000000000000000, 1600000000000000000000000, 2500000000000000000000000, 4000000000000000000000000, 6300000000000000000000000, 10000000000000000000000000, 16000000000000000000000000, 25000000000000000000000000, 40000000000000000000000000, 63000000000000000000000000, 100000000000000000000000000, 160000000000000000000000000, 250000000000000000000000000, 400000000000000000000000000, 630000000000000000000000000, 1000000000000000000000000000, 1600000000000000000000000000, 2500000000000000000000000000, 4000000000000000000000000000, 6300000000000000000000000000, 10000000000000000000000000000, 16000000000000000000000000000, 25000000000000000000000000000, 40000000000000000000000000000, 63000000000000000000000000000, 100000000000000000000000000000, 160000000000000000000000000000, 250000000000000000000000000000, 400000000000000000000000000000, 630000000000000000000000000000, 1000000000000000000000000000000, 1600000000000000000000000000000, 2500000000000000000000000000000, 4000000000000000000000000000000, 6300000000000000000000000000000, 10000000000000000000000000000000, 16000000000000000000000000000000, 25000000000000000000000000000000, 40000000000000000000000000000000, 63000000000000000000000000000000, 100000000000000000000000000000000, 160000000000000000000000000000000, 250000000000000000000000000000000, 400000000000000000000000000000000, 630000000000000000000000000000000, 1000000000000000000000000000000000, 1600000000000000000000000000000000, 2500000000000000000000000000000000, 4000000000000000000000000000000000, 6300000000000000000000000000000000, 10000000000000000000000000000000000, 16000000000000000000000000000000000, 25000000000000000000000000000000000, 40000000000000000000000000000000000, 63000000000000000000000000000000000, 100000000000000000000000000000000000, 160000000000000000000000000000000000, 250000000000000000000000000000000000, 400000000000000000000000000000000000, 630000000000000000000000000000000000, 1000000000000000000000000000000000000, 1600000000000000000000000000000000000, 2500000000000000000000000000000000000, 4000000000000000000000000000000000000, 6300000000000000000000000000000000000, 10000000000000000000000000000000000000, 16000000000000000000000000000000000000, 25