alarm value setting standard for hydrogen alarm:

the primary alarm value should be less than or equal to 25% LEL, I .e. 25% of the lower explosive limit (LEL) of hydrogen; The secondary alarm value should be less than or equal to 50% LEL, that is, 50% of the lower explosive limit (LEL) of hydrogen. These settings are based on the provisions of GBT 50493-2019 Petrochemical Combustible and Toxic Gas Detection and Alarm Design Standard (official version).

for detectors with a hydrogen alarm measuring range between 3% LEL and 100 LEL, the upper limit of the range should be 100 LEL and the lower limit alarm setting value Should be in the range of 5% LEL ~ 25% LEL, if there is a high limit alarm setting value, it should be 50% LEL. If the low limit alarm setting value is adjustable, it shall be adjustable within the range of 5% LEL ~ 25% LEL.

when the concentration of H2 combustible gas in the environment reaches or exceeds the prefabricated alarm, the controller immediately sends out an audible and visual alarm hydrogen alarm to prompt the timely adoption of safety measures and linkage of exhaust fans or other equipment to avoid blasting.