Open valves by hand, not with a wrench or other tool. If they don't open, notify the supplier. Don't tamper with safety devices. Open, then close, valves quickly. Then open them slowly, standing to the side, rather than in front of the outlet.
Caution is the watchword with compressed gases .
You have to be extremely careful with them, and you have to be especially careful that they don't come in contact with anything that can create fire or explosion. Read the MSDS to check on all hazards and possible reactions and take the fire and explosion risks very seriously. Don't refill a cylinder. Be sure a person trained and equipped for fire fighting is with you. Don't try to fix a cylinder leak or valve or any other problem.