How long must you wait to use acetylene if it was on its side?

If acetylene cylinders have been on their side, you should wait at least 30 minutes before using them. This allows any liquid acetylene that may have entered the valve to evaporate and return to a gaseous state. Always check for proper cylinder orientation and ensure the cylinder is returned to an upright position before use. Safety is paramount when handling acetylene due to its flammability and potential hazards.