High-pressure reactions are those experiments that are carried out at pressures above one atmosphere. This includes most hydrogenation reactions since explosive oxygen-hydrogen mixtures can be formed as a result of these reactions. 

Operational Practices 

• Pressure vessels should be labeled to indicate the maximum allowable working pressure and temperature. 
• Service lines shall not be not connected to any closed apparatus incapable of withstanding the maximum pressure of the service line (air, water, etc.). 
• All pressure systems shall be  protected with  appropriate pressure-relief devices. 
• The pressure-relief device shall be  installed so that the discharge is directed away from the area where a person could be affected (preferably toward the back of a hood)  
• Pressure-relief devices shall be inspected periodically by lab staff. Orifices on both sides of the pressure-relief device should be checked for obstruction. 
• Pressure gauges with pressure ranges about twice the working pressure of the system shall be used.
• Containers, fittings, and other equipment to be used when working with pressure vessels shall be chosen to able to withstand the stresses imposed by the given pressures and temperatures. 
• Pressure vessels containing liquids shall not be filled above capacity (no more than half full is preferred). 
• The pressure levels of high-pressure devices shall be monitored periodically as heating proceeds.