Bleed Off is to extract or let out partially or all of a contained substance that is to relieve pressure from the equipment or system.
Reference Definition by Schlumberger Oilfield Glossary: Bleed Off means to equalize or relieve pressure from a vessel or system. At the conclusion of high-pressure tests or treatments, the pressure within the treatment lines and associated systems must be bled off safely to enable subsequent phases of the operation to continue. The bleedoff process must be conducted with a high degree of control to avoid the effect of sudden depressurization, which may create shock forces and fluid-disposal hazards.
