The Double Block and Bleed Valve or a DBBV can execute the responsibilities of 3 separate Valves. It consists 2 separate solitude and 1 drain Valve which apart from being greatly space saving. It can also save on weight and time due to assembly and repair practices requiring much less work and the operator being able to locate and operate all 3 Valves in one location. Double block and bleed Valves work on the concept that solitude can be obtained from both the upstream and downstream process flow or pressures. This is obtained by two ball, gate, globe, needle and many more. Valves located back to back with a third "solitable" Valve in the center cavity. Once solitude has been obtained in one or more of the main procedure solitude Valves the cavity that is created between these isolation can be cleared. This is useful for flow directing, testing or injection situations and for servicing or strength check situations where seat leakage can be examined through the third "bleed" Valve
Dual solitude is an important prerequisite when maintenance is taking place down stream of the first solitude valve. Cavity ventilation is provided by either a ball or globe OS&Y vent valve so that stuck strain between the two solitude valves is safely vented. These item has also developed to consist of the functionality of chemical injection (using an acceptable quill) and test points. Check valves are frequently included in DBB valves. The key functionality of a these item is for isolation and the secondary function is for involvement(diverting / sampling / injection etc). It is also fantastic for diminished risk of vibration damage. Some supplemental features include indicator, check valves and injection quills. Double block and bleed valves are typically made from 316 stainless steel with steady flow for very insignificant pressure drop.