double block and bleed system

double block and bleed system

[′dəb·əl ¦bläk ən ′blēd ‚sis·təm]
(engineering)
A valve system configuration in which a full-flow vent valve is installed in a pipeline between two shutoff valves to provide a means of releasing excess pressure between them.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.