CT: The check valve was designed with a drive shaft that connects the internal valve disk to an external pneumatic cylinder. The valve failed when a dowel pin designed to fasten the drive shaft to the disk sheared and a key designed to transfer torque from the drive shaft to the disk fell out of its keyway, disconnecting the drive shaft from the disk. System pressure was high enough to eject the unrestrained drive shaft from the valve, carrying with it the external counterweight assembly, weighing over 200 lbs., a distance of 43 feet away.
S: EPA – http://www.epa.gov/ceppo/web/docs/chem/shell.pdf (last access: 9 December 2014)
N: 1. valve (n): Latin valva; akin to Latin volvere to roll. First known use: 14th century.
check (or nonreturn) valves, for example, are self-acting valves that permit flow in only one direction.
2. Check valve (Mech) a valve in the feed pipe of a boiler, or other conduit, to prevent the return of the feed water or other fluid.
3. Used in a plumbing system where protection from backflow is needed.
4. Systems directly connected to heat transport systems and which may be open during normal operation of the station shall also be provided with the same isolation as the normally closed system except that manual isolating valves inside the containment structure shall not be used. At least one of the two isolation valves shall be either an automatic isolation valve (for instance, a check valve) or a powered isolation valve operable from the control room.
S: 1. MW – http://www.merriam-webster.com/dictionary/valve (last access: 7 December 2014). 2. http://www.finedictionary.com/Check%20valve.html (last access: 7 December 2014). 3. GDT (last access: 7 December 2014). 4. TERMIUM PLUS (last access: 7 December 2014).
SYN: 1. nonreturn valve. 2. backwater valve.
S: 1. MW – http://www.merriam-webster.com/dictionary/valve (last access: 7 December 2014); GDT (last access: 7 December 2014). 2. PEEL – http://www.peelregion.ca/pw/water/sewage-trtmt/basement-flooding.htm (last access: 9 December 2014)