Velan Wafer Check Valve

check valve
A valve that closes to prevent backward flow of liquid
A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid (liquid or gas) to flow through it in only one direction.
Limits the flow of gas to one direction only. Use a check valve between the bubbler and generator to prevent unwanted pressure build up in the generator, and a safety against a low level bubbler. A check valve, such as used on torches, is recommended.
A mechanical device in a pipe that permits the flow of water or air in one direction only.

velan
Murugan (???????, ????????), also called Subrahmanya (???????????,???????????????? ??????), is a popular Hindu deity among Tamil Hindus, worshipped primarily in areas with Tamil influence, especially South India, Singapore, Sri Lanka, Malaysia and Mauritius.
The verb velar isn't particularly common. In this context it means "to keep watch" or "to take care."

wafer
a small adhesive disk of paste; used to seal letters
Fasten or seal (a letter, document, etc.) with a wafer
a small thin crisp cake or cookie
thin disk of unleavened bread used in a religious service (especially in the celebration of the Eucharist)