Some Information about Plumbing and Plumbing tools
A check valve is a mechanical device, a valve, that normally allows fluid to flow through it in only one direction. A double check valve is often used as a backflow prevention device to keep potentially contaminated water from siphoning back into municipal water supply lines. A clapper valve is a type of check valve used in or with firefighting, and has a hinged gate (often with a spring urging it shut) that will only remain open in the outflowing direction.
Some Plumbing DOs and DON'Ts
DO - If you can't put heat in an area where water pipes are, use
an electric heat tape.
DO - If your kitchen sink is located on an outside wall, leave
cupboard doors open in severe cold weather.
DO - Shut off all outside faucets in cold weather if they are
not of the frost proof type.
DO - If you are closing up a home in the wintertime and there
will be no heat in the home, shut off the water supply at the
street or in the basement.