Anti-backflow valve for therapy tubs and the like

An anti-backflow valve adapted to be installed in a pipe to permit gas flow in one direction and to preclude flow of a liquid in the pipe in the opposite direction, said valve comprising:

• (a) a housing having a gas inlet, a gas outlet, and a chamber communicating with said inlet and outlet;
• (b) means for preventing fluid flow outwardly through said inlet;
• (c) means for venting said chamber in response to a pressure therein greater than a predetermined relief pressure;
• and
• (d) means for draining said chamber in response to the presence of liquid therein above a predetermined level, said means for venting and said means for draining comprising, in common, a discharge port in said chamber and a port closure member for unblocking said discharge port in response to either gas pressure or liquid above selected levels.

An anti-backflow valve adapted to be installed in an air blower discharge line of a therapy tub aeration system to protect the blower from backflowing tub water in the discharge line, said valve comprising:

• (a) a housing having an air inlet, an air outlet, and a chamber communicating with said air inlet and outlet;
• (b) means defining an auxiliary outlet passage from said chamber remote from said air inlet and outlet;
• (c) check valve means in said chamber for blocking fluid flow outwardly through said air inlet;
• and
• (d) combined pressure relief and float valve means in said chamber for normally blocking said auxiliary outlet passage and for opening said auxiliary outlet passage in response to a pressure in said chamber above a predetermined relief pressure or the presence of water in said chamber above a predetermined level.

A combined air pressure relief and water discharge valve for protecting an air blower of a pool, spa, therapy tub or the like against backflowing water and air pressure surges, said valve comprising:

• (a) a chamber adapted to communicate with the discharge side of an air blower to be protected;
• (b) a discharge port in said chamber;
• (c) a discharge port closure member movably mounted in said chamber for motion between port blocking and unblocking positions, said closure member including means responsive to air pressure in said chamber for applying a differential air pressure to said closure member to shift said closure member to said unblocking position to relieve air pressure within said chamber;
• and
• (d) means for discharging water from said chamber, said means for discharging water from said chamber comprising said discharge port, said closure member being buoyant and being mounted for movement up and down between said positions in response to the level of water in said chamber.

An anti-backflow valve adapted to be installed in an air blower discharge line of an aeration system to protect the blower from backflowing water inthe discharge line, said valve comprising:

• (a) a housing having an air inlet, an air outlet and a chamber communicating with said inlet and outlet;
• (b) means in said chamber defining a combined drain and relief port;
• and
• (c) normally closed valve means in said chamber responsive to either air pressure within said chamber above a predetermined value or a water level within said chamber above a predetermined value for opening said combined relief and drain port.