Fire extinguishers – Sprinkler heads – Shut off valve
Patent
1992-03-16
1994-04-19
Mitchell, David M.
Fire extinguishers
Sprinkler heads
Shut off valve
137221, 251 44, A62C 3721
Patent
active
053037782
ABSTRACT:
In an automatic turn-off sprinkler, water enters an inlet and passes through a hollow interior region to the outlet. A reciprocating spool in the hollow region normally blocks the outlet enabling incoming water to fill a chamber above the spool. The gap between the ID of the bore and the OD of the spool permits sliding movement of the spool while providing a watertight seal preventing liquid entering the small opening communication with a chamber above the top of the spool from passing to the outlet opening. A heat sensor detects an emergency condition, unsealing a normally sealed opening allowing liquid pressing upon the spool to escape through the unsealed opening dropping the pressure on the top of the spool, whereby water pressure upon the bottom of the spool lifts the spool above the outlet. When the heat sensor seals the control opening, liquid pressure upon the top surface builds. Although pressure on the bottom and top surfaces is substantially equal, gravity urges the spool to the closed position which is maintained during normal conditions. The watertight seal is retained by controlling gap size, eliminating the need for O-ring seals which create undesirable frictional forces. The spool may be spherical or cylindrical. A light closing spring may be provided to normally urge the spool to the closed position. A plurality of on-off sprinkler devices may be controlled by a common heat sensor, if desired.
REFERENCES:
patent: 3757866 (1973-09-01), Mears et al.
patent: 3791450 (1974-02-01), Poitras
patent: 3802510 (1974-04-01), Johnson
patent: 3848676 (1974-11-01), Doherty, Jr.
patent: 4359098 (1982-11-01), Johnson
patent: 4553602 (1985-11-01), Pieczykolan
Mitchell David M.
Pike Andrew C.
Weinstein Louis
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