Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1978-04-25
1980-07-08
Caldwell, Sr., John W.
Communications: electrical
Condition responsive indicating system
Specific condition
116 70, 116218, 137557, 200 83D, 200 83J, 340626, G08B 1704, H01H 3740
Patent
active
042120047
ABSTRACT:
Pressure drop detectors are provided which are suitable for use in pressurized fluid fire alarm systems. The pressure drop detectors have pressurized fluid circuits provided as channels in the surface of a block of material, including one channel connected to a source of fluid pressure. The channels are associated with valve regions by means of which, with a first diaphragm pressed thereagainst, a required one or more of the channels can be closed off.
The pressure drop detectors have a normally pressurized region of the first diaphragm which by means of a first piston normally supports a mechanical linkage of the detector. If the pressure drops however on release of pressure in the circuit connected to the detector, the collapsing of the first diaphragm allows the mechanical linkage to be released thus actuating a fire alarm. A second diaphragm and an associated second piston are acted on by the main pressure supply and the second piston applies a bias to the mechanical linkage dependent on the pressure of the main supply. Accordingly, the reduced pressure in the circuit required for the release of the mechanical linkage is now a nominated difference in, or a percentage of, the pressures existing in the circuit and the main supply rather than any specific pressure.
REFERENCES:
patent: 1584870 (1926-05-01), Lagergren
patent: 2334826 (1943-11-01), Lowe
patent: 3109409 (1963-11-01), Demzy
patent: 3119368 (1964-01-01), Barnard
patent: 3448442 (1969-06-01), Hube
patent: 3772671 (1973-11-01), Owen
Benefis Systems Limited
Caldwell Sr. John W.
Nowicki Joseph E.
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