Abstract: A liquid-projecting monitor of the spherical head type has its head sealing against a housing which defines together with the head a chamber from which liquid is lead into a passage in the head and then to a nozzle coupled to the head. The head is borne by a horizontal axle for pivotal movement relative to the housing so as to adjust the angular elevation or depression of the nozzle. A center body extends transversely across the interior of the head to enclose the axle and is so shaped, together with the internal surface of the head, that the cross-sectional area of the passage within the head available for liquid flow is maintained at least approximately constant throughout its length, so as to minimize the pressure drop in the liquid flow which passes through the head.

Abstract: A liquid-projecting monitor of the spherical head type has its head sealing against a housing which defines together with the head a chamber from which liquid is lead into a passage in the head and then to a nozzle coupled to the head. The head is borne by a horizontal axle for pivotal movement relative to the housing so as to adjust the angular elevation or depression of the nozzle. A center body extends transversely across the interior of the head to enclose the axle and is so shaped, together with the internal surface of the head, that the cross-sectional area of the passage within the head available for liquid flow is maintained at least approximately constant throughout its length, so as to minimize the pressure drop in the liquid flow which passes through the head.

Abstract: A heat detector having automatic gain control in relation to changes of time constant different from that of the changes to be detected, comprises an outer feedback loop including the light path between emitter (10) and detector (14), and an inner feedback loop (40,42,44) around the emitter drive circuit. The inner feedback loop contains an exponential element (42). The exponential response of the inner loop feedback circuit makes the open-loop gain and the time constant of the system invariable in spite of differences in the light path, for example in different installations.

Abstract: Concentrates suitable for making fire-fighting liquids upon sixteen-fold dilution are described comprising particular perfluoro ampholytic surfactants, solvents and fluorine-free surfactants. The ampholytic surfactants are of the general formula ##STR1## wherein n represents an integer of from 1 to 20, a represents an integer of from 2 to 10, q represents an integer of from 0 to 10, p represents an integer from 0 to 10 and each of R.sub.1, R.sub.2 and R.sub.3, which may be the same or different, are hydrogen, C.sub.1-6 alkyl orC.sub.n F.sub.2n+1 --(CH.sub.2).sub.a --SO.sub.2the solvent is a glycol or glycol ether preferably butyldigol or butyl cellosolve. When the preferred fluorine-free surfactants are used the solutions obtainable on dilution will form a film on n-hexane. The concentrates contain less than 2% of the perfluoro surfactant.