Improvements relating to tanks for liquid foam-stabilising materials and to liquid-level indicating devices for use therein

801,017. Indicating liquid levels. PYRENE CO., Ltd. Jan. 24, 1957 [Jan. 24, 1956], No. 2333/56. Class 123(1) The level of liquid foam - stabilizing material in a closed tank forming part of a foam-making fire fighting appliance in which water under pressure admitted to the top of the tank displaces the heavier liquid material therefrom and feeds it to the foam generators, is indicated by a float which sinks in water but floats on the liquid material and is arranged to operate or forms a visible indicator. The float may carry a stick which extends into a slight glass at either the top or the bottom of the tank. In another form, as shown in the Figure, a float 9 is mounted on an arm 10 attached to a holder 8 having a stem 7 secured in a block 6 which pivots on pins 5 carried by brackets 4 mounted on a circular body 2 of non- magnetic material such as brass secured in a hole cut in the wall 3 of the tank. Projecting from the block 6 is a fork 11 which co-operates with a pin 12 projecting from a block 13 which is itself attached to a rotatable magnet 14 carried on a pin 15. The indicator is a pointer 1 carried on a pin 17 and turned by the magnet 14. The float may be hollow but preferably is solid and made from polystyrene or polymethyl methacrylate which are materials of appropriate specific gravity.