Apparatus for detecting the level of liquid in a tank

Claim 1

In an apparatus for detecting the level of liquid preferably fuel oil in a fuel oil storing tank in a vessel to control the quantity of fuel oil in the tank for use with an alarm device, comprising a sensing pipe having a top portion closed and a lower portion inserted into said tank, a connecting pipe communicating with said sensing pipe at one end thereof, the other end thereof being open to the atmosphere, a fluid pressure response device defining a supply port, and exhaust port, a sensing port and an output port, and including a passage communicating said supply port with said exhaust port, said sensing port being connected to said connecting pipe at one end thereof, said output port being operatively connected to an alarm device, and gas supplying means communicating with said sensing pipe and communicating with said fluid pressure response device through said supply port, for continuously supplying gas to said sensing pipe and to said fluid pressure response device, the gas supplied to said sensing pipe being delivered through said sensing pipe to said exhaust port to be discharged therefrom, the gas supplied to said fluid pressure response device being delivered through said supply port and said passage to said exhaust port to be discharged therefrom, the improvement wherein: (a) said sensing pipe constitutes a sounding pipe disposed in the vessel and defines a sensing hole at a lower portion thereof, and (b) throttle means, disposed in said connecting pipe at a position between said one end of the sensing port and said other end of the connecting pipe opening to the atmosphere, for placing said fluid pressure response device in a desired operable state, whereby, when the level of fuel oil is raised higher than the level of said sensing hole, the pressure in said sounding pipe is increased and when the pressure in said sounding pipe reaches a value at which said fluid pressure response device is placed in a desired operable state, means for causing said fluid pressure response device to close said passage in response to said pressure to cause the gas to flow from said supply port to said output port to operate the alarm device, said throttle means for adjusting said pressure thereby to detect the level of fuel oil in said tank above said sensing hole.