The invention discloses an automatic
internal pressure alarm
system of a sealing film used in vacuum combined surcharge preloading. A pressure gauge of a vacuum preloading device is an
electric contact pressure gauge; a normally-
open contact of the
electric contact pressure gauge is connected in parallel with one auxiliary normally-
open contact of an intermediate
relay and is then connected in series with a normally-closed contact of a
reset button to a coil power supply loop of the intermediate
relay; and another auxiliary normally-
open contact of the intermediate
relay is connected in series to a power supply loop of an audible and visual alarm. According to the automatic
internal pressure alarm
system, a structure that the
electric contact pressure gauge and the audible and visual alarm work cooperatively is adopted, when the
vacuum pressure is reduced to a set value, the audible and visual alarm is immediately started, and an operator on duty begin to check
gas leak points at the first time, so the project quality is benefited; and meanwhile, the time, the
machine fee and the
electric charge needed by re-arriving at a design pressure are decreased, and the construction cost is reduced. Furthermore, the automatic alarm
system has a simple structure, the mounting is convenient, the labor intensity is reduced to a great degree, the work efficiency is improved, the labor input is little, the cost is low, and the labor power, the
material resources and the financial resources are saved.