Sewage back-up alarm

An apparatus for sensing the pressure of sewage backup conditions in a sewer system, said apparatus comprising in combination:

• (a) connecting means having an interior region and first and second openings into said interior region, said connecting means being connected in sealed relationship with a sewer pipe so that there is a continuous channel from the interior of said sewer pipe through said first opening into said interior region, whereby backed up sewage can flow from said sewer pipe into said interior region;
• (b) pop-off covering means engaging said connecting means and responsive to pressure in said interior region caused by backing up of sewage in said sewage pipe for covering said second opening when the pressure in said interior chamber is low and popping off of said connecting means when said sewage backs up in said sewage pipe;
• (c) sealing means for sealable engagement with both said pop-off covering means and a portion of said connecting means surrounding said second opening to effect an air-tight, waterproof connection of said pop-off covering means with said connecting means until the pressure due to sewage backup in said interior region reaches a predetermined level;
• (d) first and second electrical conducting means extending into said interior region from outside of said connecting means for making electrical contact with sewage backed up into said interior region, whereby a reduced electrical resistance between said first and second electrical conducting means is produced as a result of said electrical contact with said backed up sewage;
• and
• (e) electrical alarm means coupled to said first and second electrical conducting means for producing an alarm signal indicating the presence of said backed up sewage in said interior region.