An automatic liquid level indicator and alarm system (10) that automatically emits an alarm when liquid in a vessel reaches a preselected low or high level. The system (10) is particularly adaptable for use on petroleum storage tanks (50) of the type found on petroleum tank farms. The system (1) comprises...http://www.google.ca/patents/US4459584?utm_source=gb-gplus-sharePatent US4459584 - Automatic liquid level indicator and alarm system
