STOP BASEMENT FLOODING NOW

Failure Modes and Effects Analysis - A technique for systematically identifying potential failures in a system and the consequences of those failures.  Understanding the different ways that individual components can fail is important in determining the overall probability of total system failure.

Fault Tree - A fault tree model consists of a collection of events that represent failures to be analyzed.  They are connected together by a logic structure of gates that represent the combinations of failures that result in the occurrence of other failures.  Each fault tree will have a top event, intermediate events, and basic events.  By definition, a fault tree can have but a single top event.  Intermediate events are events that can be caused by either basic events, other intermediate events, or a combination of the two, and which are inputs to either other intermediate events or to the top event.  Basic events are events that represent the basic failures to be analyzed, and which are not evaluated further.

The events in the fault tree are connected by several types of gates.  Gates utilized in the fault tree model include AND gates and OR gates.  An AND gate is used to model a failure which will occur only if all of the input failures occur simultaneously.  An OR gate is used to model a failure which will occur if any one of the input failures occurs.

Inverter - A device used to convert direct current from 12 Volt batteries into 120 Volt alternating current like you would get from any household outlet.

Reliability - The probability that a system or component successfully performs its intended function for a specified period of time.

Risk - The product of the likelihood of an event occurring and the consequence or loss from the event.  For someone with an empty basement, their basement could flood frequently, but because there is no consequence, there is no risk.  For someone else, the likelihood of a flood may be low based on past experience.  However, if there is a substantial investment in finishing a basement, the consequence of a flood would be very high, such that the risk is high.

Single Failure Points - Single component failures that can disable an entire system.  For example, in a two pump system with a common discharge line, blockage of the discharge line is a single failure point since it would disable both pumps.

Last modified: 05/22/08