Upset (Process)

An undesirable process event that causes process variables, such as flow, temperature, level, etc., to vary outside their design range. Two simple examples where an upset can lead to rotating machinery problems: a sudden loss of liquid level in a process vessel can lead to pump cavitation; an upset that results in a higher than normal product temperature can lead to a mechanical seal failure due to flashing across the seal faces. It is important to train process operators to deal with upsets so they can return process units back to normal conditions as quickly as possible to avoid permanent equipment damage.