“The 1:1 Rule for Quench Tanks: A Suboptimal and Misapplied Design Criterion”

There is an oft quoted rule of thumb in heat treating: quench tanks should be sized with one gallon of oil per one pound of steel.  The intent of this “1:1 rule” is to prevent quench tank fires.  As with most rules of thumb, the 1:1 rule was formulated for ease of memorization and to give a significant margin of safety.  Over the years, testing, data and experience have shown the rule to be overly conservative in certain cases, especially when applied to batch integral quench furnaces. Moreover, the rule has been mistakenly applied as a metallurgical quality specification, which is not its purpose.

This paper will discuss critical safety and process parameters of the quenching process and equipment design that the simplistic 1:1 rule fails to consider.