It is never a good idea to allow corrosive chemicals or hydrocarbons to leak from their containment vessel. This is particularly true in a commercial building or institutional facility where customers, guests, patients, and other individuals not familiar with these materials have the potential to come into contact with them. This is a safety issue first and a liability issue second.
However, elevator pits represent an additional and different type of safety threat. Should hydraulic oil leak into an elevator pit from an elevator hydraulic system and then the building become involved in a fire, the hydraulic oil could have an impact on the speed with which the fire can be controlled.
If equipment located in an elevator pit develops a hydraulic oil leak, a layer of hydraulic oil will build on the pit floor. When firemen then put water on a fire, the water finds its way to the bottom of the pit and the oil floats on top. When the pit is full, additional water making its way into the pit pushes the oil out the top. When the oil leaves the confinement of the pit, it begins to spread. At this point, adding more water only spreads a high-grade fuel into the fire. Water is no longer a suitable tool for fighting the fire.