Why using a diesel fire pump in an oil and gas industry?

Using diesel fire pump in the oil and the gas industry it is economical compared to the electric driven and it is still working if case the electrical shut off due to the uncontrol fire.

Electrical pump may trip due to power failure, that caused by the fire which has to be extingueshed . but the deised fire pump will continue to run to fighting the fire  regardless of electrical power failure 

Because, unlike other types of pumps which uses gas or gasoline fuels, diesel pumps do not create or need a spark for ignition.

Because it's recommanded by the NFPA20 , we use both electrical and diesel motor driven pumps for firefighting system