What type of skid is required for diesel fuel treatment to increase the flash point?

For on-site blending of diesel with additives (winter or Arctic blends) the typical skid you want is a skid-mounted hydrodynamic cavitation mixing unit (USB family). These skid-mounted units (also available in containerized or trailer-mounted formats) perform in-line injection and high-shear hydrodynamic impact to produce stable, high-dispersion mixtures of two to seven constituents, with capacities commonly in the 18–100 m3/h range depending on model and duty.

If your primary objective is purification—removing free and emulsified water, particulates and polishing color/odor—you’d look at fuel dehydration/polishing skids that incorporate separation, filtration and heating stages (typical CMM-style polishing units). Note that these mixing and polishing skids are not described as flash-point–raising systems; changing flash point usually requires different blending or refinery-type treatments and should be validated by lab testing. If you tell me your target flow rate and whether you need blending, dehydration or both, I can recommend the appropriate skid configuration.