Product

Typical VDU side-cut structure (top to bottom)

1. Vacuum Diesel (VD) / Vacuum Distillate / Wash oil — the lightest side cut from the Vacuum Distillation Unit (VDU), roughly the TBP range ~350–430/450 °C (atmospheric equivalent). It’s the overlap/tail of the diesel boiling range that couldn’t be recovered in the atmospheric column.

2. Light VGO (LVGO) — ~380/400–470 °C

3. Medium/Intermediate VGO (MVGO / IVGO) — ~470–510 °C (only drawn in units with three VGO grades)

4. Heavy VGO (HVGO) — ~500–560/580 °C (endpoint set by metal/asphaltene contamination and downstream unit constraints)

Correspondence between VD and LVGO

• Where Vacuum Diesel is drawn, it essentially replaces or overlaps the LVGO. Many refineries use the terms loosely: a “Vacuum Gas Oil” cut whose endpoint is kept low (≤ ~450 °C) is often marketed/used as vacuum diesel (e.g., for ULSD blending, heating oil, or as low-sulfur marine fuel component). So VD ≈ LVGO (or its lighter portion).

• Where LVGO/MVGO/HVGO are drawn, there is usually no separate “vacuum diesel” cut — the LVGO itself serves that role (FCC or hydrocracker feed, or diesel-pool blending after hydrotreating).

• The key practical distinction is fate: “Vacuum Diesel” implies the stream is destined for the distillate (diesel) pool after desulfurization, whereas “VGO” (L/M/H) implies conversion-unit feed (FCC, hydrocracker). Same boiling material, different labels.

Caveat

Cut point naming is site-specific — some VDUs draw “light vacuum gasoil” and “vacuum diesel” as separate products with overlapping TBP ranges. In this case the unit’s TBP/ASTM D1160 cut-point definitions should be checked rather than relying on the stream name.

Density Values

Typical densities for vacuum gasoil cuts (at 15 °C, straight-run material from a VDU):

Key points

• Density climbs steadily with boiling range because heavier cuts contain progressively more aromatics and naphthenics (higher density per carbon number) and fewer paraffins.

• The crude source matters a lot: VGO from a paraffinic crude (e.g., WTI, some West African) can sit at the low end (~0.88–0.90 for HVGO), while VGO from heavy, aromatic, high-sulfur crudes (e.g., Maya, Urals, Middle East heavy) can push HVGO to 0.94–0.96 g/cm³.

• A full-range VGO (LVGO+MVGO+HVGO composite) typically assays around 0.90–0.93 g/cm³ (~20–25 °API).

• Don’t confuse these with cracked gasoils (LCGO, HCGO from FCC/cokers), which are much more aromatic and denser — often 0.95–1.05 g/cm³.