Start with the sample, boiling curve and product contract
Pressure is an operating variable, not a quality badge. A defensible choice connects a representative sample to a laboratory curve, an agreed cut plan and measurable acceptance criteria.
| Required input | Question to answer | Decision effect |
|---|---|---|
| Sampling plan and batch history | Does the sample represent seasonal, supplier and tank-bottom variability? | If not, hold equipment selection and build a composite sampling plan. |
| Water, solids, metals and additive screen | What must be removed or isolated before heat and vacuum are applied? | Defines dehydration, filtration, fouling control and bottoms handling. |
| Atmospheric and reduced-pressure boiling data | Where are useful cuts recovered, and where does cracking or degradation begin? | Supports atmospheric-only or a staged atmospheric-plus-vacuum train. |
| Target product and residue specification | Which fraction properties, test methods and end-use rules form acceptance? | Defines cut points, polishing scope and whether distillation is only one step in regeneration. |
Three shortcuts that invalidate the comparison
“Atmospheric is always simpler”
It may still require dehydration, solids removal, controlled condensation and a defined residue route.
“Vacuum means higher quality”
Lower pressure can reduce boiling temperature, but product quality still depends on feed contaminants, separation, polishing and acceptance tests.
“Combined is automatically better”
Extra stages add interfaces and controls. They are justified only when the tested boiling range and product value support them.
Minimum evidence for a supplier review
Send facts that can be checked, not a requested pressure mode alone.
- Representative sample method and batch range
- Water, solids, viscosity/density and relevant contaminant results
- Distillation or simulated-distillation curve with test method
- Target fractions, end use and acceptance tests
- Residue, wastewater, condensate and non-condensable-gas route
- Required throughput, operating hours and site utilities