A percentage needs a reference basis as well as a number.
Retain the percentage definition
Schmalz identifies absolute pressure separately from relative percentage indications in its vacuum terminology. Preserve the supplier's actual definition before converting. Primary reference: Schmalz vacuum measurement units.
For this teaching example only, define degree of vacuum as 100×(p_atmosphere−p_absolute)/p_atmosphere. That explicit definition expresses the reduction relative to the stated atmosphere. A purchasing comparison should not assume every unidentified percent field uses this convention or the same atmospheric reference.
Work a hypothetical reference comparison
Under an invented atmospheric basis of 100 kPa,60% by that definition corresponds to 40 kPa absolute. With a 95 kPa atmospheric basis, the same 60% corresponds to 38 kPa absolute. The two reference assumptions create different absolute pressures even though the percentage is unchanged.
Make cells for reported value, absolute/relative type, percentage definition, atmosphere and converted value. These are hypothetical numbers, not a site atmospheric measurement or an ejector performance claim. A vendor's stated reference basis must remain with its offered figure.
Keep conversion and performance separate
Ask what operating and measurement conditions accompany the offered vacuum level. A correctly interpreted pressure figure does not supply suction flow, grip retention or the complete capability curve. Retain those additional functions in separate evidence rows.
If offers use different units or percentage conventions, preserve their original statements beside the documented common comparison. This prevents a copied number from losing its meaning when imported into a utility schedule. The guide selects no vacuum setting and does not substitute a nominal atmosphere for an actual task without making that assumption explicit.
Customer Questions
Does 60% identify an absolute pressure without a basis?
No. Retain its definition and reference.
Does the same percentage always give the same absolute pressure?
No. The stated atmospheric basis matters.
Does pressure conversion prove suction flow?
No. Flow has separate evidence.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
Discuss Your Machine Requirement
Share your product, container, required output and the evidence needed for your technical review.
Request a Technical Review