Formula

P₂ = ((P₁ + 14.696) × ((T₂ + 459.67) ÷ (T₁ + 459.67))) − 14.696

Gauge pressure is converted to absolute pressure before calculation. Temperature is converted to absolute temperature before comparison.

Assumptions

• Pressure inputs are psig.
• Temperature inputs are °F.
• The tested volume is sealed and does not change.
• Nitrogen behavior is estimated using the ideal-gas relationship.

Warnings

• This estimates temperature-caused pressure change only.
• This does not prove whether a system is leaking.
• Verify gauge accuracy, hose stretch, stabilization time, and test temperature before calling the result pressure loss.
• Follow equipment rating, approved test procedure, and jobsite safety requirements.

Advanced Setting

Use the default unless you intentionally need a different local atmospheric pressure value.

Formula

Micron rise = current micron reading − starting micron reading 1-hour rate = micron rise ÷ elapsed hours Projected 24-hour rise = hourly rise rate × 24 Reference comparison = hourly rise rate compared to selected microns/hr limit

Higher micron readings mean deeper vacuum was lost. Lower current readings mean the vacuum improved during the selected window.

Assumptions

• Micron readings come from the same gauge or comparable gauge setup.
• The system was isolated before the standing vacuum check.
• Elapsed time defaults to 1 hour.
• Quick options are 10 minutes, 30 minutes, and 1 hour.
• Use the preset test duration that best matches the standing vacuum check window.
• Rise rate is displayed in microns per hour and projected across 24 hours.
• Default reference is 1,000 microns in 24 hours, approximately 42 microns per hour.
• Additional reference is 1,300 microns in 24 hours, approximately 54 microns per hour.
• The 1,300 micron reference assumes pulling down to roughly 500 microns before isolation when that procedure applies.
• References are comparison aids, not universal pass/fail rules. Use the manufacturer procedure, customer requirement, site standard, or approved job procedure when one is specified.

Warnings

• This calculator does not prove a system is dry.
• This calculator does not prove a system is leak-free.
• The 24-hour projection assumes the entered test-window rate continues, which may not happen in the field.
• Micron rise can be affected by trapped moisture, oil, gauge placement, hoses, core tools, valve position, temperature, and isolation method.
• Follow the equipment procedure and jobsite requirements before charging or returning equipment to service.