Diaphragm Expansion Tank Sizing

Overview

Engineering reference data for Diaphragm Expansion Tank Sizing in standard organizations.

Key Formulas

ISO Standard

$ISO \; 9001:2015$

Quality management systems.

ASTM Standard

$ASTM \; E8$

Standard test methods for tension testing.

ANSI Standard

$ANSI/ASME \; B16.5$

Pipe flanges and flanged fittings.

Variables

Reference Operating Conditions

The standard diaphragm expansion tank sizing chart uses the following baseline conditions:

Correction Factor Method

When your system operates at different initial and maximum pressures than the reference conditions above, apply a correction factor to the estimated tank volume:

$V_{actual} = V_{reference} \times C_f$

Where:

• $V_{actual}$ = required tank volume at actual operating conditions
• $V_{reference}$ = tank volume from the standard sizing chart
• $C_f$ = correction factor based on actual pressure conditions

The correction factor $C_f$ accounts for the relationship between the system's pressure differential and the reference pressure differential. As the ratio of maximum to initial pressure increases beyond the reference values, a larger correction factor is required.

Sizing Notes

• Safety Factor (~2): Applied to account for uncertainties in system volume estimates and potential future system modifications
• Acceptance Factor (~0.5): Represents the fraction of tank volume available for fluid expansion (typically 50% for standard diaphragm tanks)

References

• Original Source