Sizing follows the equivalent-length / saturation-temperature-penalty method of
McQuay AG 31-011 “Refrigerant Piping Design Guide” (ASHRAE Refrigeration Handbook Ch. 2)
for R-410A, R-22, R-134a and R-407C (capacities in tons, corrected for SST, condensing
temperature, equivalent length and design ΔT with the 0.55-exponent relation), and the
Hussmann “Line Sizing Refrigeration Data Guide” (MBH tables) for R-404A/R-507A and
R-448A/R-449A. R-454B, R-454A, R-454C, R-1234yf and R-513A use the manufacturer capacity
tables from the Chemours “Opteon Refrigerant Piping Handbook” (pp. 22–28, Type L
copper, −60 to +40 °F SST), with condensing-temperature multipliers and riser
oil-return minimums borrowed (capacity-scaled) from the closest AG 31-011 refrigerant.
R-32 uses the R-410A tables per Daikin AG-TP-111 practice; R-290 and R-600a are
derived from the R-22 / R-134a tables by published volumetric-capacity ratios
(Danfoss hydrocarbon application data) — verify flammable-refrigerant designs with
the equipment manufacturer. R-717 (ammonia) is intentionally not sized: ammonia prohibits
copper and uses steel piping per ASHRAE/IIAR practice. Suction and discharge risers are checked against minimum-capacity oil-return
tables; liquid lines are checked for velocity and for subcooling to offset friction plus
static lift. Vertical risers automatically include a P-trap at the base and an inverted
trap at the top — each counted as two 90° elbows in both equivalent length and the material
list (DuPont handbook / Carrier practice; per AG 31-011, intermediate traps are unnecessary
in a properly sized riser). Fitting equivalent lengths from ASHRAE (AG 31-011 Tables 4–5). Copper temper
and lengths per the CDA Copper Tube Handbook; insulation per the Armacell AP Armaflex
submittal. Full citations: SOURCES.md in this folder.
Assumptions: Type L / ACR copper sized by OD · design ΔT 2°F suction, 1°F discharge and
liquid (A/C) · tables at 15°F superheat · verify final design against equipment
manufacturer requirements. This tool is a design aid, not a substitute for engineering
judgment.