ASME PTC 10 Compressor Performance Calculator — Shaft Power, Isentropic Efficiency & Discharge Temperature
ASME PTC 10 — Performance Test Code on Compressors and Exhausters
ASME PTC 10-1997 (Performance Test Code on Compressors and Exhausters) is the ASME B&PV code section that defines the accepted engineering method for measuring and calculating the thermodynamic performance of compressors — centrifugal, axial and positive-displacement types. It establishes the governing definitions of isentropic and polytropic specific work, isentropic efficiency, the temperature and pressure measurement conventions for acceptance testing, and the allowable test gas substitution rules when the specified process gas cannot be used during the performance test. PTC 10 is the standard vendors and operators cite when a compressor is contracted with a power or efficiency guarantee.
MechanixCalc implements the ASME PTC 10 thermodynamic method directly in your browser: enter the suction and discharge conditions, the gas, the number of stages and the isentropic efficiency, and the tool returns shaft power, actual discharge temperature, overall isentropic efficiency, volumetric flow rate and motor drive sizing in one pass. Multi-stage configurations with intercooling resolve the per-stage temperatures, pressures and work split automatically. A P-V and T-s thermodynamic diagram, a reciprocating P-V indicator loop and a centrifugal surge/choke operating map provide the visual context that vendors and reviewers expect.
Calculators that implement ASME PTC 10
What ASME PTC 10 covers
- Isentropic (adiabatic) specific work and shaft power — derived from the steady-flow energy equation for a reversible adiabatic process using the inlet temperature, the overall pressure ratio and the gas ratio of specific heats γ
- Isentropic efficiency — the ratio of ideal isentropic work to actual shaft work, including the ASME PTC 10 like-for-like comparison basis to prevent η > 100 % in intercooled machines
- Actual discharge temperature — isentropic temperature rise scaled by the isentropic efficiency, giving the true exit state of the gas
- Multi-stage compression with perfect or partial intercooling — equal stage pressure ratios for minimum total work; per-stage T, P and work breakdown; intercooler heat duty and cooling-water demand
- Reciprocating compressor P-V indicator loop — polytropic compression and re-expansion curves, clearance-volume volumetric efficiency and indicated work per cycle on the induced (not swept) volume, consistent with ASME PTC 10 conventions
- Centrifugal compressor surge margin and choke margin with operating-point map (engineering-estimate panel, marked with EstimateBadge; verify against manufacturer's test data)
Governing formulas
W_is = (γ / (γ − 1)) · R · T₁ · ( (P₂/P₁)^((γ−1)/γ) − 1 )where W_is = isentropic specific work (kJ/kg); γ = ratio of specific heats Cp/Cv (dimensionless); R = specific gas constant (kJ/kg·K); T₁ = absolute inlet temperature (K); P₂/P₁ = overall pressure ratio (dimensionless). Shaft power P_shaft = ṁ · W_is / η_is, where ṁ = mass flow rate (kg/s) and η_is = isentropic efficiency (dimensionless)
T₂ = T₁ + (T₂ₛ − T₁) / η_is where T₂ₛ = T₁ · (P₂/P₁)^((γ−1)/γ)where T₂ = actual discharge temperature (K); T₂ₛ = isentropic discharge temperature (K); T₁ = absolute inlet temperature (K); P₂/P₁ = pressure ratio; γ = ratio of specific heats; η_is = isentropic efficiency (dimensionless, 0–1)
η_v = 1 − c · ( (P₂/P₁)^(1/n) − 1 )where η_v = volumetric efficiency (dimensionless); c = clearance ratio = V_clearance / V_displacement (dimensionless); P₂/P₁ = pressure ratio; n = polytropic index (dimensionless). The indicated work per cycle equals the enclosed area of the P-V loop computed on the induced volume (BDC − end of re-expansion), which excludes the shuttle work of the clearance gas
Frequently asked questions
What is ASME PTC 10 used for?
ASME PTC 10 (Performance Test Code on Compressors and Exhausters) defines the accepted engineering method for measuring and verifying the thermodynamic performance of compressors. It establishes how to calculate isentropic specific work, isentropic efficiency and shaft power, and it specifies the test procedures — including allowable substitute gas rules — used when a compressor is contracted with a power or efficiency guarantee. It applies to centrifugal, axial and positive-displacement compressors.
What is the difference between ASME PTC 10 and ISO 1217?
ASME PTC 10 covers all compressor types (centrifugal, axial and positive-displacement) and is primarily a performance-test code — it governs how a factory or field test is conducted and the acceptance criteria applied to a contract guarantee. ISO 1217 applies specifically to displacement compressors (reciprocating and screw) and focuses on acceptance-test measurement methods and tolerances for that sub-class. The core isentropic thermodynamic method is consistent between the two standards; MechanixCalc implements both.
Does MechanixCalc implement the full ASME PTC 10 method?
Yes — the compressor analysis calculator uses the ASME PTC 10 isentropic specific-work formula, computes shaft power as ṁ·W_is/η_is, derives the actual discharge temperature from the isentropic temperature rise, and reports overall isentropic efficiency on the correct like-for-like basis (avoiding the η > 100 % artefact that arises in intercooled machines if the single-stage isentropic ideal is compared against the intercooled actual work). The governing method is shown in the generated PDF report.
How does multi-stage intercooling affect compressor power under ASME PTC 10?
Compression work is proportional to the absolute inlet temperature. With perfect intercooling between stages the gas is cooled back to the suction temperature, so each stage operates from the same low inlet temperature and the total work is minimised. The equal-stage-pressure-ratio split (r_stage = (P₂/P₁)^(1/N)) is the thermodynamically optimal arrangement for minimum total shaft power. The MechanixCalc compressor calculator shows the per-stage power breakdown and the total saving relative to single-stage compression for up to four stages.
Is the ASME PTC 10 compressor calculator free?
You can use it during a free 30-minute preview with no sign-up required, and a free 14-day account trial unlocks every MechanixCalc calculator with no credit card. The branded PDF engineering report and saved calculations are part of a paid plan.
Related standards
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