ASME PTC 10-1997 (2014) — Performance Test Code on Compressors and Exhausters

🔧 ASME PTC 10-1997 (2014) is the core performance test code for axial and centrifugal compressors and exhausters in the ASME Performance Test Codes family. Descending from the 1965 edition and completely rewritten in 1997, then reaffirmed in 2014, it defines explicit test procedures to determine the thermodynamic performance of a compressor or exhauster doing work on a gas of known or measurable properties under specified conditions. Its goal is the highest level of accuracy consistent with current engineering knowledge and practice, while providing rules to estimate the uncertainty of each individual test. PTC 10 is the common technical basis for shop acceptance tests, field acceptance tests, and performance verification for both suppliers and purchasers.

1. Object and Scope 📌

The Code covers single- or multiple-casing axial or centrifugal compressors, or combinations thereof, with one or more stages of compression per casing, as well as machines with externally piped intercoolers and interstage side load inlets or outlets. It provides instructions on test arrangement and instrumentation, test procedure, and methods for evaluation and reporting, establishing the following quantities (corrected as necessary to the specified conditions):

• Quantity of gas delivered (flow capacity);
• Pressure rise produced (pressure ratio);
• Head (polytropic or isentropic);
• Shaft power required;
• Efficiency (polytropic and isentropic);
• Surge point and choke point.

Other than methods for calculating mechanical power losses, the Code does not cover rotor dynamics or other mechanical performance parameters. Typical gases handled are air, its constituents, and various hydrocarbons. Internally cooled compressors are included provided test conditions are held nearly identical to specified conditions.

2. Test Types: Type 1 and Type 2 🔬

To balance test cost and result accuracy, the Code defines two test types. Type 1 tests are run with test conditions essentially identical to specified conditions, with very small permissible deviations (per Table 3.1), so the results apply directly. Type 2 tests permit larger deviations — including the use of a substitute test gas (for example air or nitrogen instead of a hydrocarbon) — but the results must be converted to specified conditions using the dimensionless-parameter method of Section 5.

Computations are performed on the “section” as the smallest element: complex machines are decomposed into sections, and section results are combined to obtain overall machine performance, which handles multiple inlets, outlets, intercoolers, and sidestream arrangements.

3. Instruments and Methods of Measurement 🎛️

Section 4 specifies inlet and discharge measurement arrangements. Closed-loop and open-loop schematics are provided, including straighteners, equalizers, and inlet/discharge nozzles for both subcritical and critical flow. Key measurements include:

• Pressure: total and static pressure at inlet and discharge, per ASME PTC 19.2;
• Temperature: total temperature at inlet and discharge, per ASME PTC 19.3;
• Flow: nozzles, orifice plates, and other primary elements per ASME PTC 19.5;
• Gas composition: gas analysis per ASME PTC 19.10 when needed to establish gas constant and specific heat ratio;
• Speed and power: tachometers, torque meters, or dynamometers for shaft power.

4. Computation of Results 🧮

Section 5 defines the computation methods. Dimensionless parameters for ideal-gas and real-gas cases are given (Tables 5.1, 5.2), including flow coefficient, head coefficients (polytropic and isentropic), total work input coefficient (Table 5.3), and efficiency definitions. Real-gas calculations use the Schultz compressibility correction (functions X and Y versus reduced pressure), with Appendix B providing gas-mixture property methods. The general conversion steps are:

• Compute each section’s actual performance from measured data;
• Convert actual performance to dimensionless form (with corrections for Mach and Reynolds number departures);
• Reconstruct the specified performance from dimensionless parameters at specified conditions;
• For multi-section machines, convert section by section and combine using intercooler and sidestream boundary conditions.

The Code also covers mechanical power loss handling and determination of surge and choke points. Test points in uncertain regions of the curve (bracketed test points) are treated per Appendix C.4.

5. Test Report and Uncertainty 📋

Section 6 defines the content of a test report: equipment description, test conditions, instrument list with calibrations, raw data, computed results, correction process, and conclusions. The Code emphasizes that ASME Performance Test Codes do not specify how to compare results with contractual guarantees; the parties should agree before starting the test — preferably before signing the contract — on the comparison method. Uncertainty analysis can be performed with software developed by the Committee; the Code provides rules rather than a single universal uncertainty value for all tests.

6. Engineering Practice Essentials 🛠️

• 🔍 Pre-test review: clarify guarantee clauses, fix the test type and instrument accuracy class, and verify the field can stay within permissible deviations;
• 🔧 Closed loop: when open-loop straight-run requirements cannot be met on site, prefer a closed-loop test rig; check loop cooler capacity and system tightness;
• 📊 Substitute gas: air or nitrogen is often used when hydrocarbons are unavailable or unsafe, but verify property departures stay within the Code limits (Table 3.3) and account for added uncertainty;
• 📋 Data averaging: control reading fluctuations per Table 3.4, average over a suitable period, and avoid taking points near surge or choke boundaries.

7. Frequently Asked Questions ❓