Standard_EN16726 and Standard_EN16723 provide deterministic screens over a NeqSim gas composition. They are useful for checking the current library behavior and for building a project-owned quality workflow. They do not reproduce sampling, laboratory analysis, uncertainty, national annexes, or the complete requirements of a licensed standard.

The two classes are coupled: EN 16723 Part 1 delegates its base-gas checks to an internal Standard_EN16726 instance. Use them only after validating the exact class behavior below against the governing contract and standards editions.

Complete Java 8 example

The fixture is a normalized dry biomethane composition. Assertions deliberately use only result keys implemented by the current classes.

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import neqsim.standards.gasquality.Standard_EN16723;
import neqsim.standards.gasquality.Standard_EN16726;
import neqsim.thermo.system.SystemInterface;
import neqsim.thermo.system.SystemSrkEos;
import neqsim.thermodynamicoperations.ThermodynamicOperations;

public final class EnGasQualityExample {
  private static final Logger logger = LogManager.getLogger(EnGasQualityExample.class);

  private EnGasQualityExample() {}

  public static void main(String[] args) {
    SystemInterface gas = new SystemSrkEos(288.15, 1.01325);
    gas.addComponent("methane", 0.964995);
    gas.addComponent("CO2", 0.020000);
    gas.addComponent("nitrogen", 0.015000);
    gas.addComponent("oxygen", 0.000005);
    gas.setMixingRule("classic");
    new ThermodynamicOperations(gas).TPflash();

    Standard_EN16726 networkGas = new Standard_EN16726(gas);
    networkGas.setNetworkType("transmission");
    networkGas.calculate();

    double wobbeIndex = networkGas.getValue("WobbeIndex");
    double carbonDioxide = networkGas.getValue("CO2");
    assert Double.isFinite(wobbeIndex);
    assert wobbeIndex >= networkGas.getWobbeIndexMin();
    assert wobbeIndex <= networkGas.getWobbeIndexMax();
    assert Math.abs(carbonDioxide - 2.0) < 1.0e-9;
    assert "MJ/m3".equals(networkGas.getUnit("WobbeIndex"));
    assert "mol%".equals(networkGas.getUnit("CO2"));
    assert networkGas.isOnSpec();

    Standard_EN16723 gridInjection = new Standard_EN16723(gas, 1);
    gridInjection.calculate();
    assert Math.abs(gridInjection.getValue("methane") - 96.4995) < 1.0e-9;
    assert Math.abs(gridInjection.getValue("totalInerts") - 3.5) < 1.0e-9;
    assert gridInjection.isOnSpec();

    Standard_EN16723 vehicleFuel = new Standard_EN16723(gas, 2);
    vehicleFuel.calculate();
    assert vehicleFuel.isOnSpec();

    double publishedSiloxaneLimit = gridInjection.getValue("siloxaneLimit");
    assert Math.abs(publishedSiloxaneLimit - 0.3) < 1.0e-12;

    logger.info("EN 16726 screen: WI={} MJ/m3, CO2={} mol%, onSpec={}", wobbeIndex,
        carbonDioxide, networkGas.isOnSpec());
    logger.info("EN 16723 screens: Part 1={}, Part 2={}, siloxane limit={} mg/m3",
        gridInjection.isOnSpec(), vehicleFuel.isOnSpec(), publishedSiloxaneLimit);
  }
}

The final siloxane value is an embedded limit, not a calculated contaminant concentration. The example asserts that distinction in the regression test.

Standard_EN16726 implementation boundary

calculate() delegates calorific properties to Standard_ISO6976 using a 0 °C volume reference and a 25 °C combustion-energy reference. It then reads selected overall mole fractions from phase 0.

Result key Reported unit Current calculation
WobbeIndex or WI MJ/m3 Superior Wobbe index from the internal ISO 6976 calculation
GCV or grossCalorificValue MJ/m3 Superior calorific value from the internal ISO 6976 calculation
relativeDensity dimensionless Relative density from the internal ISO 6976 calculation
CO2, O2, H2 mol% Phase-0 overall mole fraction multiplied by 100
H2S mg/m3 Approximate H2S compound concentration at 0 °C and 1 atm
totalSulfur mg/m3 Implementation proxy that adds approximate H2S and COS compound concentrations
water mg/m3 Approximate water concentration at 0 °C and 1 atm

The two-argument getter ignores its unit argument. Use the fixed units returned by getUnit(...); it does not convert results. Unknown result keys currently fall back to the Wobbe index, so validate keys before calling the generic getter.

isOnSpec() applies the class’s embedded Wobbe-index, relative-density, CO2, H2S, total-sulfur, O2, and H2 limits. It does not calculate or check water dew point, hydrocarbon dew point, mercaptan sulfur, sampling, measurement uncertainty, or a complete national specification. The calculated water concentration is not part of the boolean result.

The exact string "transmission" selects the transmission O2 limit. Every other string selects the distribution limit, so validate caller input before invoking setNetworkType(...). setH2Limit(...) changes only the embedded H2 screen and must be tied to a controlled project requirement.

Standard_EN16723 implementation boundary

Part 1 checks CO2, O2, H2, total inerts, and the complete boolean returned by the internal EN 16726 screen. Part 2 checks only CO2, O2, and methane content. Pass only 1 or 2: the current implementation treats every value other than 1 as Part 2.

Supported composition-result keys are methane, methaneContent, CO2, O2, H2, totalInerts, WobbeIndex, and WI. The class also exposes siloxaneLimit, ammoniaLimit, and amineLimit as constants. It does not calculate those contaminants. Fluorine and chlorine limits exist internally but have no public result key. None of these trace-contaminant limits participates in isOnSpec().

As with EN 16726, the two-argument getter performs no conversion and an unknown key falls back to the Wobbe index. Retrieve the coupled base screen with getEN16726() when the individual EN 16726 results are required.

Fail-closed project workflow

  1. Normalize and validate the molar composition before constructing either class.
  2. Check that required trace species are represented by qualified measurements; an absent component is treated as zero by these implementations.
  3. Call calculate(), then reject non-finite or implausible values before using isOnSpec(). Calculation exceptions are logged internally and are not rethrown.
  4. Compare every required property with a version-controlled project limit. Add measured contaminants, dew points, uncertainty, rounding, and exception handling outside these classes.
  5. Record the NeqSim version, EOS, composition basis, result key, fixed unit, reference conditions, selected part or network type, governing edition, national requirements, and accountable reviewer.

Do not report a passing boolean as EN conformity. It is evidence that the properties implemented by this exact NeqSim class satisfy its embedded screening limits.