diff --git a/src/main/java/neqsim/thermo/system/SystemInterface.java b/src/main/java/neqsim/thermo/system/SystemInterface.java
index 8539d9213..00f63df4e 100644
--- a/src/main/java/neqsim/thermo/system/SystemInterface.java
+++ b/src/main/java/neqsim/thermo/system/SystemInterface.java
@@ -2612,4 +2612,24 @@ public void setImplementedTemperatureDeriativesofFugacity(
    * @return a {@link java.lang.String} object
    */
   public String toCompJson();
+
+  /**
+   * <p>
+   * setForceSinglePhase - force the fluid to be single phase of type as spesified by phasetype
+   * input
+   * </p>
+   *
+   * @param phasetype a {@link neqsim.thermo.phase.PhaseType} object
+   */
+  public void setForceSinglePhase(PhaseType phasetype);
+
+  /**
+   * <p>
+   * setForceSinglePhase - force the fluid to be single phase of type as spesified by phasetype
+   * input. phasetypename can be GAS, OIL and AQUEOUS
+   * </p>
+   *
+   * @param phasetypename a {@link java.lang.String} object
+   */
+  public void setForceSinglePhase(String phasetypename);
 }
diff --git a/src/main/java/neqsim/thermo/system/SystemThermo.java b/src/main/java/neqsim/thermo/system/SystemThermo.java
index 8ba0d9bbe..608b65350 100644
--- a/src/main/java/neqsim/thermo/system/SystemThermo.java
+++ b/src/main/java/neqsim/thermo/system/SystemThermo.java
@@ -5071,4 +5071,20 @@ public String toCompJson() {
     return new GsonBuilder().create()
         .toJson(new neqsim.processsimulation.util.monitor.FluidComponentResponse(this));
   }
+
+  /** {@inheritDoc} */
+  @Override
+  public void setForceSinglePhase(PhaseType phasetype) {
+    this.init(0);
+    this.setNumberOfPhases(1);
+    this.setMaxNumberOfPhases(1);
+    this.setForcePhaseTypes(true);
+    this.setPhaseType(0, phasetype);
+  }
+
+  /** {@inheritDoc} */
+  @Override
+  public void setForceSinglePhase(String phasetype) {
+    setForceSinglePhase(PhaseType.byName(phasetype));
+  }
 }
diff --git a/src/test/java/neqsim/thermo/system/SystemThermoTest.java b/src/test/java/neqsim/thermo/system/SystemThermoTest.java
index bdca62a47..b70e78b43 100644
--- a/src/test/java/neqsim/thermo/system/SystemThermoTest.java
+++ b/src/test/java/neqsim/thermo/system/SystemThermoTest.java
@@ -6,6 +6,7 @@
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import neqsim.thermo.ThermodynamicConstantsInterface;
+import neqsim.thermo.phase.PhaseType;
 import neqsim.thermodynamicoperations.ThermodynamicOperations;
 
 class SystemThermoTest extends neqsim.NeqSimTest {
@@ -118,4 +119,32 @@ void testDisplay() {
     SystemEos s = new SystemPrEos();
     s.display();
   }
+
+  @Test
+  void TESTsetForceSinglePhase() {
+    testSystem = new neqsim.thermo.system.SystemPrEos(298.0, 10.0);
+    testSystem.addComponent("nitrogen", 0.01);
+    testSystem.addComponent("CO2", 0.01);
+    testSystem.addComponent("methane", 0.68);
+    testSystem.setMixingRule("classic");
+    ThermodynamicOperations testOps = new ThermodynamicOperations(testSystem);
+    testOps.TPflash();
+    testSystem.initProperties();
+
+
+    double density = testSystem.getDensity("kg/m3");
+
+    testSystem.setForceSinglePhase(PhaseType.GAS);
+    testSystem.initProperties();
+
+    assertEquals(density, testSystem.getDensity("kg/m3"), 1e-4);
+
+    testSystem.setForceSinglePhase("GAS");
+    testOps.TPflash();
+    testSystem.initProperties();
+
+    assertEquals(density, testSystem.getDensity("kg/m3"), 1e-4);
+
+
+  }
 }