diff --git a/projects/planner/src/app/shared/gas.properties.spec.ts b/projects/planner/src/app/shared/gas.properties.spec.ts
index 1e5a3b49..4f8a3aff 100644
--- a/projects/planner/src/app/shared/gas.properties.spec.ts
+++ b/projects/planner/src/app/shared/gas.properties.spec.ts
@@ -1,5 +1,5 @@
 import { UnitConversion } from './UnitConversion';
-import { BoundGasProperties, GasProperties } from './gas.properties';
+import { BoundGasProperties } from './gas.properties';
 
 describe('Gas properties bound', () => {
     const units: UnitConversion = new UnitConversion();
@@ -35,93 +35,3 @@ describe('Gas properties bound', () => {
         });
     });
 });
-
-describe('Gas properties calculator', () => {
-    let sut: GasProperties;
-
-    beforeEach(() => {
-        sut = new GasProperties();
-        sut.depth = 30;
-    });
-
-    describe('Air at 30 m', () => {
-        beforeEach(() => {
-            sut.tank.o2 = 21;
-        });
-
-        it('MND is 30 m', () => {
-            expect(sut.mnd).toBeCloseTo(30, 3);
-        });
-
-        it('END is 30 m', () => {
-            expect(sut.end).toBeCloseTo(30, 3);
-        });
-
-        it('Minimum depth is 0 m', () => {
-            expect(sut.minDepth).toBeCloseTo(0, 3);
-        });
-
-        it('Maximum depth (MOD) is 57 m', () => {
-            expect(sut.maxDepth).toBeCloseTo(56.986, 3);
-        });
-
-        it('Total partial pressure is depth (4 b)', () => {
-            expect(sut.totalPp).toBeCloseTo(4, 3);
-        });
-
-        it('ppO2 is 0.836', () => {
-            expect(sut.ppO2).toBeCloseTo(0.836, 3);
-        });
-
-        it('ppHe is 0', () => {
-            expect(sut.ppHe).toBeCloseTo(0, 3);
-        });
-
-        it('ppN2 is 3.164', () => {
-            expect(sut.ppN2).toBeCloseTo(3.164, 3);
-        });
-
-        it('Density is 5.15 g/l', () => {
-            expect(sut.density).toBeCloseTo(5.151972, 6);
-        });
-    });
-
-    describe('Trimix 10/70 at 30 m', () => {
-        beforeEach(() => {
-            sut.tank.o2 = 10;
-            sut.tank.he = 70;
-        });
-
-        it('MND is 123.3 m', () => {
-            expect(sut.mnd).toBeCloseTo(123.333, 3);
-        });
-
-        it('END is 2 m', () => {
-            expect(sut.end).toBeCloseTo(2, 3);
-        });
-
-        it('Minimum depth is 8 m', () => {
-            expect(sut.minDepth).toBeCloseTo(8, 3);
-        });
-
-        it('Maximum depth (MOD) is 130 m', () => {
-            expect(sut.maxDepth).toBeCloseTo(130, 3);
-        });
-
-        it('ppO2 is 0.4', () => {
-            expect(sut.ppO2).toBeCloseTo(0.4, 3);
-        });
-
-        it('ppHe is 2.8', () => {
-            expect(sut.ppHe).toBeCloseTo(2.8, 3);
-        });
-
-        it('ppN2 is 0.8', () => {
-            expect(sut.ppN2).toBeCloseTo(0.8, 3);
-        });
-
-        it('Density is 2 g/l', () => {
-            expect(sut.density).toBeCloseTo(2.0732, 6);
-        });
-    });
-});
diff --git a/projects/planner/src/app/shared/gas.properties.ts b/projects/planner/src/app/shared/gas.properties.ts
index ac836c73..a59c0f03 100644
--- a/projects/planner/src/app/shared/gas.properties.ts
+++ b/projects/planner/src/app/shared/gas.properties.ts
@@ -1,9 +1,5 @@
 import {
-    DensityAtDepth,
-    DepthConverter,
-    Gas,
-    GasMixtures,
-    Tank
+    GasProperties
 } from 'scuba-physics';
 import { TankBound } from './models';
 import { UnitConversion } from './UnitConversion';
@@ -69,71 +65,3 @@ export class BoundGasProperties {
         this.calc.depth = newValue;
     }
 }
-
-
-export class GasProperties {
-    /** in meters */
-    public depth = 0;
-    private readonly _tank = Tank.createDefault();
-    private readonly depthConverter = DepthConverter.simple();
-    private readonly densityCalc = new DensityAtDepth(this.depthConverter);
-
-    public get tank(): Tank {
-        return this._tank;
-    }
-
-    public get ppO2(): number {
-        const result = GasMixtures.partialPressure(this.depthPressure, this.gas.fO2);
-        return result;
-    }
-
-    public get ppHe(): number {
-        const result = GasMixtures.partialPressure(this.depthPressure, this.gas.fHe);
-        return result;
-    }
-
-    public get ppN2(): number {
-        const result = GasMixtures.partialPressure(this.depthPressure, this.gas.fN2);
-        return result;
-    }
-
-    public get totalPp(): number {
-        return this.depthPressure;
-    }
-
-    public get minDepth(): number {
-        const surface = this.depthConverter.surfacePressure;
-        const minDepthPressure = GasMixtures.ceiling(this.gas.fO2, surface);
-        return this.depthConverter.fromBar(minDepthPressure);
-    }
-
-    public get maxDepth(): number {
-        const maxppO2 = 1.4; // TODO add to UI
-        const maxDepthPressure = GasMixtures.mod(1.4, this.gas.fO2);
-        return this.depthConverter.fromBar(maxDepthPressure);
-    }
-
-    public get end(): number {
-        const endDepthPressure = GasMixtures.end(this.depthPressure, this.gas.fN2, this.gas.fO2);
-        return this.depthConverter.fromBar(endDepthPressure);
-    }
-
-    public get mnd(): number {
-        const narcDepthBars = 4; // TODO add to UI
-        const endDepthPressure = GasMixtures.mnd(narcDepthBars, this.gas.fN2, this.gas.fO2);
-        return this.depthConverter.fromBar(endDepthPressure);
-    }
-
-    public get density(): number {
-        const density = this.densityCalc.atDepth(this.gas, this.depth);
-        return density;
-    }
-
-    private get gas(): Gas {
-        return this.tank.gas;
-    }
-
-    private get depthPressure(): number {
-        return this.depthConverter.toBar(this.depth);
-    }
-}
diff --git a/projects/scuba-physics/src/lib/gas.properties.spec.ts b/projects/scuba-physics/src/lib/gas.properties.spec.ts
new file mode 100644
index 00000000..7a67425c
--- /dev/null
+++ b/projects/scuba-physics/src/lib/gas.properties.spec.ts
@@ -0,0 +1,91 @@
+import { GasProperties } from './gas.properties';
+
+describe('Gas properties calculator', () => {
+    let sut: GasProperties;
+
+    beforeEach(() => {
+        sut = new GasProperties();
+        sut.depth = 30;
+    });
+
+    describe('Air at 30 m', () => {
+        beforeEach(() => {
+            sut.tank.o2 = 21;
+        });
+
+        it('MND is 30 m', () => {
+            expect(sut.mnd).toBeCloseTo(30, 3);
+        });
+
+        it('END is 30 m', () => {
+            expect(sut.end).toBeCloseTo(30, 3);
+        });
+
+        it('Minimum depth is 0 m', () => {
+            expect(sut.minDepth).toBeCloseTo(0, 3);
+        });
+
+        it('Maximum depth (MOD) is 57 m', () => {
+            expect(sut.maxDepth).toBeCloseTo(56.986, 3);
+        });
+
+        it('Total partial pressure is depth (4 b)', () => {
+            expect(sut.totalPp).toBeCloseTo(4, 3);
+        });
+
+        it('ppO2 is 0.836', () => {
+            expect(sut.ppO2).toBeCloseTo(0.836, 3);
+        });
+
+        it('ppHe is 0', () => {
+            expect(sut.ppHe).toBeCloseTo(0, 3);
+        });
+
+        it('ppN2 is 3.164', () => {
+            expect(sut.ppN2).toBeCloseTo(3.164, 3);
+        });
+
+        it('Density is 5.15 g/l', () => {
+            expect(sut.density).toBeCloseTo(5.151972, 6);
+        });
+    });
+
+    describe('Trimix 10/70 at 30 m', () => {
+        beforeEach(() => {
+            sut.tank.o2 = 10;
+            sut.tank.he = 70;
+        });
+
+        it('MND is 123.3 m', () => {
+            expect(sut.mnd).toBeCloseTo(123.333, 3);
+        });
+
+        it('END is 2 m', () => {
+            expect(sut.end).toBeCloseTo(2, 3);
+        });
+
+        it('Minimum depth is 8 m', () => {
+            expect(sut.minDepth).toBeCloseTo(8, 3);
+        });
+
+        it('Maximum depth (MOD) is 130 m', () => {
+            expect(sut.maxDepth).toBeCloseTo(130, 3);
+        });
+
+        it('ppO2 is 0.4', () => {
+            expect(sut.ppO2).toBeCloseTo(0.4, 3);
+        });
+
+        it('ppHe is 2.8', () => {
+            expect(sut.ppHe).toBeCloseTo(2.8, 3);
+        });
+
+        it('ppN2 is 0.8', () => {
+            expect(sut.ppN2).toBeCloseTo(0.8, 3);
+        });
+
+        it('Density is 2 g/l', () => {
+            expect(sut.density).toBeCloseTo(2.0732, 6);
+        });
+    });
+});
diff --git a/projects/scuba-physics/src/lib/gas.properties.ts b/projects/scuba-physics/src/lib/gas.properties.ts
new file mode 100644
index 00000000..692a516e
--- /dev/null
+++ b/projects/scuba-physics/src/lib/gas.properties.ts
@@ -0,0 +1,71 @@
+import { DensityAtDepth } from './GasDensity';
+import { Gas, GasMixtures } from './Gases';
+import { Tank } from './Tanks';
+import { DepthConverter } from './depth-converter';
+
+export class GasProperties {
+    /** in meters */
+    public depth = 0;
+    private readonly _tank = Tank.createDefault();
+    private readonly depthConverter = DepthConverter.simple();
+    private readonly densityCalc = new DensityAtDepth(this.depthConverter);
+
+    public get tank(): Tank {
+        return this._tank;
+    }
+
+    public get ppO2(): number {
+        const result = GasMixtures.partialPressure(this.depthPressure, this.gas.fO2);
+        return result;
+    }
+
+    public get ppHe(): number {
+        const result = GasMixtures.partialPressure(this.depthPressure, this.gas.fHe);
+        return result;
+    }
+
+    public get ppN2(): number {
+        const result = GasMixtures.partialPressure(this.depthPressure, this.gas.fN2);
+        return result;
+    }
+
+    public get totalPp(): number {
+        return this.depthPressure;
+    }
+
+    public get minDepth(): number {
+        const surface = this.depthConverter.surfacePressure;
+        const minDepthPressure = GasMixtures.ceiling(this.gas.fO2, surface);
+        return this.depthConverter.fromBar(minDepthPressure);
+    }
+
+    public get maxDepth(): number {
+        const maxppO2 = 1.4; // TODO add to UI
+        const maxDepthPressure = GasMixtures.mod(1.4, this.gas.fO2);
+        return this.depthConverter.fromBar(maxDepthPressure);
+    }
+
+    public get end(): number {
+        const endDepthPressure = GasMixtures.end(this.depthPressure, this.gas.fN2, this.gas.fO2);
+        return this.depthConverter.fromBar(endDepthPressure);
+    }
+
+    public get mnd(): number {
+        const narcDepthBars = 4; // TODO add to UI
+        const endDepthPressure = GasMixtures.mnd(narcDepthBars, this.gas.fN2, this.gas.fO2);
+        return this.depthConverter.fromBar(endDepthPressure);
+    }
+
+    public get density(): number {
+        const density = this.densityCalc.atDepth(this.gas, this.depth);
+        return density;
+    }
+
+    private get gas(): Gas {
+        return this.tank.gas;
+    }
+
+    private get depthPressure(): number {
+        return this.depthConverter.toBar(this.depth);
+    }
+}
diff --git a/projects/scuba-physics/src/public-api.ts b/projects/scuba-physics/src/public-api.ts
index f5618583..a5146e14 100644
--- a/projects/scuba-physics/src/public-api.ts
+++ b/projects/scuba-physics/src/public-api.ts
@@ -13,6 +13,7 @@ export * from './lib/DepthLevels';
 export * from './lib/Diver';
 export * from './lib/Gases';
 export * from './lib/GasDensity';
+export * from './lib/gas.properties';
 export * from './lib/NitroxCalculator';
 export * from './lib/Options';
 export * from './lib/OtuCalculator';