Calculated Result
Calculator Inputs
Results and Analysis
Example Data Table
| Case | Measured Density (kg/m³) | Measured Temp (°C) | Reference Density (kg/m³) | Reference Temp (°C) | Estimated Specific Gravity |
|---|---|---|---|---|---|
| A | 682 | 25 | 999.016 | 15.6 | 0.6923 |
| B | 610 | 10 | 998.200 | 20 | 0.6133 |
| C | 720 | 5 | 999.016 | 15.6 | 0.7170 |
| D | 1.85 | 77 | 1.225 | 15 | 1.4524 |
Formula Used
The calculator uses a temperature-corrected density ratio.
1. Temperature conversion: Convert the measured temperature and reference temperature to degrees Celsius.
2. Corrected ammonia density: ρa,corr = ρa,meas / (1 + αa × (Tmeas - Tref))
3. Corrected reference density: ρr,corr = ρr / (1 + αr × (Tmeas - Tref))
4. Specific gravity: SG = ρa,corr / ρr,corr
When temperature effects are negligible, set both expansion coefficients to zero. The calculator then becomes a direct density ratio between ammonia and the chosen reference fluid.
How to Use This Calculator
- Enter the measured ammonia density and choose the matching density unit.
- Select the reference fluid. Choose custom if your process standard uses another reference density.
- Provide the measured temperature and the target reference temperature.
- Adjust the volumetric expansion coefficients when you have plant data, lab values, or standard handbook values.
- Press Calculate Specific Gravity to show the result above the form and again in the analysis section.
- Review the graph to see how specific gravity changes across a density sweep around your entered value.
- Use the CSV button for spreadsheet work and the PDF button for reports or field documentation.
FAQs
1. What does ammonia specific gravity mean?
It is the ratio of ammonia density to a chosen reference density, commonly water. A value below one means ammonia is less dense than the reference fluid under the stated conditions.
2. Why does temperature matter in specific gravity calculations?
Density changes with temperature. If ammonia warms or cools, its volume changes and the measured density shifts. Correcting to a common reference temperature improves consistency between measurements.
3. Can I compare ammonia against air instead of water?
Yes. Select the air reference or enter a custom reference density. That can be useful when reviewing gas-phase comparisons or process data that defines relative density differently.
4. Is the expansion-coefficient correction exact?
No. It is a practical linear approximation. High-accuracy work may require equation-of-state data, composition corrections, pressure corrections, or laboratory density values at the exact operating condition.
5. Which density unit should I use?
Use whichever matches your measurement source. The calculator converts kg/m³, g/cm³, and lb/ft³ internally. Keeping units consistent prevents conversion mistakes during reporting and hand checks.
6. When should I use a custom reference density?
Use a custom value when your specification, textbook, plant standard, or experiment defines a different reference basis. That makes the reported specific gravity align with your governing method.
7. What does a specific gravity above one mean here?
It means the corrected ammonia density is greater than the chosen reference density. This usually happens only when the reference is something lighter than water, such as air.
8. Can this calculator replace laboratory testing?
No. It helps estimate and normalize data quickly. Laboratory measurements and validated process standards remain the right choice for custody transfer, compliance, or critical engineering decisions.