Tank Chart Calculator
Understanding Tank Charts and Volume Calculation
A Tank Chart (also known as a strapping table or calibration chart) is essential for converting a linear measurement of liquid depth into a volumetric quantity. In industrial, agricultural, and residential settings, fluid is often stored in cylindrical tanks. Because the relationship between depth and volume is not linear for horizontal cylinders, a simple ruler measurement requires complex calculation to determine how much liquid is actually inside.
This calculator acts as a dynamic tank chart, allowing you to generate precise volume data based on the physical dimensions of your storage vessel and the current dip level.
Why Can't I Just Multiply Depth by Area?
For a Vertical Cylinder (like a silo or upright water tank), you can indeed multiply the circular area of the base by the depth of the liquid. The relationship is linear: if the tank is half full by depth, it is half full by volume.
However, for a Horizontal Cylinder (like a fuel truck or underground propane tank), the geometry changes. The cross-section of the liquid is a circular segment. At the bottom and top of the tank, a small change in depth adds very little volume. At the middle of the tank (the widest point), a small change in depth adds a significant amount of volume. This calculator uses geometric trigonometry to solve for the area of the wetted segment and multiplies it by the length of the tank.
Formulas Used
To ensure accuracy, we utilize the following geometric formulas:
1. Vertical Cylinder
Calculation is straightforward based on the radius (r) and fill depth (d):
- Volume = π × r² × d
2. Horizontal Cylinder
This requires calculating the area of the circular segment filled with liquid:
- Radius (r) = Diameter / 2
- Area = r²cos¹((r-d)/r) – (r-d)√(2rd – d²)
- Volume = Area × Length
Note: This tool assumes flat ends for the tank. If your tank has hemispherical or elliptical heads, the volume will be slightly higher than calculated here.
Common Applications
- Diesel & Fuel Storage: Monitoring inventory in horizontal bulk tanks.
- Water Treatment: Calculating chemical dosing based on current tank volume.
- Propane Tanks: Estimating remaining heating fuel based on gauge percentage or dip stick.
- Septic Systems: determining pump-out requirements.