Subsea calculator
Depth to pressure calculator
Convert a working depth into the pressure a housing, penetrator or foam block has to withstand, in bar, psi, MPa and atmospheres, for seawater or fresh water.
This is an estimate for early design work. It uses the method and assumptions shown below the result. It leaves out some things a real build has to allow for (see “Assumptions and limits”) and it does not replace an engineer's sign-off. For a figure you can build to, send us the requirement.
Result
Why it matters
Depth ratings are pressure ratings.
A part rated to 300 m is rated to the pressure of 300 m of water. Once you work in pressure, you can compare an acrylic tube rated in metres with a foam grade rated in MPa and a test chamber rated in bar.
The rule of thumb is one bar for every ten metres. That is fine for conversation, but in seawater it is about 0.5% low. For a specification, use the calculated figure: at 1,000 m the rule of thumb is more than five bar short.
How it is calculated
Hydrostatic pressure.
Gauge pressure is the weight of the water above a point: p = ρ × g × h, where ρ is the water density, g is standard gravity (9.80665 m/s²) and h is the depth. Absolute pressure adds one atmosphere. That is what an absolute sensor reads, and it is the figure to use for the pressure difference across a housing wall.
Seawater is taken as 1025 kg/m³ and fresh water as 1000 kg/m³. Real seawater density changes with temperature, salinity and, very slightly, depth. For design margin, use the higher density.
Related
Other calculators and guides.
Request a quotation
Tell us what you need.
Send the items or requirement, the quantity, the application it is for and when you need it. We reply within one working day.
Request a QuotationBrowse the parts shop
Or call +91 97028 20020.