1. What is Surface Air Consumption (SAC)?

Surface Air Consumption (SAC) rate measures how much air a diver uses per minute at the surface. It's a crucial metric for dive planning, helping divers estimate their air consumption at different depths and plan their dives safely.

2. How Does the Calculator Work?

The calculator uses the SAC equation:

Where:

• \( start \) — Starting tank pressure (psi)
• \( end \) — Ending tank pressure (psi)
• \( time \) — Dive time (minutes)
• \( ATA \) — Atmospheres absolute (depth pressure)

Explanation: The equation calculates air consumption rate by accounting for the pressure difference over time, normalized to surface pressure.

3. Importance of SAC Calculation

Details: Knowing your SAC rate is essential for proper dive planning, estimating air consumption at different depths, ensuring you have enough air for the dive, and managing emergency situations.

4. Using the Calculator

Tips: Enter starting and ending tank pressures in psi, dive time in minutes, and ATA (depth pressure). All values must be valid (pressures > 0, time > 0, ATA ≥ 1).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical SAC rate for divers?
A: SAC rates vary widely among divers. Beginners typically have rates of 25-35 psi/min, while experienced divers may have rates of 15-25 psi/min.

Q2: How does depth affect air consumption?
A: Air consumption increases with depth due to increased pressure. At 2 ATA (33 feet/10 meters), you consume air twice as fast as at the surface.

Q3: How can I improve my SAC rate?
A: Improve buoyancy control, reduce exertion, streamline equipment, practice proper breathing techniques, and gain more diving experience.

Q4: Should I use metric or imperial units?
A: This calculator uses imperial units (psi). For metric (bar), the calculation is identical but units differ.

Q5: When should I recalculate my SAC rate?
A: Recalculate periodically as your skills improve, when using new equipment, or if your fitness level changes significantly.