1. What is Surface Air Consumption Rate?

Surface Air Consumption (SAC) rate is a measure of how much air a diver consumes per minute at the surface. It's used to estimate air consumption at depth and plan dive durations and gas requirements.

2. How Does the Calculator Work?

The calculator uses the SAC formula:

Where:

• \( SAC \) — Surface Air Consumption (ft³/min)
• \( \text{Volume Used} \) — Tank PSI Drop × Tank Volume / 14.7 (ft³)
• \( \text{Time} \) — Dive time (min)
• \( \text{Avg Depth} \) — Average depth during dive (fsw)

Explanation: The formula calculates air consumption at surface pressure, then adjusts for depth to determine actual consumption during the dive.

3. Importance of SAC Calculation

Details: Knowing your SAC rate is crucial for dive planning, determining how long your air supply will last at different depths, and ensuring safe diving practices.

4. Using the Calculator

Tips: Enter tank PSI drop, tank volume in cubic feet, dive time in minutes, and average depth in feet of seawater. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical SAC rate for divers?
A: SAC rates vary by experience and exertion level. Beginners: 0.75-1.0 ft³/min, experienced: 0.5-0.75 ft³/min, technical divers: 0.3-0.5 ft³/min.

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

Q3: Why divide by 14.7 in the volume calculation?
A: This converts PSI to atmospheres, as 14.7 psi equals 1 atmosphere at sea level.

Q4: When should I recalculate my SAC rate?
A: Recalculate periodically, especially after changes in fitness, equipment, or diving conditions. Also recalculate for different types of diving.

Q5: Can SAC rate be used for different tank sizes?
A: Yes, SAC rate is independent of tank size as it measures consumption rate, not total consumption.