Air Tank Runtime Calculator — Train Horn Blasts Per Tank
How many 2-second blasts can you get from a 3-gallon tank at 150 PSI? Browser-side calculator using Boyle's law for tank volume, max PSI, min PSI, and horn CFM.
Standard kits: 0.8 / 1 / 2 / 3 / 5 gal
A short toot is 1 sec; long blast ~3 sec
Typical cut-out: 150 PSI
Below ~90 PSI most horns sound weak
Horn class
Your tank holds about
2blasts
of 2 sec each before the compressor has to catch up. That's 4.5 sec of continuous horn time total.
Blast-by-blast
Compressor recovery between blasts not included — run the Compressor Recovery calculator for that.
The math
- Usable air (free-air equivalent)
- 0.91 ft³
- Horn air consumption
- 12 SCFM
- Pressure drop window
- 150 → 100 PSI
- Air per blast
- 0.400 ft³
Formula: V_usable = V_tank × (P_full − P_min) / 14.7, then blasts = V_usable / (SCFM × t / 60). Assumes isothermal expansion, no compressor running during the blast, and an idle horn valve (no leaks). Real numbers run 10–20% lower because of piping loss and temperature drop.
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