Convert pressure: ATA, bar, kPa and PSI.
What does 1.5 ATA mean, and is it the same as bar? Convert any pressure unit instantly and read in plain language what the numbers mean.
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What does ATA mean?
ATA stands for atmosphere absolute: the total pressure, including the air pressure around us. At sea level that is 1.0 ATA. In a hyperbaric chamber at 1.5 ATA the pressure is one and a half times that at sea level: half an atmosphere extra, comparable to about five metres under water.
Are ATA, atm and bar the same?
Almost. 1 ATA is exactly one standard atmosphere (atm) absolute: 101.325 kPa. One bar is 100 kPa, so 1 atm is 1.013 bar. For a hyperbaric chamber the difference is small (2.0 ATA is 2.03 bar absolute), but it matters when you compare spec sheets. A note on manuals: some manufacturers wrongly use atm for gauge pressure (0.5 atm for a 1.5 ATA chamber), and older type plates call absolute pressure ata and gauge pressure atü.
Absolute or gauge pressure?
This is the most common pitfall. Many gauges and spec sheets show gauge pressure: only the part above normal air pressure, in bar(g), kPa(g) or psig. A chamber with 0.5 bar gauge works at about 1.5 ATA. A chamber with 4 psi gauge, a common US rating, works at about 1.27 ATA. Always compare absolute with absolute.
Working pressure or test pressure?
The working pressure is the pressure a chamber works at during a training. The test pressure is what the manufacturer tests it at, deliberately well above that. A chamber tested at 2.4 ATA may work at 1.5 ATA, for example. When you compare, look at the working pressure. Valves and type plates often state it in kilopascal gauge, for example limited to 50 kPa, tested up to 150 kPa: a working pressure of about 1.5 ATA and a test pressure of about 2.5 ATA.
Which pressure suits you?
That depends on what you want, how often you train and how much space and supervision there is. Soft chambers work at 1.3 to 1.5 ATA: mild and accessible. Hard chambers work up to 2.0 ATA and are built for intensive and professional use. You can buy or lease both; soft chambers can also be rented. In our showroom in Goes you can feel the difference yourself, and we are happy to think along with you.
What do you notice of the pressure?
While the pressure builds you feel it on your ears, as in a plane or when diving. Swallowing or yawning clears them. That is why the pressure is built up calmly, and released calmly at the end.
Common pressures
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| Pressure | Absolute | Gauge | Comparable depth |
|---|---|---|---|
| 1.3 ATA | 132 kPa · 1.32 bar · 19.1 psi | 0.3 bar · 4.4 psi | 3 m |
| 1.4 ATA | 142 kPa · 1.42 bar · 20.6 psi | 0.41 bar · 5.9 psi | 4 m |
| 1.5 ATA | 152 kPa · 1.52 bar · 22 psi | 0.51 bar · 7.3 psi | 5 m |
| 2 ATA | 203 kPa · 2.03 bar · 29.4 psi | 1.01 bar · 14.7 psi | 10 m |
| 3 ATA | 304 kPa · 3.04 bar · 44.1 psi | 2.03 bar · 29.4 psi | 20 m |
Frequently asked questions about pressure
Is 1 ATA the same as 1 bar?
Almost. 1 ATA is 101.325 kPa and 1 bar is 100 kPa, so 1 ATA is 1.013 bar absolute. Check whether a figure is absolute or gauge: 1.0 ATA is 0 bar gauge.
What does 1.5 ATA mean?
The total pressure is one and a half times the air pressure at sea level: 152 kPa or 1.52 bar absolute, or 0.51 bar or 7.3 psi gauge. That is comparable to about five metres under water.
How many PSI is 2.0 ATA?
2.0 ATA is 29.4 psi absolute (psia) and 14.7 psi gauge (psig). US spec sheets often state the gauge pressure.
What is the difference between absolute and gauge pressure?
Absolute pressure is the total pressure, including normal air pressure. Gauge pressure is only the part above it. Absolute = 1 atm + gauge.
At what pressure do OxyBoost chambers work?
Our soft chambers work at 1.3 to 1.5 ATA, our hard chambers at 1.5 or 2.0 ATA. The medical chambers OxyBoost supplies go up to 3.0 ATA (single-person) and 6.0 ATA (multi-person).
Where would you like to go next?
That is the best way to choose.
Our showroom in Goes has many of our systems set up and running. Take a training, feel the difference between the technologies and work through with us what it would mean at your location.