Cylinders

What it's for

Reference tables of cylinders, plus free-gas capacity and tank factor helpers. Look a cylinder up by id in CYLINDERS_BY_ID, or iterate DIVE_CYLINDERS, STORAGE_CYLINDERS and INDUSTRIAL_CYLINDERS.

Formulas

Ideal free gas, in surface litres:

$$V_{free}=V_w{P}_{gauge}$$

Real free gas, using the ideal-equivalent pressure from Real gas:

$$V_{free}=V_w(P_{ideal}(P_{gauge}+1.01325)-1.01325)$$

Tank factor, cubic feet of free gas per 100 psi:

$$TF=\frac{100V_w}{28.3168466\times 14.5037738}$$

• $V_w$: cylinder water volume, L. $P_{gauge}$: gauge pressure, bar.
• $P_{ideal}$: ideal-equivalent absolute pressure, bar.
• $V_{free}$: free gas, surface litres. $TF$: cu ft per 100 psi.

Nominal vs real cubic feet

A cylinder's "cubic feet" rating (80 for an AL80) is a nominal free-gas figure, and it does not match what the cylinder holds at its rated pressure.

An AL80 has a water volume of 11.1 L and a service pressure of 3000 psi (206.8 bar). The ideal formula gives $11.1\times 206.84=2296$ L, or about 81.1 cu ft. With real-gas behaviour at that pressure the cylinder holds about 77.9 cu ft, which is why an AL80 is closer to 77 cu ft than 80. Pass useRealGas: true to freeGas to get the real figure.

Tables

Water volume is the internal volume. Rated pressure is the service pressure in bar gauge, converted from psi where the source uses psi.

Dive cylinders (DIVE_CYLINDERS)

ID	Name	Water volume (L)	Rated pressure (bar)	Material
AL80	AL80 (S80)	11.1	206.8	aluminum
AL63	AL63 (S63)	9	206.8	aluminum
AL40	AL40	5.7	206.8	aluminum
AL30	AL30 (pony)	4.3	206.8	aluminum
AL19	AL19 (pony)	2.9	206.8	aluminum
AL100	AL100	12.9	227.5	aluminum
HP15	HP15	2	237.3	steel
HP23	HP23	3	237.3	steel
HP71	HP71	9	237.3	steel
HP80	HP80	10.2	237.3	steel
HP100	HP100 (Faber)	12.9	237.3	steel
HP117	HP117 (Faber)	15	237.3	steel
HP120	HP120 (Faber)	15.3	237.3	steel
HP133	HP133 (Faber)	17	237.3	steel
HP149	HP149 (Faber)	19	237.3	steel
HP119	HP119 (Worthington)	15	237.3	steel
HP130	HP130 (Worthington)	16.3	237.3	steel
LP27	LP27	4	182.0	steel
LP50	LP50	7.8	182.0	steel
LP85	LP85	13	182.0	steel
LP95	LP95	15	182.0	steel
LP108	LP108	17	182.0	steel
LP120	LP120	19	182.0	steel
S12	Steel 12 L	12	232.0	steel
S15	Steel 15 L	15	232.0	steel
S7	Steel 7 L (stage)	7	232.0	steel
S3	Steel 3 L (pony)	3	232.0	steel

Storage cylinders (STORAGE_CYLINDERS)

ID	Name	Water volume (L)	Rated pressure (bar)	Material
UN45-310	UN 45 L (310 bar)	45	310.0	steel
UN50-300	UN 50 L (300 bar)	50	300.0	steel
UN50-232	UN 50 L (232 bar)	50	232.0	steel

Industrial cylinders (INDUSTRIAL_CYLINDERS)

ID	Name	Water volume (L)	Rated pressure (bar)	Material
T	T cylinder (Airgas 300)	49	165.0	steel
K	K cylinder (Airgas 200)	43.8	156.0	steel
L50-200	Linde/Messer 50 L (200 bar)	50	200.0	steel
L50-300	Linde/Messer 50 L (300 bar)	50	300.0	steel

Assumptions and limits

• Free gas is above 0 gauge, so it is volume × pressure in the ideal case, not absolute.
• Tank factor is unrounded and ideal.
• Real-gas free gas defaults to AIR. Pass gas for other mixes.
• The real-gas model is valid to 500 bar absolute.

Sources

Each row carries its own source. By group:

• Aluminium AL series: Luxfer scuba cylinder specifications (3000 psi service; AL100 at 3300 psi).
• HP series: Faber F-x Series HP exempt spec sheet (3442 psi), and Worthington/PST X-series spec sheet (3442 psi) for HP119 and HP130.
• LP series: Faber DOT 3AA LP spec sheet (2640 psi, +10%).
• S series: EN 1964 steel, water volume by definition (232 bar).
• Storage: UN/EN storage cylinders, water volume by definition.
• Industrial T and K: Airgas cylinder dimensions (ap003.pdf) and size chart (ap004.pdf). L50 series: Linde / Messer Reine Gase 2021.

Examples

import { CYLINDERS_BY_ID, freeGas, tankFactor } from 'dive-math/cylinders'
CYLINDERS_BY_ID.AL80.volumeL // => 11.1
freeGas({ volumeL: 10, pressureBar: 200, useRealGas: true }) // => 1928.6
tankFactor(11.1) // => 2.70

API

See the cylinders API reference.