Maximum Operating Depth (MOD)

The MOD is the maximum depth to dive with a gas mixture containing a specific oxygen content. The MOD is a function of oxygen exposure, the breathing of a specific partial pressure of oxygen (PO2) for a specific amount of time.

The maximum PO2 for sport diving is widely considered to be 1.6 ATA, limiting dives to 45 minutes. Higher than 1.6 ATA, the risk of central nervous system oxygen toxicity increases dramatically. A lower PO2 allows a longer dive with a lower oxygen exposure. Technical divers and sport divers with longer bottom times usually limit their PO2 to 1.3 or 1.4 ATA.

Maximum Operating Depth (fsw) *MOD fsw = ( ( Desired PO2 ATA / Fraction of Oxygen in Gas ) 33 fsw ) - 33 fsw**
Oxygen	Atmospheres Absolute (ATA)				Oxygen	Atmospheres Absolute (ATA)
Oxygen	1.6	1.5	1.4	1.3	Oxygen	1.6	1.5	1.4	1.3
10%	495	462	429	396	33%	127	117	107	97
11%	447	417	387	357	34%	122	113	103	93
12%	407	380	352	325	35%	118	108	99	90
13%	373	348	322	297	36%	114	105	95	86
14%	344	321	297	273	37%	110	101	92	83
15%	319	297	275	253	38%	106	97	89	80
16%	297	276	256	235	39%	102	94	85	77
17%	278	258	239	219	40%	99	91	83	74
18%	260	242	224	205	41%	96	88	80	72
19%	245	228	210	193	42%	93	85	77	69
20%	231	215	198	182	......	......	......	......	......
21%	218	203	187	171	50%	73	66	59	53
22%	207	192	177	162	51%	71	64	58	51
23%	197	182	168	154	52%	69	62	56	50
24%	187	173	160	146	......	......	......	......	......
25%	178	165	152	139	80%	33	29	25	21
26%	170	157	145	132	81%	32	28	24	20
27%	163	150	138	126	82%	31	27	23	19
28%	156	144	132	120	......	......	......	......	......
29%	149	138	126	115	100%	20	17	13	10
30%	143	132	121	110
31%	137	127	116	105
32%	132	122	111	101

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Maximum Operating Depth (MOD)

Maximum Operating Depth (fsw)