), ▁equivalent ▁to ▁a ▁partial ▁pressure ▁of ▁ 1 . 9 ▁bar , ▁and ▁chamber ▁o xygen ▁decom pression ▁at ▁ 5 0   f sw ▁( 1 5   ms w ), ▁equivalent ▁to ▁ 2 . 5 ▁bar . ▁ ▁Rep et itive ▁div es ▁ ▁Any ▁d ive ▁which ▁is ▁started ▁while ▁the ▁t issues ▁retain ▁resid ual ▁in ert ▁gas ▁in ▁excess ▁of ▁the ▁surface ▁equilibrium ▁condition ▁is ▁considered ▁a ▁repet itive ▁d ive . ▁This ▁means ▁that ▁the ▁decom pression ▁required ▁for ▁the ▁d ive ▁is ▁influenced ▁by ▁the ▁diver ' s ▁decom pression ▁history . ▁Allow ance ▁must ▁be ▁made ▁for ▁in ert ▁gas ▁pre loading ▁of ▁the ▁t issues ▁which ▁will ▁result ▁in ▁them ▁containing ▁more ▁dissol ved ▁gas ▁than ▁would ▁have ▁been ▁the ▁case ▁if ▁the ▁diver ▁had ▁fully ▁equ il ibr ated ▁before ▁the ▁d ive . ▁The ▁diver ▁will ▁need ▁to ▁decom press ▁longer ▁to ▁eliminate ▁this ▁increased ▁gas ▁loading . ▁ ▁Sur face ▁interval ▁ ▁The ▁surface ▁interval ▁( SI ) ▁or ▁surface ▁interval ▁time ▁( S IT ) ▁is ▁the ▁time ▁spent ▁by ▁a ▁diver ▁at ▁surface ▁pressure ▁after ▁a ▁d ive ▁during ▁which ▁in ert ▁gas ▁which ▁was ▁still ▁present ▁at ▁the ▁end ▁of ▁the ▁d ive ▁is ▁further ▁elimin ated ▁from ▁the ▁t issues . ▁This ▁continues ▁until ▁the ▁t issues ▁are ▁at ▁equilibrium ▁with ▁the ▁surface ▁press ures . ▁This ▁may ▁take ▁several ▁hours . ▁In ▁the ▁case ▁of ▁the ▁US ▁Navy ▁ 1 9 5 6 ▁Air