▁to ▁the ▁number ▁and ▁orientation ▁of ▁the ▁components ▁in ▁the ▁end - face ▁mechanical ▁se al ▁assembly . ▁ ▁For ▁example , ▁spr ings ▁may ▁be ▁rot ating ▁or ▁station ary . ▁ ▁Single ▁or ▁multiple ▁pairs ▁of ▁se aling ▁faces ▁may ▁be ▁used . ▁ ▁For ▁multiple ▁se als , ▁the ▁individual ▁pairs ▁of ▁se aling ▁faces ▁may ▁be ▁similarly ▁orient ed ▁or ▁opposed . ▁ ▁Cont ain ment ▁devices ▁such ▁as ▁bush ings ▁may ▁or ▁may ▁not ▁be ▁used ▁as ▁part ▁of ▁the ▁configuration . ▁ ▁Component ▁vs ▁cart ridge ▁ ▁The ▁basic ▁components ▁of ▁an ▁end - face ▁mechanical ▁se al ▁may ▁be ▁installed ▁directly ▁onto ▁the ▁sh aft ▁but ▁a ▁popular ▁approach ▁is ▁to ▁pre - ass emble ▁the ▁components ▁into ▁some ▁sort ▁of ▁package ▁for ▁ease ▁of ▁installation . ▁ ▁When ▁the ▁components ▁are ▁pre - ass emble d ▁onto ▁a ▁sle e ve ▁and ▁g land ▁plate , ▁the ▁complete ▁assembly ▁is ▁called ▁a ▁cart ridge ▁se al . ▁ ▁This ▁complete ▁assembly ▁can ▁be ▁easily ▁sl id ▁onto ▁the ▁sh aft ▁and ▁bol ted ▁in ▁place ▁thus ▁reducing ▁the ▁potential ▁for ▁installation ▁errors . ▁ ▁Some ▁cart ridge ▁se als ▁use ▁regular ▁component ▁se al ▁parts ▁whereas ▁other ▁cart ridge ▁se als ▁might ▁use ▁specific ▁purpose ▁parts . ▁ ▁API ▁ 6 8 2 ▁spec ifies ▁that ▁only ▁cart ridge ▁se als ▁are ▁acceptable ▁to ▁the ▁standard . ▁ ▁Rot ating ▁vs ▁station ary ▁spr ings ▁▁ ▁Either ▁the ▁se al ▁ring ▁or ▁the ▁m ating