Figure C–3.1. Vent  Assembly Model  53029B–20 (1) (2) (3) (4) (5) (6) (7) (8) ILLUSTRATION DESCRIPTION QTY (a) (b) NAT  IONAL INC FIG ITEM SM’R STOCK PART IN NO NO CODE NUMBER FSCM NUMBER USABLE  ON  CODE U/M UNIT C-3.1 Group 02 Vent Assembly C-3  .1 1 90696 EX  1333D-39 Cap,  Pressure  Relief,  2  In. 1 NPS C-3.1 2 90696 X-4797 Adapter,  Flanged,  Male, 1 Threaded C-3.1 3 90696 MS29513-250 O–Ring  Gasket 1 C-3  .1 4 96906 MS27078–11 Female Cap, 2“ NPSH With Pin 1 Lug  and  8“  Lng  Chain C-3.1 5 96906 SAEJ488 Washer_r Plain, 1/4” ID 8 C-3.1 6 96906 SAEJ105 Bolt, Hex-Hd, 1/4-20 UNC, 8 1.125  Long C–8 Change 1