within sections 71 disposed therebelow in sections 72 is a fitment o ring 76 disposed within each of inserts 74 and extending therebelow and abutting o rings 76 are split bushings shown generally at 77 the split bushings 77 further comprise radially projecting metal blades 78 shown in phantom the function of which will be more appropriately described in the context of the following paragraph referring to fitments 36 and 38 which are best illustrated in fig5 each comprises a vertically extending minor portion 80 which is slidably inserted into their respective ports 35 and 37 thereby extending through split bushings 77 inserts 74 and fitment o rings 76 thus inserted through o rings 76 minor portions 80 are sealingly engaged in fluid communication with element 32 via through bores 75 within ports 35 and 37 once inserted into ports 35 and 37 fitments 36 and 38 are prevented from being inadvertently pulled out of ports 35 and 37 by the action of split bushings 77 compressing when abutted against inwardly tapered insert 74 thus forcing inwardly radially projecting blades 78 against minor portions 80 thereby effectively locking minor portions 80 within ports 35 and 37 in order to remove fitments 36 and 38 from ports 35 and 37 a radially projecting flange 81 molded onto split bushings 77 must be manually or otherwise held stationary against vessel head 16 thereby preventing split bushing 77 from abutting inwardly tapered insert 74 so that inwardly radially projecting blades 78 will not lock onto minor portions 80 and so that fitments 36 and 38 may be freely slidingly extracted from their.