▁some , ▁particularly ▁in ▁the ▁UK , ▁since ▁the ▁ 1 9 6 0 s ▁when ▁paste ur ised ▁dra ug ht ▁be ers ▁started ▁replacing ▁traditional ▁c ask ▁be ers . ▁ ▁K eg ▁be er ▁was ▁replacing ▁traditional ▁c ask ▁ale ▁in ▁all ▁parts ▁of ▁the ▁UK , ▁primarily ▁because ▁it ▁requires ▁less ▁care ▁to ▁handle . ▁Since ▁ 1 9 7 1 , ▁C AM RA ▁has ▁conducted ▁a ▁consumer ▁campaign ▁on ▁beh alf ▁of ▁those ▁who ▁prefer ▁traditional ▁c ask ▁be er . ▁C AM RA ▁has ▁lo bb ied ▁the ▁British ▁Parliament ▁to ▁ensure ▁support ▁for ▁c ask ▁ale ▁and ▁micro bre wer ies ▁have ▁spr ung ▁up ▁to ▁serve ▁those ▁consum ers ▁who ▁prefer ▁traditional ▁c ask ▁be er . ▁ ▁Press ur ised ▁CO 2 ▁in ▁the ▁k eg ' s ▁head space ▁maintain s ▁carbon ation ▁in ▁the ▁be er . ▁The ▁CO 2 ▁pressure ▁var ies ▁depending ▁on ▁the ▁amount ▁of ▁CO 2 ▁already ▁in ▁the ▁be er ▁and ▁the ▁k eg ▁storage ▁temperature . ▁Occ asion ally ▁the ▁CO 2 ▁gas ▁is ▁bl ended ▁with ▁nit ro gen ▁gas . ▁CO 2 ▁/ ▁nit ro gen ▁bl ends ▁are ▁used ▁to ▁allow ▁a ▁higher ▁operating ▁pressure ▁in ▁complex ▁disp ens ing ▁systems . ▁ ▁N it ro gen ▁is ▁used ▁under ▁high ▁pressure ▁when ▁disp ens ing ▁dry ▁st outs ▁( such ▁as ▁Gu in ness ) ▁and ▁other ▁cre amy ▁be ers ▁because ▁it ▁disp laces ▁CO 2 ▁to ▁( art ific