Wednesday, 27 October 2010

Pressure drop

This post on Paul Bailey’s blog refers to the phenomenon of “top pressure”, which was widespread in the 1970s, and was described and decried at length in CAMRA publications. What this involved was delivering real ale to pubs in casks, but then connecting a cylinder of CO2 to it, and using the gas pressure to force the beer to an illuminated keg-type font on the bar.

It must have largely been a Southern phenomenon, as I don’t recall ever knowingly coming across it in the North, where a lot of the beer was real, and a lot of what wasn’t real was “tank” (which maybe merits a post of its own). In fact the only occasion when I have drunk what I believed to be top-pressure beer was in a Whitbread pub in Alton, Hampshire in about 1981. By that time the practice was in steep decline, as real ale, and the handpumps that symbolised it, were once again perceived as attractive.

The system also had a unique drawback of its own, in that not only did the gas pressure make the beer fizzy and prevent it maturing in the cask, but it also tended to disturb the sediment, so you would end up with a pint of slightly hazy pseudo-keg. Thirty years or more on, it’s hard to see why it was done, as it combined the worst of both worlds, lacking both the freshness and authenticity of cask and the consistency of genuine keg.

But, back in those days, fizzy beer that came from illuminated boxes on the bar was seen as the future, and brewers who lacked the funds to invest in kegs, kegging lines and pasteurisation facilities climbed on the bandwagon by sending out cask beer and making it masquerade as keg. How times change.


  1. I think you're correct Curmudgeon, about "top pressure" being a largely southern phenomenon. I certainly don't recall seeing (or tasting) any evidence of it when I moved up to Greater Manchester, back in late 1973. On the other hand I hadn't encountered tank beer prior to this, and was certainly bemused by seeing beer tankers delivering to certain pubs. (Greenall Whitley seemed to favour tank beer, especially in their larger pubs).

    The majority of pubs where I lived in East Kent, belonged to either Courage or Whitbread, and both companies favoured "top pressure" systems for dispensing their beer.

    I think it was largely used to ensure that casks lasted longer, but on the downside it certainly made the beer fizzy. The illuminated boxes on the bar that you mention, were also seen as the way forward at the time.

    Sheps, who were our only local brewery back then, were still using handpumps in the majority of their pubs. I don't know about companies further afield, but if the comment in CAMRA's first (1974) Good Beer Guide is to be believed, Harvey's must have been using "top pressure" ("Difficult to find real ale.")

  2. I assume the "tank" beer is essentially the same as "tankove" systems used in the Czech Republic? If so they are a step up from kegged lager in my experience.

  3. Is this the same as blanket pressure, which wasn't intended to push beer down pipes, just to protect it from the air? It was supposed to be unnoticeable, but you could detect it, particularly later in the cask. I know a pub here in Southport that did that in the 1970s.

  4. Top pressure was generally regarded as worse than blanket pressure as the CO2 was actually used to push the beer to the bar, and thus more of it ended up dissolved.

  5. this was suggested by Whitbread in a free house I ran in 1986 as a solution to traditional beer engine's not being able to pull beer from our cellar. (it was nearly 150ft from the cask to tap).

    I tried top pressure and rejected it as the side effects detailed above were evident.

    they replaced them (after much cajoling) with a modified impeller pump which delivered it to a "staging" tank below the bar for the hand pulls to pull from.

    meant extra cleaning etc but worked really well


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