Page 2 - Demo

Millions of folk go to work by bus, train or bike, or other means and a few - a very tiny minority go by bosun%u2019s chair. To misquote, there are many who owe much to these few. For a gasholder is used not only to store gas but also to supply pressure to push the gas through the mains to consumers. The work of the few results in a holder being kept in action when after long usage, it shows signs of becoming unserviceable.Big things, gasholders. Unlike a Meccano set, or even large and heavy pieces of machinery, they can%u2019t be taken apart, or examined and repaired on a table or workshop bench, any attention they need has to be given %u2018on the site%u2019. Sometimes, though usually at intervals of many years, it is necessary to get right inside them. Such a necessity arose at Wandsworth Gasworks recently, and as in more ways than one the procedure could be likened to a series of %u2018what would you have done?%u2019 problems favoured by some American magazines, an outline of the happenings may interest readers, even those who are little concerned with engineering.There are more ways than one of getting into a gasholder. You can be let down inside on a bosun%u2019s chair, through a hole cut in the crown (or roof); or get in or out, as the gas does through a main (practical exposition of the verb %u2018to wriggle%u2019). But whatever the method chosen, if the holder is of any size at all, once inside you will be confronted with enough water to fill a dozen swimming pools. Everything is eerie, vast and dark, for all natural light is excluded, and the insignificance of artificial lights in such a huge area makes the water look black and sinister, perhaps even more so if you happen to be unable to swim and know that it is 40 feet deep.The conventional gasholder can be likened to an immense inverted cup rising and falling in this tank of water (which of course serves to seal the gas), the %u2018cup%u2019 being guided in its movements by rollers, both internal and external. One cause of trouble with holders and this applied to No.5 Holder at Wandsworth %u2013 is that over a long period of years, wind and rain sweep dust into the tank, which accumulates ultimately in insufficient quantity to damage the lifts of the holder when they descend upon it, by causing the side sheets to buckle. When this threatens it is usual to put the holder out of commission, blow out the residual town gas with inert gas, pump the tank empty and dig out the deposit.It was, however, thought inadvisable to pump out the tank of No.5 holder, as the pressure of water in the surrounding ground might have caused damage to the tank and it was therefore decided to remove the deposit by pumping. To this end two pits each 7 feet deep, were sunk just outside, the tank, into whichHistoric Gas Times%u2022 Issue 112 %u2022 September 2022 %u2022pagepage22The first man into the gasholder always carried the box, seen in the centre of the picture, which contained mice, they would be an early indicator of foul air within the gasholder. The people are about to enter the air box which is attached to the top of the gasholder crown and sealed, when the door is closed the box was pressurised to the same pressure as the gasholder, which had been purged of towns gas.MEN OF THE DARK WATERSONE WENT DOWN. OTHERS CAME UP TO COME DOWN. AND IF THIS SEEMS A RIDDLE, THE ANSWER IS IN THE ARTICLE.