Page 3 - Demo

page3Historic Gas Times%u2022 Issue 112 %u2022 September 2022 %u2022communicating holes were made. Through these a diver, using normal deep sea equipment, was sent to guide the pump suction. But though the method may intrigue, the outcome proved disappointing; for time had made the deposit so hard that the sludge pump was only partly effective.%u2018Right%u2019, then said the engineers, %u2018we%u2019ll use a fire hose. That%u2019ll stir up something%u2019, Due to the back pressure created, it would have stirred up the diver as much as the deposit had he attempted to use a hose in simple fashion under water, so a number of small holes were drilled at the rear of the nozzle, The resultant jets creating a force in the opposite direction, counteracted the thrust of the main jet and rendered the hose manageable. The jets, playing backwards, made the diver wet (as he jokingly put it) but the operation went according to plan. The deposit was found to have been over 2 feet deep in places; over 100 tons were removed in 22 working days; and during the whole period the holder was kept fully inflated under air pressure.While the holder was out of action, opportunity was also taken to give it an internal overhaul, with all the lifts down, a hole was cut in the holder crown, through which two sectional rafts were lowered and assembled floating on the surface of the water. Next, an air-lock (or pressure equalising chamber with air tight doors) was fitted over the hole in the crown, an essential item, as will be readily appreciated, to enable people to get in and out of a holder held up by air pressure; also a hand windlass %u2014 the motive power for the bosun%u2019s chair, by means of which descents and ascents are made.A bosun%u2019s chair is no more elaborate than a children%u2019s swing, to which it might be likened and as a mode of transport, needs treating with respect, for it swings, and moreover unless the passenger keeps a hold on the guide ropes provided, it will also spin.Descents are made in the chair to an accompaniment of flashlamp signals, for any shouts made inside a gasholder reverberate to such an extent as to be unintelligible to the men working the windlass. The long drop (in this case of about 120 feet) in a landing on one of the rafts positioned immediately beneath the hole in the crown, the final stage of the %u2018journey to work%u2019 being through the medium of the second raft which is paddled to any required point. By such means a holder is examined and necessary internal repairs carried out.It is common knowledge what a %u2018gasometer%u2019 looks like %u2013 from the outside. But few, even our own readers, have ever gazed at one from within, or, indeed, have ever thought of the possibilities of doing so. Therefore, because the subject is unusual, we present it without apology, although as a technical presentation it may dismay engineers. On the other hand, had the article been written solely from an engineering angle, it might have dismayed others far more.Those accustomed to working on holders tend to regard their work with a measure of stoicism. But for those who climb up the outside of a large holder for the first time, and then swing on a bosun%u2019s chair into the dim, cathedral-like interior, the experience has its thrills. Perhaps some of the thrills will have been conveyed, at least in part, to the reader, although seeing an aeroplane stunt, from the ground, is never quite the same as seeing a plane stunt, from the plane. Ask our photographer.Based on an article published in the SEGAS JOURNAL June 1953A sketch of descending into the gasholder on the bosun%u2019s chair.At the base of the gasholder descending on the bosun%u2019s chair to the raft, the framing of the gasholder is visible, as are the inlet and outlet mains.