"AIR LOCK" IN WATER PIPES.

Auckland Star, Volume LI, Issue 7, 8 January 1920, Page 8

"AIR LOCK" IN WATER PIPES.

SHORT PRESSURE AT TIMBER FIRE. A report from the city waterworks engineer, Mr. J. Carlaw, explains the reason for the failure of the water pressure at the time of the fire at Cashmore Bros*, sawmill on Tuesday. He states that West End Road, on which the mill is srhrated, ie eapplied through a 4in main, -which finishes with a dead end et tie waterside at Cox's Creek, and he is of opinion that at the moment of making- the large dra-w off for the fire the pressure in this main was so reduced as to cause the ball valves to drop, and allow the entrance of air, causing an air Jocfc at the highest part of the main, where rfc is really a, ayphon. The airJock would not allow the passage of "water unta the lock was removed. Mr. Carlaw added that on discovering this •lock he turned on the Mt. Eden pressure to Grey Lynn, so that there was nearly 2001b to the inch on tiat Eide of the creek. Ifc was impossible to force -■ out the lock onring to the dead end, but under ordinary circumstances the preseure at the scene of thte fire ehoujd have been 13(ffl> to the inch. It was one of those unfortunate occurrences it was impossible to foresee or prevent, but only once before had he experienced it - many yara ago in Seafield View Boat