| 摘要 |
A hydrant has a standpipe (2) which is connected to the water main by the body of the shut-off valve (5). A housing (3) fitted to the upper end of the standpipe has two outlets (28, 28'), each of which is fitted with a valve (23, 22). The hydrant is brought into use by swinging the cover (21) to one side and rotating the actuating spindle (17) to open the shut-off valve (5). One or both outlet caps (30) can be removed and water is then made available by actuating one or both of the valves (22, 23). The pressure of water in the standpipe presses the actuating rod (17) upwards and prevents the replacement of the cover (21). The shut-off valve (5) must be closed to allow the actuating rod to be retracted. This ensures that the standpipe is drained through the non-return valve (33) before the cover is replaced. USE/ADVANTAGE - Draining the stand-pipe prevents the hydrant from being frozen.
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