| 摘要 |
A liquid sampler including a force main sampling chamber, a seal leg having an end portion immersed in liquid in said sampling chamber, a dam in the sampling chamber for maintaining the liquid at a predetermined minimum elevation therein, a draw tube in communication with the seal leg, a pump for supplying either compressed air or vacuum to the draw tube, first control means for causing the pump to supply vacuum to the draw tube only when a sample is to be taken, a side arm in the draw tube for receiving liquid, second control means including non-contact liquid-level sensing means in the draw tube for causing the pump to supply pressure rather than vacuum after the liquid reaches a predetermined level in the draw tube, and circuit means for terminating operation of the sampling cycle in the event a sample is not taken within a predetermined time period after the sampling cycle is initiated.
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