Section 4

5.To exit the manual mode, press CLEAR ENTRY. This returns the sampler to the standby state.

While the sampler is in standby, a sample cycle can be initiated by pressing the TAKE SAMPLE key.

4.8 Measurements Triggered by Liquid Levels or Flow

The sampler can operate in any one of three control modes, using an external controlling device (i.e. Liquid Level Actuator, Cat. No. 943, or an external flow meter). In any of the three modes, the sampler remains in a standby state until liquid at the sample source reaches a predetermined level. This feature may be also used to access the setup of the storm water monitoring program, First Flush. The three modes are described below:

Mode 1

The instrument collects a sample within the first minute that the liquid rises to the predetermined level. After the first sample is taken, the sample interval automatically resets to the programmed interval.

If the liquid falls below the predetermined level, the sampler continues to collect samples at the programmed time or flow interval, until the program ends.

Mode 2

The instrument collects a sample within the first minute that liquid rises to the predetermined level. After the first sample is taken, the sample interval automatically resets to the programmed interval. The sample program ends if liquid falls below the predetermined level. If the liquid again rises to the predetermined level, a sample is taken within the first minute and the interval automatically resets to the programmed time or flow interval.

Mode 3

When the liquid rises to a predetermined level, a sample is not taken immediately. A sample is taken only when liquid is at or above the predetermined level and after the programmed sample interval has elapsed. The interval between samples counts down and resets even when the liquid level is below the predetermined (actuation) level. This mode is used to synchronize sample collection with a real-time clock when sampling in the time mode.

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Measurements Triggered by Liquid Levels or Flow

8544operations.fm

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Hach 900 manual Measurements Triggered by Liquid Levels or Flow, Mode