Hach 3654 Portable H2/N2 Analyzer manual Taking Measurements, Select Gas Measurement Phase

3654 Portable H2/N2 Analyzer - Operating Instructions 19 of 66

2.2 Taking Measurements

To start the analyzer, press the POWER switch (located bottom left of the keyboard). When you turn power on, the instrument displays the software version number briefly, and then starts a series of start-up tests. This process should take only a few minutes, during which time a [tSt] message is displayed on the LCD. Once the tests are completed, a clearing message [---]is displayed for a further sixty seconds before the instrument switches automatically to measurement mode.

Note:

The start-up tests will be repeated until successful, or for a maximum of 15 minutes. If the tests are still unsuccessful after 15 minutes, a [Err] message will be displayed and the instrument locked. Turn the instrument off and retry the start-up procedures, but if the problem persists, please contact your local Hach Ultra service representative for assistance.

Measurement updates are displayed every 20 seconds, and it is normal for the right- most digits to vary in reaction to slight variations in gas content. For accurate measurements, the sensor's membrane must be at the same temperature as the sample to be analyzed. If this not the case, allow some sample to pass through the flow chamber for about 3 minutes before taking any measurements.

Minimum sample flow rates, measurement ranges and response times for the various membranes are given in the tables in “Sensor Specifications” on page 56.

The LCD includes a right-side marker to distinguish between gas concentration measurements and temperature. This marker also indicates the measurement display units (k/kg, V/V, etc. depending on the instrument configuration).

To switch between gas measurement and temperature measurement, press the Up/ Down Arrow buttons. To illuminate the LCD for approximately three minutes, press the Backlight button.

2.2.1 Select Gas Measurement Phase

Ensure the gas measurement phase is correct for this measurement. For details on viewing the current setting, refer to “Reviewing Instrument Configuration” on page 29. For details on changing this setting, refer to “Configuring the Instrument” on page 29.

2.2.2 Measurement Mode

You can set the measurement mode to normal or maximum. For details on how to do this refer to “Measurement Mode” on page 33.

Maximum mode facilitates making measurements in bottles and cans. To search for a maximum measurement value, press the MEAS button.

•The LCD first shows the message [run] for a few seconds, before displaying measurement values.

•After a 60 second measurement cycle, the instrument searches for two consecutive gas measurements with less than 2% difference. When this condition occurs, the displayed value freezes on the LCD (indicated by a blinking display), allowing you to note down or store the data.

The display remains frozen until you press the MEAS button to make a new measurement, or you select normal measurement mode (as described in “Measurement Mode” on page 33).

Operator Manual ORBISPHERE