System Diagnostics - Hach Accu4 User Manual

Table 5 Status messages (continued)
Message Description
RLY (A, B, C, The relay is de-
D) INACTIVE energized.
Control relay: The
measured turbidity is
less than the setpoint.
Alarm relay: The
measured turbidity is
between the low and
high alarm setpoints.
Status relay: A selected
system diagnostic
condition has not been
identified.
RLY (A, B, C, The relay is de-
D) TIMEOUT energized.
Control relay: The
overfeed timer has
expired and must be
manually reset.
RLY (A, B, C, The relay is energized.
D) COUNTING
Control relay: The time
on the overfeed timer is
counting down, but has
not expired.

System diagnostics

1. From the Measure screen, push MENU and select TEST/MAINT.
2. Select a diagnostic option.
Option Description
CHECK Hold the analog outputs and relays at their present
CAL/HOLD values/on-off states for a maximum of 30 minutes.
26 English
Solution
—
Push MENU and select
TEST/MAINT>OVERFEED RESET
to reset the overfeed timer.
—
Option Description
OUTPUT 1 (or 2) Set the analog value that is present at the analog output
—0 (or 4) to 20 mA (default = 4.05 mA). Use this option
to confirm operation of the connected devices.
RELAY (A, B, C, Set the state of the relay—ENERGIZED or DE-
D) ENERGIZED. Use a continuity meter on the NO and NC
relay output terminals to confirm the relay status
selected.
SIM SENSOR Set the simulated turbidity measurement value—0.00 to
100.00 (default = 0.35 NTU). Use this option to confirm
that the analog outputs and relays respond correctly to
the simulated turbidity measurement.
3. Push ENTER or ESC to stop the test.
Remove bubbles from the flow cell
Two types of air or gas bubbles can be present in the sample:
• Bubbles that cannot be seen—made when air is absorbed into liquid.
This can occur naturally or be the result of human intervention such as
when ozone is injected into water to act as a disinfectant. Bubbles that
cannot be seen in the sample form and can be seen in the flow
chamber.
• Bubbles that can be seen—made when liquid and air are mixed. For
example, when water flows through a pipe that contains air or when
water falls.
Decrease the sensor outlet flow
Remove bubbles that cannot be seen in the sample but can be seen in
the flow chamber. To do this, decrease the sensor outlet flow to apply
pressure to the sample while it is being measured.
1. Keep the flow rate through the sensor within the specified limits.
Refer to Specifications on page 3.
2. Install a flow restrictor in the sensor outlet tube.
3. Adjust the flow restrictor until the flow is slightly decreased.
4. Close the 3-way valve to stop flow through the sensor.