Hanna Instruments BL 7916 - Manual (Page 12)

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TROUBLESHOOTING GUIDE
ELECTRICAL
The pump does not operate when turned ON:
• Check the power supply and connections. Voltage should be
between 100 - 130 VAC for 115 V models and between 200
- 250VAC for 230 V models.
• See Installation section on page 11 or call your dealer or the
nearest Hanna Customer Service Center for technical assis-
tance.
OPERATING
Display does not indicate:
• Check that the pump is properly plugged in
• Check the fuse.
Display shows 1 on the far left hand side:
• Check electrode and/or electrode cable.
"No Dosage" LED is lit:
• Check the tank where the level controller is working or verify
the connection on the terminals (they must be short for the
pump to dose).
LIQUID
The pump operates but does not prime:
• Check for a clogged or loose filter on the suction valve
assembly. Retighten if necessary.
• Check to see if the pump is too high above the foot valve
assembly (HI 721005) in the feed tank. This vertical distance
should not exceed 1.5 meters (5 feet). Either lower the pump
or raise the feed tank.
• Check the pump head, suction and discharge valves for
blockage.
Pump flow rate is reduced:
• Check the pump head, discharge and injection valve assembly
for any clogging. Clean and reassemble.
• Check for any additional back pressure created since the last
flow rate was conducted.
• Check for any changes in the viscosity of the chemical being
used.
• Be sure that valves have been properly installed in the pump
head.
pH CALIBRATION
BL 7916 only:
• Ensure that the display selector switch is set to MEASURE and dip
the electrode tip in a neutral buffer solution (pH 7.01).
• Adjust the OFFSET trimmer to display 7.01 on the LCD.
• Rinse the electrode with clean water and
dip the electrode tip in pH 4.01 (acidic)
or pH 10.01 (alkaline) buffer solution.
• Adjust the slope trimmer to read 4.01 or 10.01 on the LCD.
The slope calibration with pH 4.01 buffer is suggested if the controller
will be used for acid measurements or pH values below 7, pH 10.01
is in turn recommended for alkaline measurements or pH values
above 7.