HACH LANGE ORBISPHERE 3654, Руководство пользователя, Страница: 43 / 58

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Section 8 Maintenance and Troubleshooting
8.1 Power supply
It is important to maintain power to the instrument at all times, (either batteries or an external
power supply) to ensure the sensor is continually purged and so prevent damage to the TC
sensor chip.
If the 3654 instrument is operating on battery power (two standard C-type cells), and the battery
power should drop, a
[LO BAT]
warning message is displayed in the instrument LCD's top left
corner.
To install the batteries, unscrew the battery cap (on the right side of the instrument) with the tool
provided in the recharge kit, or with a coin or flat bladed screwdriver. Place the cells lengthwise
into the battery compartment (positive end first), and then replace the cap. Refer to the diagram
on the back of the instrument.
Rechargeable nickel-cadmium batteries may be used. Expect about 15 hours of autonomy in
continuous operational use, or 3 weeks in standby (with purge gas supplied). Alkaline batteries
provide the longest continuous use though mercury-free batteries are available that present less
of a disposal problem.
Make sure that a fully charged (or fresh) set of batteries is installed before switching on the
instrument.
8.2 Sensor maintenance
8.2.1 Maintenance schedule
Sensor maintenance includes membrane replacement and external cleaning to restore the
original sensor sensitivity. This means low running costs and down time reduced to a minimum.
The membrane needs to be replaced once or twice a year depending on application conditions.
This can be tailored accordingly.
Note:
If you are not familiar with ORBISPHERE sensor servicing, your Hach Lange representative will be
glad to assist you.
8.2.2 Mounting dual membranes
In order to prevent unwanted stretching of the membrane on a hydrogen sensor it is
recommended to simultaneously mount a support membrane beneath the primary membrane.
The primary membrane, or top membrane, determines the rate at which the H
2
gas enters the
measurement chamber of the sensor. The secondary membrane, or support membrane on the
bottom, is extremely permeable and is installed to stabilize the position of the primary
membrane.
Two primary membrane types are used for H
2
measurement depending on the type of
application:
• 29561A
- used for waste gas, off gas and dH
2
in a boiling water reactor
• 2952A
- used for dH
2
in reactor cooling systems of a pressurized water reactor.
The support or secondary membrane for all H
2
measurement applications is the
29562A
.
As two membranes will be mounted together, the mounting ring used must be part number
29229
which is designed for a thickness of 50 microns or more. Mounting ring part number
29228 is designed for a single membrane and should not be used for mounting dual
membranes.