Fluke RUSKA 7252, User Manual

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Maintenance
Calibration
6
6-3
Vacuum Pumps
Periodic checks of the user’s vacuum pumps for oil levels. It is very highly recommended
that a power-down vacuum venting valve is installed onto the vacuum pumps to ensure
minimal chances of oil contamination from the vacuum sources. These are normally open
solenoid valves that are powered through the vacuum pump power switch. When the
vacuum pump is turned on, the solenoid valve is energized and closes allowing the pump
to operate normally. When the pump is turned off, power is removed from the solenoid
and the vacuum is vented to atmosphere. Periodic changing of vacuum pump oil should
also be done as recommended by the vacuum pump manufacturer.
Processor Battery
The processor board uses a lithium battery to maintain time and date information. This
battery has a varying life. If the instrument is left on 24 hours a day, it may last 5 to 10
years. If the instrument is stored, it may only last one year. Annual replacement is
recommended. To replace the battery:
1.
Turn off power and remove the instrument cover (see above, Chapter 6, Removing
the Calibrator’s Cover).
2. Remove the processor card by removing the screw and the bracket that locks the
display cable in place and gently rock the card upward.
3. Holding the processor card, remove the battery (the round silver object), by carefully
pulling on the battery.
4. Plug in a new battery (part number 4-725).
5. Reinstall the processor card, the bracket that locks the display cable in place, and the
screw. Replace the instrument cover.
6. The time and date may have to be re-entered. See Chapter 4, Menu
⎢
Setup — Remote.
Calibration
To keep the Calibrator operating within its specified precision, the calibration procedure
described below should be performed once every year. If a higher level of overall
performance is desired, the user can calibrate more frequently.
Note
The calibration procedure automatically generates coefficients that are
stored in memory on the Calibrator. If these constants are “lost” for any
reason, the calibration procedure must be performed, regardless of the last
calibration date. If the calibration coefficients have been recorded, they
may be restored to the Calibrator at any time by “editing the coefficients”
(Chapter 6, RPT Calibration – Simulated Absolutes)).
Calibration Instructions
To calibrate the RUSKA 7252, the user connects a calibration standard such as the
RUSKA Instrument Model 2465 (or 2470 for high pressure ranges) Gas Piston Gauge to
the Calibrator’s test port, then follows the multi-step calibration procedure on the
Calibrator’s display. The standard Calibrator requires a positive pressure calibration.
A vacuum (negative gauge) option is available and requires special calibration per
Chapter 6, Vacuum (Negative Gauge) Calibrations. No disassembly is required and there
are no potentiometers to tune.
Note
The uncertainty of the final calibration must include the uncertainty of the
pressure standard being used.