RUSKA 7050, 7050i & 7050LP
Users Manual
2-8
Case Reference Vacuum Sensor
The case reference vacuum sensor is a user installed option. The user needs this sensor to
zero an Absolute PPI. Please note that the uncertainty of the vacuum sensor used to zero
the PPI must be considered in the overall uncertainty analysis of the PPI.
Software
The PPI is a digital, software-based instrument.
Software Safety Controls
Oven Control
The oven temperature is controlled via a pulse-width modulated signal. The time the
heater is on can be varied from 0 to 100%. The pulse-width at startup is initialized to the
previous value, which was stored in the battery-backed CMOS RAM.
The oven control is a PID controller updated approximately every 7 seconds. The sensor
readings are accessed by pressing MENU | DISPLAY. With an exception of the 3000 psi
(20.7 MPa) version 7050, the high accuracy quartz sensor is housed in a temperature
controlled oven. There is a 3 hour warm-up time required prior to the PPI operating at its
optimum precision. The user can verify when the instrument is thermally stable by
viewing the MENU | DISPLAY screen and verifying that the temperature is at 50
o
C. In
addition to the temperature, this screen will show the duty cycle of the oven.
When operating the system in either a very cold or hot environment, if the oven in unable
to maintain the temperature of the internal oven, the PPI will generate an Oven Control
Failure error messages. The operator can review the temperature and duty cycle of the
oven by pressing the MENU | DISPLAY keys. The unit must have been warmed up for a
minimum of 3 hours prior to determining the condition of the oven temperature control.
The temperature of the sensor should be controlled to 50
o
C. The Duty Cycle indicates the
amount of time (in units of percentage) that the oven control is turned on in order to
maintain the oven at the proper set-point of 50
o
C. A unit that is operating properly, after
it has fully warmed up, should indicate a sensor temperature of 50
o
C and a duty cycle
between 10 to 90%.
If operating the instrument in a very cold environment and the oven duty cycle is at a
high percentage (>90%) you will need to turn the fan off. If you are operating in a warm
environment or when multiple systems are housed in consoles without adequate
ventilation, the system may become too hot and generate the Oven Control Failure error
message. If operating the instrument in a warm environment and the oven duty cycle is at
a low percentage (>10%) you will need to turn the fan on. See Chapter 6, Fan Operation.
When the operator changes the status of the fan, it will remain in that condition until the
operator changes the setting.
Summary of Contents for RUSKA 7050
Page 3: ...7050 Change Language Hold key for 5 seconds mode enter...
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Page 12: ...RUSKA 7050 7050i 7050LP Users Manual viii 7 1 Packing the PPI 7 3...
Page 18: ...RUSKA 7050 7050i 7050LP Users Manual 1 6...
Page 32: ...RUSKA 7050 7050i 7050LP Users Manual 3 4...
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