LEYBOLD 230070V02, Руководство по эксплуатации

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30 300544652_002_C1 - 11/2016 - © Leybold
FAQ (Frequently Asked Questions)
Applications
Q:
Can the transmitter and sensor element continuously withstand vibrations from a mechanical fore-pump?
A: Yes
– the MEMS Pirani sensor element can withstand continuous vibrations.
Q:
Is the transmitter compatible with fluorine gases?
A: No
– The transmitter is not intended for use in aggressive environments, like semiconductor etch applications.
Q: When the transmitter is pumped down and isolated by closing a valve the pressure is raising. Is the transmitter
leaking?
A:
Not likely - when a confined space is evacuated and the pumping is stopped the pressure will rise because of
outgassing, mainly by water vapor. The pressure can easily rise to a few mbar over time.
Q: When the transmitter is leak checked on a helium leak detector. Leak reading is building up slowly after
approximately 30 seconds. Is the transmitter leaking?
A:
No - the internal sealing of the PTR 90 N PENNINGVAC transmitter uses elastomer FPM sealing and
consequently helium molecules can permeate e through the FPM material and cause slow increase of helium leak
readout. If a leaking transmitter is tested directly on a helium leak detector the leak is almost instantly displayed.
Q: Can the transmitter be mounted in any orientation?
A: Yes - the transmitter can be mounted in any orientation without compromise of performance or calibration.
However it is recommended not to mount the transmitter with the flange port facing upwards to avoid contamination
like particulates or liquids from entering the device.
Q: Can the transmitter withstand instant ventilation?
A: Yes - the MEMS Pirani sensor and cold cathode elements are extremely robust to mechanical forces and can
withstand continuous pressure cycles and instant air ventilation.
Q: Can I connect a valve to be controlled by the transmitter relay contact?
A: Driving inductive loads such as valves requires special precautions. Refer to chapter 4.2.
Q: How many pressure cycles can the transmitter withstand?
A: Both the MEMS Pirani and cold cathode sensor elements are very mechanical robust to pressure changes and
the number of pressure cycles will have no effect on the lifetime of the transmitter. In applications where fast
pressure cycles occur, the cold cathode sensor can be sputtered and this can lead to change of accuracy.
Q: The cold cathode sensor chamber has changed color, Why?
A: If the cold cathode is operated at high pressure (>1.00E-4 mbar) the inside walls of the cold cathode ionization
cell can be sputtered. This will change the color of the internal measuring chamber and can also result in change of
measuring accuracy.
Analog output
Q:
What is the update rate of the analog output?
A: 16 times per second.
Q: What is the maximum length of analog output cable?
A: The length of analog cable depends on cable quality and electrical noise environment. Cable lengths up to 100
m do not normally require any special precautions other than the cable must be screened.
Q: The digital reading is correct but the analog output reading has some deviation from actual pressure?
A: Check that the analog out is connected to a floating input and not an input that is connected to ground. If
connected analog out return is connected to ground, the supply current will flow in the signal line and cause voltage
drop and ground looping.
Q: Can I get an analog output for the Piezo signal?
A:
Yes
– the analog output can be configured to any of the sensor signals (for RS232 versions only). Refer to
analog output set up.
Digital output
Q:
How fast can I request pressure measurements via the digital interface?
A: 10 times per second is the fastest recommended pressure request frequency.