Maintenance; Contamination - Instrutech The Hornet IGM402 User Manual

Instruction Manual
Indication
Filament voltage values are
present for several seconds
immediately after turning IG ON,
but then the values are zero
All parameters in the R&D screen
are zero after IG turn ON is
attempted
IGM402 filament voltage is
greater than 1.7 V and filament
current is greater than 2.5 A with
emission current = 100 μA
IGM402 filament voltage is
greater than 2.3 V and filament
current is greater than 2.7 A with
emission current = 4 mA

Maintenance

9.6
In general, maintenance is not required for your InstruTech module. Periodic performance checks may be done
by comparing the gauge to a known reference standard. When using the transducer in gases containing
contaminants or materials that react with the filaments of the hot cathode ion gauge, periodic degas and
switching to the alternate filament from time-to-time is recommended for longest useable transducer lifetime.
When the hot cathode (filament) of the ionization gauge transducer is at or near end-of-life, transducer (sensor)
replacement is recommended.

Contamination

9.7
The most common cause of all vacuum gauge failures is contamination of the sensor. Noisy or erratic readings,
and total gauge failure are all possible indications of gauge contamination.
Contamination can be generally characterized as either a reaction of process gases with sensor elements, or an
accumulation of material on the sensor elements. Sensors that fail due to chemical reaction are generally not
repairable. Sensors that fail due to condensation, coatings, or particles may possibly be restored by performing
the degas function.
InstruTech
Possible Cause
Filament is contaminated or
filament has reached end-of-useful
operating life for required emission
current setting
Failed electronics
Filament nearing end-of-useful-
operating-life
Filament nearing end-of-useful-
operating-life
Possible Solution
Switch emission current setting from initial
setting and re-start the IG; make several
attempts to establish emission current at both
100 μA and 4 mA.
Switch to second filament or replace ion gauge
sensor
Replace the IGM402 electronics
Switch to second filament or replace ion gauge
sensor
IGM402 may be operated at either 100 μA or
4 mA emission current setting. If trouble with
maintaining 4 mA emission current (Ie)
persists, switch to 100 μA emission current.
For a marginal filament coating condition, you
may have to operate the emission current at
the 4 mA setting even if the maximum actual
emission current is less than 4 mA. This may
prevent an EMIS FAIL error that may occur
when attempting to turn on the filament with
emission current set at 100 μA.
IGM402 Hornet
Page 79