Usage Notes
- The sensitivity is calibrated with nitrogen. If the main component of the residual gas is not nitrogen, the value will be different from the actual pressure.
- In the measurement of gases, including oxygen and water vapor, the filament reacts to them and deteriorates severely.
To prevent it from being worn out, it is necessary to lower the emission current or to use a thoria-coated filament. - When measuring the pressure below 10-4Pa, degassing of the sensor head itself is necessary.
When degassing, the pressure becomes high due to a large amount of emitted gas, the sensor head may become dirty. Degassing must be performed at 10-4Pa or less. - If it is continuously used at high pressure (Triode type:10-1Pa or more), the filament wears out, and a constant emission current cannot be obtained.
Trouble checklists
1. The filament of the sensor head does not turn on
2. The filament of the sensor head is lit abnormally (Brighter than usual)
3. The filament turns on, but the pressure is not displayed
4. The filament turns on for a moment but then turns off immediately
5. The measurement value drifts
6. The measured pressure differs largely from expected value
7. Set point signal is not given
1. The filament of the sensor head does not turn on
| Causes | Solutions |
|---|---|
| The filament has worn out | Replace the sensor head |
| The sensor head cable is broken | Repair or replace the sensor head cable |
| High pressure | Check the pressure with a Pirani gauge |
| The setting error of filament selection switch | Select the correct filament |
2. The filament of the sensor head is lit abnormally (Brighter than usual)
| Causes | Solutions |
|---|---|
| The sensor head cable is broken | Repair or replace the sensor head cable |
| The controller is broken | Request repair |
| Degradation of the sensor head | Replace the sensor head |
3. The filament turns on, but the pressure is not displayed
| Causes | Solutions |
|---|---|
| The sensor head cable is broken | Repair or replace the sensor head cable |
| The controller is broken | Request repair |
4. The filament turns on for a moment but then turns off immediately
| Causes | Solutions |
|---|---|
| Filament protection is activated due to high pressure | Check the pressure with a Pirani gauge |
| The controller is broken | Request repair |
5. The measurement value drifts
| Causes | Solutions |
|---|---|
| Sensor head or sensor head connection part has a vacuum leak | Replace the sensor head or repair the vacuum leak of the connection part |
| The sensor head is contaminated | Replace the sensor head |
| The sensor head cable is vibrating | If the sensor head cable is always subjected to vibration, the indicated value may drift by the frictional electromotive force inside the sensor head cable. Re-examine the method of laying the cable. |
6. The measured pressure differs largely from the expected value
| Causes | Solutions |
|---|---|
| There is a leakage current | The sensor head is contaminated or the sensor head cable has insulation failure, so replace them |
| ・The sensitivity setting is incorrect ・The gas being measured is not nitrogen or atmosphere (air) |
Check the manual and set it correctly |
| The actual pressure differs from the expected value | Check with another vacuum gauge |
7. Setpoint signal is not given
| Causes | Solutions |
|---|---|
| Replacement of the relay in the controller | The relay is broken → Request repair. |
| The emission current of the sensor head can hardly be obtained normally | If the emission current is momentarily NG, the setpoint will also be turned OFF simultaneously. Replace the sensor head |
Causes of No Emission Current and Solutions
| Causes | Solutions |
|---|---|
| Pressure is high（10-1Pa or more） | Check pumping system |
| Filament burnout | Replace the sensor head |
| Filament wear | Replace the sensor head |
| Contamination in the sensor head | Replace the sensor head |
| Poor contact or burnout of sensor head cable | Re-connect or replace the sensor head cable |
| Failure of power supply circuit in the controller | Request repair |