Detector Settings
System Sensitivity
The UV tube count rate generated by different fires at the same distance is unpredictable. Generally if a fire doubles in size, the tube response is increased by about 60 percent. The UVU-140-A & UVU-140-AR detectors have selectable sensitivity settings which allow for various applications regardless of the severity of the hazard and the action required if a fire occurs. The system can be adjusted to various sensitivity levels by setting the detectors to respond at a pre-determined detector count rate. The count rate is dependent upon the intensity of the ultraviolet radiation reaching the detector, which in turn depends on the type of fuel, temperature, flame size, distance from the detector and concentration of UV absorbing vapours present. Setting the UVU-140-A & UVU- 140-AR detectors to respond to a low count rate results in high system sensitivity. Adjustments are made by setting the DIP switch on the bottom of the internal module. The factory settings are 5 second time delay at 24 counts per second (cps), the fire relay is de-energized and latching.
Table 1 - Detector Sensitivity Settings
SYSTEM SENSITIVITY SETTINGS
| | Switch 1 | Switch 2 |
8 | Counts (cps) | ON | ON |
16 | Counts (cps) | ON | OFF |
24 | Counts (cps) | OFF | ON |
32 | Counts (cps) | OFF | OFF |
Figure 10 - DIP switch operation
System Time Delay | and location |
Time delay can be set via dip switches located on the bottom of the electronics module . See Figure 7.
Table 2 - Alarm Response Delay Settings
SYSTEM TIM E DELAY SETTINGS
| Switch 3 | Switch 4 |
3 Seconds | ON | ON |
4 Seconds | ON | OFF |
5 Seconds | OFF | ON |
7 Seconds | OFF | OFF |
Coil and Relay Settings
The DIP switch is located in the JBR-T assembly.