Assessments - 2, GPA: 4.5 ( )

Fabricante : Gentek Arquivo Tamanho: 1.29 mb Arquivo Nome : Língua de Ensino:

The PCB has also a two-pin connector for use as an external output with isolated relay contacts that close when the red/alert LED is lit (low airflow). These relay contacts are not affected by the “SILENCE ALARM” button. The PCB is mounted behind the front panel using standoffs and an appropriate label is used to highlight the “SILENCE ALARM” button with clear areas for the red and green LED’s. No holes to allow sound to be broadcast louder are necessary. The PCB can be prepared as a factory special with an additional connector for the following external inputs, and having the following possible functions: Chapter 6: Maintaining Your Filtered Enclosure • External Alarm allows an external signal to sound the alarm, such as a sash open switch, or a “fail” signal from the building airflow system. • Alarm Disable allows an external signal to prevent a “low” airflow alarm from occurring. • Night Setback allows an external signal to prevent a “low” airflow alarm from occurring (not any different from Alarm Disable above other than the terminology.) Contact Labconco for ordering information on this special PCB. Calibration 1. Ensure the flow switch and alarm circuit board are installed and operational. 2. Allow the enclosure to operate for at least two minutes. 3. If factory installed, the monitor will alarm at 60±10 fpm with the inflow velocity set at 90±10 fpm. 4. To change the factory setting, set the inflow velocity required by your Safety Officer to the desired alarm condition using the speed control adjustment procedure outlined in Chapter 6. 5. Once the alarm condition is set, use a small screwdriver to turn the adjustment screw on the airflow switch counterclockwise (facing the screw) until the “low” airflow red LED lights and the audible flow alarm sounds. 6. Adjust the inflow velocity to the nominal operating point required by your Safety Officer. 7. Over time the HEPA filter will load and eventually slow the inflow velocity. Once the alarm condition is met, simply increase the speed control outlined in Chapter 6 or replace the HEPA filter if the speed control is maximized. 8. The table below lists typical alarm conditions based on normal operating conditions. Typical alarm conditions are set at face velocities of 10 to 30 feet per minute below the normal operating conditions due to supply air and exhaust air fluctuations, as well as room air cross drafts. Consult your Safety Officer for proper operating speeds. Enclosure Operating In-Flow Speed Alarm Condition Set Point Speed 100 ± 10 fpm 70-90 fpm 90 ± 10 fpm 60-80 fpm 80 ± 10 fpm 50-70 fpm 70 ± 10 fpm 50-60 fpm 60 ± 10 fpm 50 fpm 51 Chapter 6: Maintaining Your Filtered Enclosure Option Figure 6-2 Guardian Airflow Monitor (LED) with Airflow Switch Guardian Digital 1000 Airflow Monitor Refer to Figure 6-3 for operation and calibration. Refer to the separate Labcon...

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