If the FS1650 alarm is not operating properly, please use the following tips to identify and resolve the issue(s):

  1. At Start up, LED “GREEN”, audible alarm constantly on

2. Face velocity good, alarm LED “RED”, audible alarm continuously on

3. Face velocity good, alarm LED “RED”, audible alarm intermittent

4. Face velocity bad, alarm LED “GREEN”, no audible alarm

5. Alarm is not turning on, NO “GREEN” OR “RED” light indication.

6. Face velocity good, alarm LED “GREEN, audible alarm continuously on

NOTES

  1. A quick visual check may be performed to verify that the thermistors are not broken or shorted. This is the most common with the center measuring thermistor. It may become broken from damage that occurred during installation or cleaning. Due to its small size and sensitivity, the wires connecting it to the sensor’s PCB can become broken or bent. If the measuring thermistor has a broken wire, this will result in an open circuit. Either condition will cause a continuous alarm.
  2. Establishing the appropriate face velocity is one of the most important factors in the overall performance of the enclosure. Most vented enclosures from Flow Sciences are designed to operate with a face velocity of between 60 and 100 lfpm (0.3 – 0.5 m/s) and a recommended face velocity of 75 lfpm ± 5 lfpm (0.38 ± 0.02 m/s).

 

Flow Sciences recommends the face velocity alarm be set at 20% below the operational face velocity. Therefore, if 75 lfpm (0.38 m/s) is the desired velocity, the alarm should be set to activate at velocities below 60 lfpm.

Begin alarm calibration by first setting face velocity to desired alarm activation velocity.  Remove the four screws located on the face of the alarm. Next, set the delay to desired time by adjusting the delay screw.  Flow Sciences recommends setting this all the way to the right (30 seconds) so quick disturbances in the face velocity will not trigger the alarm.  Adjust the set point screw (shown in the image below), until the RED and GREEN lights toggle between each other. This sets the alarm so that a consistent (30 seconds) face velocity of, for example, less than 60 lfpm (0.3 m/s) will trigger the alarm.

3. If this guide suggested a replacement or your issue(s) remain unresolved, please call our office at (800) 849-3426 and ask for Technical Support. If the issue is not urgent, you may alternatively send an email to customersupport@flowsciences.com.

 

Sensor appearance

A quick visual check may be performed to verify that the thermisters are not broken or shorted.  This is most common with the center measuring thermister.  It may be become broken from damage that occurred during installation or cleaning.  Due to its small size and sensitivity, the wires connecting it to the sensor’s PCB can become broken or bent.  If the measuring thermister has a broken wire, this will result in an open circuit.  If the wires beneath the bead are touching, this will result in a shorted circuit.  Either condition will cause a continuous alarm.

Sensor Measurement

If an electrical multi-meter is available, initial resistance can be measured to give an indication of the integrity of the thermister.  When checking the thermister, remember that the meter is applying current through the components and resistance values will change as it heats up (*sensor must acclimatize to room temperature before proper function can be achieved*).  One needs to note only the initial value for this test.  Values for the thermisters are as follow:

Reference Thermister – 115k Ohms (95K – 120K possible range)

Measuring Thermister – 5K Ohms (4.5K – 7K possible range)

Cameron Faulconer is an Industrial Hygienist with a wide breadth of experience, spanning between commercial manufacturing, to home residences. His inspiration for his choice of career is communicating the value of preserving the health and safety of employees using the most effective and efficient means possible. Therefore, Mr. Faulconer found his place in the “Engineering Controls” rung of the hierarchy of hazard controls.

As a problem solver, Mr. Faulconer believes that the best safety solutions are created through consultative conversations with those who seek solutions. He believes communicating information derived from these conversations to be critical to the continued understanding of the toxicological impacts of the work environment.

His personal motto is “protecting the safety and health of employees from what can and cannot be seen with the naked eye”.