What action is required when the pressure differential gauge shows a red indication?

When the pressure differential gauge shows a red indication, it signifies that the filter separator is becoming clogged or is experiencing a significant pressure drop. This condition can lead to inefficient fuel filtration and potentially compromise the quality of the fuel being handled. As a response to this critical warning, changing the filter separator is essential to restore proper functioning and ensure safe operations. Additionally, submitting a sample of the fuel for testing is recommended to assess its quality and determine if contamination has occurred, which could have caused the clogging.

This action helps maintain the integrity of the fuel system and prevents further issues that could arise from continued operation under compromised conditions. Therefore, the necessary response involves both replacing the filter separator and evaluating the fuel quality through sampling.