On March 2009, we upgraded our GE ultrasonic flowmeter from type of XMT868 to XMT868i and equipped with the surge arrester.
It was found that the fuse on the old meter electronic card was blown. After replaced the meter was OK. However, after that, the old meter was suddenly off temporarily, after which it was back to OK again and it happen several times.
Considering its important function to measure how many filtered produced water injected to the wells for enhanced oil recovery program, we decide to replace it with the new one equipped with the surge arrester as suggested by engineer from GE.