-Alex Canney, Northeast Regional Office
In the middle of the week, we had a preventative maintenance service for a filtration unit scheduled in Maine (see Pic 1) and as we were walking in found out that a Massachusetts hospital had an urgent need for troubleshooting their fuel oil system. We were able to complete the work at the first hospital and then hit the road to be at the second in the early afternoon. From the phone calls it sounded like a suction line issue, which can be very tricky to nail down so we wanted to see and hear what was happening ourselves. The facility manager was not confident that the generator would have fuel if the hospital lost power overnight, and they do not have a 24 hour facilities staff. After reviewing the system and interviewing site personnel we were faced with a few challenges:
#1 The day tank was full and there was no way to remove fuel to allow additional fuel to be pumped.
#2 The suction side compound gauge was missing, so any cavitation/air entrainment investigation would be subjective at best.
#3 Positive flow proving was critical to troubleshooting and since we could only dump fuel back through the relief valves we lost the ability to use the flow proving switch, as its situated upstream.
#4 The older controls precluded learning anything from the “alarm history” (see Pic 2).
We went upstairs and reviewed the piping at the day tank — which would not be intuitive based on the information we already had — but experience has taught it is imperative to understand the entire system, not just the part that seems to be malfunctioning. We noticed on the day tank that the fuel riser pipes coming from below only went two places – the overflow connection on the side of the tank, and what looked like to a casual observer, a return pump. (See Pic 3) Those are both return fuel functions, which meant that either the supply line was piped to the overflow, or into a pump that may or may not be operating in forward or reverse at some point.
We went back down to the pumpset level and confirmed that the noise they heard, initially thought to be cavitation, was more of a whine than grinding. At this point we needed to get creative and we opened up a connection on the supply line and put a bucket underneath. We ran the pumps and they were whisper quiet – flowing like brand new. Then I closed the system back up and ran it as it normally does and observed the noise. It was the relief valves whining, which is common when most of the flow is diverted. This confirmed that the supply line to the day tank was piped into the pump we found before it got to the day tank, and had been like that for quite a while. Our pumps had actually been supplying fuel, the best they could, in a very bad situation. The generator representative and others had observed the system without noticing that issue for an extended period of time, but we were able to get them an answer in under an hour.
The immediate plan is to pipe around the pump at the day tank, with a longer term goal of buying a new system to update the aging equipment. They have looked into replacing the system in the past since it’s about 25 years old, but this will give them the urgency to free up the money form the budget.
Situations like this reemphasize the importance of looking at the system as a whole, being responsive to our customer’s needs, and the value of solving problems.