In the latest issue of its StopLoss Bulletin, the club explains that the cappuccino effect is essentially the frothing or bubbling effect caused by compressed air blown through the delivery hose. The aerated bunkers when sounded will give the impression that the fuel is delivered as ordered. In fact, after some time, when the entrapped air in suspension settles out of the fuel oil, the oil level drops and a shortfall is discovered.
The club says, “There are a number of ways in which cappuccino bunkers may be identified. These include signs of froth/foam on the surface of the fuel in the barge tanks when opening the gauge, and excessive bubbles on the sounding tape prior to, during and after bunkering. The bunker hose may also jerk or whip around, delivery rates may be slower than those agreed, and there may be a gurgling sound in the vicinity of the bunker manifold. There may also be fluctuations in pressure on the manifold pressure gauge, and unusual noises from the bunker barge.”
Outlining precautions that should be taken before fuel transfer takes place, the club explains, “During usual gauging of bunker barge tanks, fuel oil from ullage hatches should be visually checked for any foam on the surface. Foam may also be detected on the ullage tape. If entrained air is suspected on the tape or fuel surface, obtain a sample and pour it into a clean glass jar and observe carefully for signs of foam or bubbles. If the suspicion is confirmed, the chief engineer should not start bunkering and should notify the owners/charterers immediately.”
With regard to precautions during and after fuel transfer, the club notes, “Air can also be introduced in the fuel during the pumping period, so it is important to continue gauging the ship’s tanks, as air bubbles would be readily seen on the sounding tape. As stripping and line blowing can also introduce air, stripping should only be performed at the end of the delivery for a short period of time, and line blowing kept to a minimum. The ship’s bunker manifold valve should be checked shut before gauging of the ship’s tanks.”