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Mass Flow Metering Systems: Dispelling the myths, detailing the benefits

MFMS shown to have delivered clear benefits in the face of measures taken in response to the pandemic, according to ExxonMobil and Bunkerspot research.

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This paper reviews the use of mass flow metering systems (MFMS) and dispels some of the myths surrounding their benefits and operations.

The use of mass flow metering systems (MFMS) is mandated by the Singapore marine port authority because of their ability to enhance the integrity and security of the bunkering process. They are also in widespread use in Hong Kong, the Amsterdam-Rotterdam-Antwerp (ARA) ports and in France, amongst other bunkering locations, but despite their growing adoption there remains some confusion about their benefits, such as the role they play in minimising bunker disputes.

These are just some of the findings revealed by new marine industry research, carried out by ExxonMobil and Bunkerspot, which asked maritime professionals from around the globe about their perception of the technology. Interestingly, MFMS were shown to have delivered clear benefits in the face of the measures taken in response to the pandemic.

Armelle Breneol
Marine Fuels Technical Advisor
ExxonMobil

 

A quick dip into the basics

In line with the marine fuels industry’s practice of predominantly selling fuels by mass, not volume, a MFMS directly measures fuel mass, removing the need for complex conversions using traditional measurement methods. It operates on the principles of the Coriolis Effect, which refers to the deflection of moving objects when viewed in a rotating reference frame. In the meter, fluid passes through two u-shaped tubes, which twist as a result of the flow. The angle of deflection from the vibration plane is used to establish flow calibrations.

A major advantage of the system is that the three variables in the refuelling process are independently monitored – direct mass flow, density and temperature. For example, monitoring density can help pick up air in the line. This could create air bubbles and affect measurement readings that traditional methods, such as manual dipping, can sometimes miss.

A mass flow meter, which has no mechanical moving parts, can be used for more than six years in the marine environment with minimal maintenance cost. In Singapore, some meters have actually been in use for eight to nine years. However, based on a conservative six-year usage, the cost per tonne can be as low as USD$0.17 per metric tonne when using a well-maintained MFMS, over and above any other tangible benefits.

To ensure integrity and security across the entire refuelling process, a MFMS should be independently accredited. This should cover information systems, equipment sealing and independent system audits by port authorities or third parties.

The proven benefits

This provides a wide range of benefits to vessel operators, marine industry suppliers and regulatory bodies. These include:

  • Enhanced transparency – reducing the uncertainties associated with density, temperature and other factors such as tank geometry. A MFMS is accurate to within +/- 0.5%
  • Significant cost benefits – saving up to an estimated US $4,650* per fuel delivery by eliminating the possibility of human calculation errors from traditional tank dipping
  • Significant time savings – offering the potential to save up to three hours per delivery**
  • Enhanced system integrity – with independent certification of the calibration and security of the system’s associated pipelines, valves, gauges and barge equipment. Tamper-evident seals are also installed throughout
  • Increased traceability – with data logged throughout the entire delivery process, illustrating the fuel mass transferred at any point in time, offering a transparent and accurate measure of delivered fuel

Taking a sounding

In order to better understand the marine industry’s grasp of the technology, ExxonMobil invited a range of maritime professionals to reflect on their experience and opinions around the use of MFMS. Replies were received from across Europe, Africa and South America; respondents represented charterers, vessel owners, bunker suppliers and surveyors. The results were highly informative.

All but one respondent had experienced a bunker dispute of some sort – around 50% said they were common. The remainder of the sample said they happened but were infrequent. What was revealing were the perceptions of the cost of an average bunker dispute; estimates ranged from around US$1,000 up to US$50,000 per stem. When asked to list the ports where bunker disputes are most common ARA ports were named many times. Singapore, which mandates the use of MFMS, wasn’t mentioned once.

Stemming the losses

When discussing the percentage of bunker quantity issues that go unchallenged by vessel operators, 38% of the sample said at least half. The reasons given for this included a shortage of time, an absence of manpower, a lack of willingness amongst crews to challenge barge operators and an inability to gauge a bunker. “It is very difficult to get an accurate manual tank measurement onboard receiving vessels,” explained a bunker supplier from the sample group.

When asked if vessel operators were prepared to ignore bunker shortages if the price of the fuel from that supplier is significantly lower than others, the split was equal; 43% of respondents answered either ‘yes’ or ‘no’ with the remainder unsure. Where there was more agreement was over the best ways to settle a bunker dispute: investigate the issue and raise a claim against the fuel supplier was the preferred option, although it was pointed out by some respondents that hiring a surveyor was a valuable defence against shortfalls. “I always have a bunker quantity surveyor present during bunkerings. The surveyor settles all disputes, if any, on site,” said one ship owner.

Just 19% said they would inform the authorities (port administrators, police etc.) of a bunker quantity dispute. Significantly, all of the respondents saw the value in maintaining transparency during the bunkering process.

Keeping the meter running

Eighty-seven percent of the sample group had experience of bunkering using a MFMS, although the understanding of how they work ranged from ”basic” and “minimal” to “it’s an entire system that utilises the advantage of a MFM but it must be a closed system that eliminates the possibility of cheating”. Another suggested that “as long as the entire operation, device and parameters are certified, it reduces the risk of fraud”.

However, opinions of MFMS varied quite widely. One bunker supplier said: “They’re a good thing and other places should use them, not only Singapore.” A ship owner remained unconvinced by their veracity. “We still need to be careful in assessing the delivery operation on barge side. As such, the surveyor is playing his role and checking vessels before and after the delivery,” they explained. A surveyor based in Europe believed they “were good to have” as they provide greater transparency during the bunkering process but they are also “an escape for suppliers”.

Ending the disputes

The sample group was then asked if MFMS could make bunker quantity disputes a thing of the past – 40% said ‘yes’ while 27% said ‘no’; the remainder were ‘unsure’. Despite this, 87% said they would support the mandating of MFMS around the globe as has happened in Singapore. One of the respondents who didn’t support their wider use said: “In ARA ports, barges are already equipped with reliable systems.” The respondent was a surveyor based in ARA.

The final question concerned the role of MFMS during the pandemic as a result of the restrictions brought in to tackle the spread of the virus, such as contactless bunkering. An increase in quantity disputes was highlighted by 38% of the sample; a further 44% was unsure. Many of the respondents were therefore supportive of the use MFMS as “surveyors can’t always board the barge, it’s difficult for them to find missing quantities”.

This drawback was confirmed by other replies. “The problem is that surveyors cannot board the bunkering barge to verify soundings,” said a South American ship owner. And according to Netherlands-based surveyor: “Barge operators don’t allow surveyors onboard, not even with the correct papers or negative Covid test.”

Lobbying for mass acceptance

Clearly, there’s an appetite for the greater use of MFMS even if there are still some gaps in the understanding of the core technology. ExxonMobil supports the use third-party accredited MFMS and will continue to implement the technology on its barges, where feasible, to ensure customers receive an efficient and transparent bunkering service without compromising on safety.

To find out more about ExxonMobil’s award winning MFMS visit: https://www.exxonmobil.com/en/marine/technicalresource/marine-resources/marine-fuels-mass-flow-metering-system

*Per 1,000MT stem size delivery at $450/MT. Includes surveyor costs, temperature delivery range and density delivery range but does not include dip tank measurement errors. A temperature measurement delta of 10°C amounts for up to US $3,150. A 3kg/m3 density difference amounts for up to US $1,500. These variables can be avoided by the use of a secure mass flow metering system, therefore negating the need of a quantity surveyor, with an estimated cost of up to US $2,000.

**comparison versus manual tank gauging

 

Photo credit: Manifold Times
Published: 12 January, 2022

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Bunker Fuel

Alkagesta highlights key insights on European choke point pressures in August

Update covers dual supply crisis currently shaping global bunker markets — a stalled Strait of Hormuz peace process and Rhine water levels at a 140-year record low — and the implications for Singapore.

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Alkagesta

Malta-based global commodity trading house Alkagesta recently shared latest market insight examining the dual supply crisis gripping global energy markets as diplomatic efforts to reopen the Strait of Hormuz stall and Rhine water levels fall to record lows, creating what the company describes as a “state of emergency” for European inland fuel distribution.

In an article published on Alkagesta Market Insights on 11 August, the company’s trading and market intelligence teams outlined how the convergence of two simultaneous logistical crises is tightening prompt fuel availability across Singapore, Northwest Europe, and the Mediterranean:

Strait of Hormuz transits fell to a near-one-month low of 13 ships on August 9 following an attack on an ADNOC-linked tanker, as both the US and Iran demand war reparations before any reopening agreement can be reached. Simultaneously, Rhine water levels at the Kaub chokepoint fell to 16 cm on August 10 — the lowest since records began in 1880 — with forecasts pointing to a further drop to just 4 cm by August 14, effectively halting barge traffic and trapping fuel oil stocks at the ARA hub.

The supply picture across both key hubs has deteriorated sharply. In Singapore, Middle Eastern fuel oil imports nearly tripled week-over-week to 328,878 mt by July 29 — the highest volume since March — providing some relief as onshore commercial heavy distillate stocks rose to a five-week high of 19.58 million barrels by August 5. However, July bunker fuel sales are estimated to have fallen 3.7% month-over-month to 4.44 million mt, with elevated premiums redirecting prompt demand toward alternative ports including Zhoushan and Port Klang.

In Europe, the VLSFO market remains acutely undersupplied as refiners continue to prioritize high-margin diesel over low-sulfur blending components, while the Rhine crisis has forced barges to operate at just 15–20% of normal capacity — with freight rates from Rotterdam to Karlsruhe rising more than 400% in two months.

Alkagesta’s strategic outlook points to a potential total breakdown in Rhine-linked inland distribution by mid-August, a VLSFO Hi-5 spread likely to remain above $200/mt through Q3, and a global crude market that analysts warn requires an additional 2.1 million b/d for 18 months to rebuild depleted inventories.

Note: The full article can be read here.

 

Photo credit: Alkagesta
Published: 17 August, 2026

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Bunker Fuel

Integr8 Fuels: Why bunker markets could be lower than we thought

Marine fuel prices could prove lower than previously anticipated as easing refinery margins and improving bunker market fundamentals outweigh a still-uncertain crude oil outlook, says Integr8 Fuels.

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By Steve Christy, Expert Contributor, Integr8 Fuels

29 July 2026

We have just seen one false dawn, is there another to come? 

Last month, we wrote about how close we were to the expected lows in Brent and Rotterdam bunker prices, but not yet Singapore. Given what has happened since, a month is not only a long time in politics, but also a very long time in the bunker market. 

There was a resumption of attacks in the Arabian Gulf region on 13 July, followed by targeted Houthi attacks on Saudi Arabia’s Red Sea oil infrastructure and shipping in the Bab el-Mandeb region, the gateway between the Red Sea and the Gulf of Aden. As a result, Brent futures fell to lows of around $70/bbl in late June and early July before surging to a high of $100/bbl on 23 July. Over the same period, Singapore VLSFO fell to $635/mt before climbing to $865/mt, a swing of $230/mt in just 16 days. 

Jul 2026 Graph 01 1024x613 1

Prices at the start of this week fell sharply after a halt in Arabian Gulf attacks over the weekend, with front month Brent was down to intra-day lows of $84/bbl, and Singapore VLSFO $750/mt.  However, at the time of writing there has been a ‘surprise’ attack by Iran, and retaliatory action by the US, with prices rising again.  It looks like we could be at another false dawn. 

The obvious questions are: will there be a return to peace negotiations, and are we close to the end of the war and free-flowing traffic through the strait of Hormuz (and also the Bab el-Mandeb)? The obvious answer is, we don’t know; there are only a few people that are likely to know the answer to this. All we can do is plan for every eventuality. 

Low stocks, higher bunker prices, and a strong Singapore VLSFO premium: it’s a challenge 

For those of us in the bunker market, the point we made last month about Singapore VLSFO trading at a strong premium to crude still holds, albeit slightly less pronounced. The loss of supplies through the Strait of Hormuz, together with the added uncertainty surrounding Saudi product exports from the Jizan and Rabigh refineries on the Red Sea, has sustained this premium. 

These developments are likely to keep the Singapore VLSFO premium to crude at elevated levels until there is greater confidence that Middle East crude and product supplies are returning to more normal trading patterns. Amid all the price volatility, this Singapore VLSFO premium remains a key indicator to watch. 

Backwardation in Brent futures illustrates market psychology 

One month ago, backwardation in Brent futures (front month minus second month) had fallen from $7/bbl to virtually nothing, reflecting the market’s belief that an end to the war was little more than a negotiating step away. It wasn’t. The resumption of attacks, coupled with Houthi involvement in the Red Sea, sent prices sharply higher again, with backwardation in the Brent futures market returning to almost $6/bbl. 

Jul 2026 Graph 02 1024x572 1

The halt in attacks over the past weekend has taken steam out of the market, with prices and backwardation falling sharply. Where we go from here depends if there is again a belief peace is on the horizon, or if this is another false dawn. The past month highlights how impossible it is to predict an ending to the war, and how fragile any expectations of peace can be. 

We cannot ignore the price, but still must look to the future

It is impossible to write a report and not highlight the turmoil of the current market and what is happening. However, we still must look beyond this, to see where we could end up. 

In an earlier report, we suggested the run-up to the US mid-term elections in November may be a backstop to the war. However, even this is not guaranteed. There are many dynamic elements to the economy and voter intentions, but one feature that will always crop up in the US is the gasoline price. This has risen from $3/gallon before the war to over $4/gallon for the past four months. 

Jul 2026 Graph 03 1024x570 1

If it comes to it, will Republican voters want to see a resolution to the war and a return to $3 gasoline prices ahead of the elections? 

We have a change of heart on how low bunker prices can go

We don’t know exact timings, but in any planning, we must look at what happens when the war does finally end and prices fall, whenever that may be. In past reports we have highlighted the view that Brent crude prices are unlikely to fall back to pre-war levels in the $60s, and Singapore VLSFO unlikely to go back in to the $400s. This may be the point at which these views change.

Previous thinking was based on a relatively short war, where there would be a large loss of oil supply and a massive stock-draw. In this case, tighter stock levels would be sufficient to keep prices higher than their pre-war levels once we returned to ‘normality’. This would mean Brent futures in the $70s (and not in the $60s), and Singapore VLSFO in the $500s, and not the $400s.

A number of mainstream analysts also held this view, although there were some that were lower and some higher.

Given the war has already gone on for much longer than almost everyone expected, this thinking must change. Yes, global stocks have been drawn down at a rapid rate, but this is slowing. Higher pricing and inflationary blows have had a major impact on global oil demand, with current indications that total oil demand in the second quarter of this year was some 4 million b/d lower than year earlier levels.

The graph below shows this sharp drop in demand and even if the war comes to an end relatively soon, and demand gets back towards some normality, a structural loss of more than 1 million b/d in global oil demand is still expected to have taken place because of the extended period of conflict.

If the war goes on for even longer, structural losses in global oil demand are likely to be even greater.

Jul 2026 Graph 04 1024x579 1

Source: US EIA

It’s a hard road, but we can get there

This means that once the war does end, market psychology will be looking at a rapid increase in oil supplies going into a global market which is much lower in demand.  This opens the way for prices to easily return to their pre-war levels of Brent in the $60s and Singapore VLSFO in the $400s. 

Now we just need those at the centre of negotiations to get us there.

 

Photo credit and source: Integr8 Fuels
Published: 30 July, 2026

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Bunker Fuel Quality

FOBAS report warns of growing operational risks from ISO-compliant bunker fuels

LR’s latest FOBAS Fuel Quality Report reveals that the biggest fuel quality risks are no longer confined to off-specification fuels, with some compliant fuels creating operational challenges.

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New FOBAS report warns growing operational risks from ISO-compliant bunker fuels

Classification society Lloyd’s Register (LR) on Tuesday (14 July) warned that ship operators are facing a growing risk from fuels that appear compliant under routine ISO 8217 testing but still present operational risks once onboard.

According to LR’s latest Fuel Oil Bunker Analysis and Advisory Service (FOBAS) Fuel Quality Report, covering the first half of 2026, off-specification fuels remain a persistent challenge. 

However, some of the most disruptive cases now involve fuels that pass routine compliance testing but show poor stability or compatibility, or contain non-conventional blend components that are only identified through more detailed investigative analysis.

Several incidents investigated highlighted this trend. In March and April, a number of vessels reported operational difficulties after bunkering fuel in a major bunkering hub. Further forensic analysis found that many of the fuels contained elevated concentrations of Estonian shale oil, in some cases estimated to be around 10-15%.

While shale oil is recognised within ISO 8217 as an acceptable blend component, FOBAS investigations found that higher concentrations can be associated with fuel instability and operational issues affecting filters, separators and fuel pumps.

The report also shows that fuel quality variability remains stubbornly high. Off-specification cases remained elevated throughout the first six months of 2026, suggesting that quality issues are no longer isolated events but a more persistent feature of today’s marine fuel supply chain.

The most common recurring issues included sulphur exceedances, excessive water content, sediment and stability problems, elevated catalytic fines, sodium contamination and low flash point distillate fuels.

At the same time, biofuels (especially FAME blends) are continuing to grow without being a primary source of quality issues. Where issues occurred in blended fuels, they were generally associated with the conventional VLSFO component rather than the FAME fraction.

The report concluded that operators will need to adopt a more proactive approach to fuel management as marine fuels become more diverse and fuel quality risks become harder to identify through routine compliance testing alone.

Greater emphasis on fuel stability, compatibility and understanding fuel composition will be critical to reducing operational disruption and maintaining vessel performance.

Murray Kirkwood, Fuel Specialist Consultant, Lloyd’s Register, said: “The findings from our latest report show that fuel quality risk is evolving. The challenge is no longer simply identifying fuels that fail specification. Increasingly, operators are encountering fuels that meet the required limits but still create operational difficulties once they are stored, handled and used onboard.

“As fuel blending becomes more complex, the distinction that matters is increasingly not between on-spec and off-spec fuel, but between fuels that are operationally resilient and fuels that are operationally fragile. Understanding that difference is becoming essential for shipowners and operators.”

The latest findings reinforced FOBAS’ long-standing view that effective fuel management increasingly depends on understanding fuel behaviour rather than relying solely on pass-or-fail specification testing.

By combining routine fuel quality monitoring with forensic investigation of operational incidents, FOBAS provides shipowners with a clearer understanding of emerging fuel quality risks as the industry continues its transition to a more diverse and complex fuel landscape.

Note: The FOBAS Fuel Insight: Fuel Quality Report H1 2026 is available at FOBAS Fuel Insight: Fuel quality reports | LR

 

Photo credit: Lloyd’s Register
Published: 15 July, 2026

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