EN
Marine Fuel Flow Meter Manufacturer
Time : 2025-10-09
1.The Importance of Ship Fuel Flowmeters
Ship fuel flowmeters, as key tools for accurately measuring fuel consumption by energy-consuming equipment such as main engines, auxiliary engines, and boilers, play a vital role in shipping companies. They not only accurately calculate equipment energy consumption but also serve as a core basis for evaluating equipment efficiency. However, despite their indispensability in ship operations, a lack of unified standards for ship design and flowmeter installation has led to frequent metering issues.
Analysis of Fluid System Pressure Constraints
Parameter Symbol |
name |
The core role of engineering scenarios |
Core formula |
P out≥（3 X P dp）+P vp |
A core pressure safety/performance constraint in engineering (especially in fluid transport and pressure equipment design, such as pumps, valves, and instrumentation systems) to ensure stable system operation and avoid failures (such as cavitation and instrument failure). |
P out |
Outlet pressure
|
It refers to the "output pressure of key nodes" of the system (such as the outlet pressure of the pump, the pressure behind the valve, and the pressure at the outlet of the container), which is the "active pressure" that can be controlled by the system. |
P dp |
Pressure loss at instrument |
It refers to the pressure loss caused by the internal flow resistance of the instrument when the fluid flows through the "measuring instrument" (such as a pressure gauge, flow meter, pressure transmitter) (similar to the pressure drop in a water pipe filter), which is the "passive pressure loss" of the system. |
|
P vp
|
Medium flash pressure |
This refers to the medium's "saturated vapor pressure"—the critical pressure at which the medium transitions from liquid to gas at a specific temperature (the higher the temperature, the greater the Pvp). If the local system pressure falls below the Pvp, the liquid medium can suddenly flash to gas, creating bubbles (potentially causing cavitation and vibration). |
Currently, the International Maritime Organization, government authorities, and other industry organizations have yet to establish mandatory, unified regulations for flowmeter design, installation, inspection, and maintenance. Consequently, flowmeter design and manufacturing are primarily based on regional safety standards (such as the EU Pressure Equipment Directive (PED) and ATEX explosion-proof certification), while their installation and use often adhere to the manufacturer's own standards. This decentralized management model leads to numerous issues in the design, installation, and operational management of current flowmeters, seriously impacting the integrity, accuracy, and effectiveness of measurement, and failing to fully meet the metering needs of ships.
1.1 Incomplete Data from Equipment Measurement
One of the main challenges facing existing fuel flow metering systems on ships is that flow meters are typically installed for main and auxiliary engines, but boilers, due to their low frequency of use and relatively low fuel consumption, are rarely equipped with flow meters, resulting in incomplete metering data. A ship's energy-consuming equipment includes the main engine, auxiliary engines, boilers, and incinerators. During the design and construction phases, designers, builders, and shipowners often prioritize cost-effectiveness and install separate flow meters for the main and auxiliary engines, while overlooking the metering needs of boilers.
2.Fuel Metering Issues
2.1 Impact of Backwash Filters
In the design of a certain ship's main engine fuel supply unit, the backwash filter was placed downstream of the flowmeter. This design can lead to metering errors: because the flowmeter is located upstream of the filter, when the backwash filter is activated, the flushing fuel must first flow through the flowmeter before entering the filter. This causes the flowmeter to count unburned flushing fuel as consumed. For example, statistics on the backwash filter flushing volume of a 180,000-ton bulk carrier's main engine fuel supply unit show that approximately 0.34 tons of fuel is not burned daily, accounting for 0.86% of the measured fuel consumption.
2.2 Unmetered Return Oil Pipelines
Large main and auxiliary engines, boilers, and other energy-consuming equipment on board ships often use heavy fuel oil (also known as intermediate fuel oil, primarily a mixture of refinery residue and diesel). In the fuel circulation system, the return oil pipeline is not equipped with a separate flowmeter, and the return oil must pass through a three-way valve—one portion is returned to the oil collection drum for recycling, and the other portion is delivered to the equipment. If the three-way valve is not tightly closed or accidentally opened, fuel already metered by the fuel supply flowmeter will flow back without entering the equipment for combustion, causing counting errors and affecting overall metering accuracy.
3.Flowmeter Placement Options
3.1 Placement at the Fuel Daily Tank Outlet
Placing a flowmeter at the fuel daily tank outlet directly measures total fuel consumption for the entire ship. This solution is simple and economical. However, it is important to note that the flowmeter's operating conditions (such as compatibility with the medium temperature and viscosity) and pressure differential must meet system requirements (for example, pressure constraint logic must be followed to ensure that the outlet pressure offsets instrument pressure drop and prevents medium flashing) to ensure accurate metering.
3.2 Placement in the Fuel Supply Unit
The core function of the fuel supply unit is to provide a stable fuel supply to the main and auxiliary engines; metering is an additional requirement. In this type of system, the flowmeter should be installed downstream of the booster pump and upstream of the circulation pump. The booster pump ensures stable fluid pressure, while the circulation pump prevents fuel stagnation. This placement minimizes the impact of pressure fluctuations on metering. The layout option should be determined based on actual needs. If the main and auxiliary engines share a fuel supply unit, flow distribution balance must be considered. Separate fuel supply units can further improve the metering accuracy of individual devices.
3.3 Installation on Equipment Inlet and Outlet Pipelines
Installing flow meters directly on the fuel inlet and outlet pipelines of energy-consuming equipment such as the main and auxiliary engines and boilers allows the difference between "inlet flow rate - outlet flow rate" to be used to calculate the equipment's actual fuel consumption (eliminating interference from uncombusted fuel such as return fuel and filter flushing), significantly improving metering accuracy. However, this solution requires two separate flow meters for each device, which is more expensive. Compared to other layout options, this solution reduces uncertainties in intermediate piping links (such as the influence of filters and valves), ensuring high metering accuracy.
4. JUJEA Flowmeter Selection and Installation Recommendations
4.1 Selection Considerations
When selecting a flowmeter, consider the following parameters based on the specific layout plan:
① Fuel type and viscosity;
② Rated flow range (must match the equipment's maximum/minimum fuel consumption);
③ Operating pressure level (must be correlated with instrument pressure drop to ensure system pressure meets metering requirements);
④ Medium temperature range (must match the medium's flash pressure to avoid flash evaporation-induced metering distortion). Furthermore, the counter should be selected based on actual needs. Its functions should include energy consumption data statistics, data storage, and standard output formats (such as RS485 and 4-20mA signals) to accommodate the ship's energy efficiency management system.
4.2 Installation Key Points and Precautions
Flowmeter installation must comply with relevant standards (such as the International Maritime Organization's "Guidelines for Calculating the Energy Efficiency Operational Index (EEOI) for Ships" and the equipment manufacturer's installation manual) to avoid incorrect site selection and connection. The following requirements must be met during installation:
① The base must be a rigid structure and be firmly fixed to prevent vibration from affecting the metering components;
② The installation angle must be determined according to the type of flow meter (e.g., turbine flow meters must be installed horizontally to avoid bubble retention);
③ Sufficient straight pipe sections must be reserved before and after the flow meter (usually the length of the front straight pipe section is ≥10 times the pipe diameter, and the length of the rear straight pipe section is ≥5 times the pipe diameter) to reduce flow field disturbance;
④ The seals must be adapted to the fuel type to prevent leakage.
5.JUJEA Manufacturer's Maintenance and Care Standards Guide
5.1 International Regulatory Requirements
According to international regulatory requirements, the calibration and maintenance of flow meters must comply with the specific provisions of the "2016 Guidelines for the Development of Ship Energy Efficiency Management Plans" (MEPC.282 (70) Resolution): ① The calibration cycle shall not exceed 24 months; ② Maintenance records must be included in the ship's energy efficiency management file to ensure data traceability; ③ The measurement error must be controlled within ±1% to ensure data accuracy and reliability.
5.2 Maintenance
Flowmeter maintenance must strictly follow the manufacturer's instructions. Routine maintenance includes:
① Main unit maintenance (cleaning the sensor, checking seal integrity, and tightening connecting bolts);
② Metering accuracy calibration (using calibration against a standard flowmeter). Regular calibration can be performed based on the equipment load to provide a preliminary assessment: compare the equipment's theoretical fuel consumption (calculated based on power and fuel calorific value) with the flowmeter's reading. If the deviation exceeds ±2%, prompt maintenance is required. During annual inspections or dry docking, a professional calibration must be performed by an onshore testing agency with maritime metrology certification (such as China CNAS or the European Union CE certification) to ensure the flowmeter's accurate measurement function.
