Temperature and viscosity in bitumen metering are managed by holding the meter, and the whole metering run around it, at a stable temperature inside the product's safe handling window. The meter body, strainer, valves and flanges are heated by a jacket or by heat tracing; the metering technology is chosen to tolerate high viscosity and temperature swings; and the gas that enters the line at the start and end of a transfer is dealt with explicitly. General heated-skid engineering, such as cold spots, heating control and insulation, is covered on the heated metering skids page for heavy oil and fuel oil. This page focuses on what is specific to bitumen.
What makes bitumen hard to meter
· High operating temperature: Bitumen is loaded hot; Eurobitume refers to loading temperatures up to 200 °C for paving grades and up to 230 °C for oxidized bitumen. Sensors, seals and electronics must be rated accordingly.
· Viscosity that tracks temperature: The viscosity of petroleum products changes sharply with temperature, so modest cooling shifts pressure drop and meter behavior. Product left to cool inside a meter can solidify.
· Gas and air: In one manufacturer case study on polymer-modified bitumen loading, outgassing caused the previous meter to deviate noticeably from the weighbridge. Unloading applications also see air entering at the start and end of the transfer.
· Overheating: Heating surfaces that run too hot can cause coking and deposits, which in meter tubes and narrow passages also affect the measurement.
Choosing the metering technology
Coriolis mass flow meters and positive displacement (PD) meters are the options most often considered for bitumen. The choice depends on whether the commercial quantity is mass or volume, on the viscosity range and on the maintenance approach.
· Coriolis mass flow meter: Measures mass directly and provides density, so bitumen can be delivered on a mass basis without converting a temperature-sensitive volume. Manufacturers offer heating jackets and steam kits for their sensors. Pressure drop rises with viscosity and accuracy can suffer at low flow, so the meter is sized to run in the upper part of its range.
· PD meter: Higher viscosity reduces internal slippage but raises pressure drop, which loads bearings and seals. Operating viscosity should be close to the calibration fluid's viscosity to avoid measurement error, and a strainer may be needed for solids.
· Weighbridge: Many bitumen sites set the delivered quantity from loaded and empty vehicle weights. The meter then serves preset loading control and in-plant monitoring.
Some published industry guidelines on meter selection for road and rail loading gantries explicitly exclude heated and heavy products. Practices that are well established at white-product terminals should not be transferred to bitumen as-is; they need to be checked against the meter manufacturer's high-temperature and high-viscosity data.
Heating the meter body and the skid
For Coriolis sensors, manufacturers offer heating jackets made of two half-shells that enclose the sensor housing. The jacket is fed with a heating medium such as thermal oil, steam or hot water and keeps the sensor temperature stable. Allowable heating-medium pressure and temperature are set by the manufacturer and must match the site's heating utility.
Unlike the sensor, the transmitter electronics have a limited ambient temperature rating. Where the hot body and insulation could overheat them, a remote-mount version or one with an extended neck for insulation is used. Strainers, valves and temperature and pressure connections on the skid are heated by electric or steam tracing; electric trace heating follows different standard families in hazardous and non-hazardous areas. Insulation should be removable for maintenance.
Zero stability and temperature effects
A Coriolis meter's zero can shift with temperature. For services like bitumen that run far above ambient, it is common engineering practice to perform or verify the zero at operating temperature with the meter completely full, flow stopped and free of gas. Some manufacturers state that they calibrate meters for high-temperature service at several temperatures. Keeping jacket and line temperatures steady limits zero drift and fluctuations in the density reading.
Handling gas and laying out the run
· Locate the meter where it stays full even when the line drains, preferably at a low point, with a downstream control valve holding enough pressure in the meter.
· Bitumen loading guidance calls for slow start and slow finish via the flow control valve; that ramping also softens the start and end phases where the meter is under most stress.
· Meters with entrained-gas diagnostics and handling functions deserve particular attention for polymer-modified bitumen.
· The density signal can be passed to the control system to monitor product consistency and spot abnormal gas entry.
Quantity calculation and records
Bitumen may be traded on mass or on volume. Converting between the two requires the temperature-dependent density of the bitumen, which should come from the supplier. Whether a measurement falls under legal metrology depends on national law; the international recommendation for dynamic measuring systems for liquids assesses the complete measuring system, not only the meter. A single meter approval does not cover the skid as a whole, including its heating and piping arrangement.
Design criteria
Parameter | Why it matters | Effect on selection |
Bitumen grade and modification | Viscosity, outgassing tendency and maximum temperature vary by grade | Meter type, gas handling, heating setpoint |
Operating temperature range | Sets sensor, seal and electronics limits | High-temperature version, remote electronics |
Viscosity and flow range | Affects pressure drop and low-flow accuracy | Meter size, pump head |
Commercial basis (mass, volume, weighbridge) | Changes calculation and record structure | Coriolis or PD meter, density data |
Heating medium | Drives jacket and tracing design | Thermal oil, steam or electric tracing |
Hazardous area classification | Affects electric heating and equipment protection | Ex-protected equipment and applicable standards |
Maintenance and verification approach | Zero checks and removal needs affect operations | Bypass, isolation valves, removable insulation |
What TLY Enerji brings
TLY Enerji supports bitumen metering projects by reviewing process data and helping define the right metering technology. Its portfolio includes Coriolis mass flow and density meters, temperature and pressure instruments and control valves. Depending on scope, TLY Enerji can supply this equipment, install and commission flow meters, integrate them with PLC or DCS systems and provide technical support after commissioning.
Data needed for a metering study
· Bitumen grades, polymer modification and the supplier's viscosity–temperature data
· Minimum, normal and maximum flow; temperature and pressure at the metering point
· Purpose of measurement: custody transfer, preset loading control or in-plant monitoring
· Commercial basis: mass, volume or comparison with a weighbridge
· Available heating medium and its conditions; electrical supply
· Hazardous area classification and signals to be sent to the control system
Related pages
· Heated metering skids for heavy oil and fuel oil: Cold-spot and insulation engineering on heated skids.
· Heated loading systems for bitumen: The full heating chain the meter sits in.
· Heavy oil metering skids: How viscosity drives technology choice.
· Bitumen truck unloading systems: Quantity and gas handling at the receiving point.
Frequently asked questions
Should bitumen be metered with a Coriolis or a PD meter?
Coriolis is the natural fit when the commercial quantity is mass and density monitoring is wanted, and heated jacket options are widely available. A PD meter can suit volume-based measurement where viscosity stays within a narrow band, provided pressure drop and calibration viscosity are addressed. The decision should be based on product data and the flow range.
Why is a meter jacket not enough on its own?
The jacket heats the sensor body, but unheated flanges, strainers and valves upstream and downstream will cool and collect deposits. The transmitter electronics also have temperature limits. The skid therefore has to be designed as a whole, combining the meter jacket, line heating and a suitable electronics mounting.
Under what conditions should the zero be set?
Common practice is to set or verify the zero at operating temperature with the meter full, flow stopped and free of gas. A zero set at ambient temperature may drift once the meter runs hot. The exact procedure should be confirmed against the meter manufacturer's instructions.
Why does polymer-modified bitumen need extra care?
Polymer-modified bitumen is more viscous, and a manufacturer case study reports that outgassing from the product caused noticeable meter deviations against the weighbridge. Gas handling functions, meter position and back-pressure design therefore become more critical for these grades.
Is bitumen metering subject to legal metrology?
That depends on national legislation and on how the measurement is used commercially. Where it applies, the assessment covers the complete measuring system, including heating and piping, not just the meter. The authority's requirements and the contractual measurement basis should be clarified at the start of the project.