Truck loading and unloading systems move product between storage and road tankers safely and in measured quantities, and they are built from the same set of blocks: a pump; a metering chain of strainer, air/vapor eliminator, meter and control valve; a batch controller that runs each load; loading arms and couplers at the tanker; safety permissives such as grounding, overfill prevention and emergency shutdown; a vapor connection; and an automation layer over all of it. Choosing the right solution comes down to five decisions: transfer direction, loading method, number of bays and arms, level of automation, and the commercial purpose of the measurement.
This page lays out those decisions independent of the product handled and points to the solution page that covers each one. Product-specific requirements are covered on the industry pages.
Scope of supply: skid, bay or terminal?
Very different scopes can be quoted under the same name, so the first decision is the level at which the work is defined. What matters is not only what falls inside the boundary but who owns the interfaces across it: signals, pressure conditions, power supply and data.
· Skid level: The metering and control unit is supplied on its own; pumps, loading arms and storage stay outside. Pump start signals and permissives must be defined as interfaces. The truck loading systems and custody transfer loading skid pages go into detail.
· Bay level: Loading arms, bay equipment and the vapor connection are added to the skid, and the loading method is chosen at this level.
· Terminal level: Multiple bays, storage and tank gauging, product receipt, the terminal automation system, vapor processing and site traffic are handled together; capacity planning and automation belong here.
Five decisions that map the solution
· Transfer direction: Loading pushes product from a pressurized line into the tanker. Unloading puts the suction side, pump feed, and air or vapor entrainment as the tanker empties at the center of the design.
· Loading method: Bottom loading is done at ground level, lets several compartments fill at once through standard adaptors, and brings vapor collection and overfill sensor connections to the same interface. Top loading goes through the tanker's hatch, and the arm outlet must stay near the tank bottom to avoid splash loading.
· Bays, arms and products: The number of bays, the arms per bay and the products each arm can deliver are independent dimensions; capacity and product segregation are set by planning all three together.
· Level of automation: Options range from a single bay run by a local batch controller to a terminal automation system (TAS) with driver identification, order matching and enterprise resource planning (ERP) integration.
· Purpose of measurement: Process metering for stock control and custody transfer measurement for sales are designed to different levels of rigor. Where legal metrology applies, separate error limits are set for the complete measuring system and for the meter, so one device approval never covers the whole system.
How the product changes the design
The building blocks stay the same, but the product drives the details. Volatile fuels such as gasoline put vapor collection and emissions control up front. LPG, stored as a liquid under pressure, needs back-pressure control to keep product liquid in the meter, plus a vapor return line. LNG brings cryogenic temperatures, line cool-down and material selection. With chemicals, material compatibility, sealing and preventing cross-contamination come first. The industry pages cover these differences in depth.
TLY Enerji's role in loading and unloading projects
For fuel and LNG tanker loading and unloading facilities, TLY Enerji provides system design, product supply, engineering, installation, commissioning and maintenance. For LPG tanker loading and unloading stations, it provides design, supply and engineering support. Supply of instruments, valves and pumps, along with automation and control systems for loading and unloading operations, can be part of this scope. Whether a project is handled at skid, bay or wider system level, and where the scope of supply ends, is agreed on the basis of the technical specification.
What we need for a first technical discussion
· Products to be transferred and their key properties
· Transfer direction: loading, unloading or both
· Target number of trucks per day and expected peak hours
· Tanker fleet type and loading method in use
· Whether this is a new facility or an upgrade of existing bays
· Purpose of measurement and existing automation or ERP systems
Solutions and industries in this category
· Truck loading systems: Process flow and components of a single loading point.
· Truck unloading systems: Receiving product from tankers into storage and verifying the quantity.
· Top loading systems: Safety, vapor and operator ergonomics when loading through the hatch.
· Bottom loading systems: Matching adaptor, vapor return and overfill prevention interfaces.
· Multi-bay and multi-arm truck loading terminals: Planning capacity, layout and product segregation.
· Automated truck loading terminals: Automation layers from order verification to the bill of lading.
· Custody transfer truck loading skids: Verifying quantity and keeping records when product is sold.
· Fuel terminals: Loading and vapor requirements specific to gasoline, diesel and jet fuel.
· LPG terminals: Loading, metering and safety needs of a liquid held under pressure.
· LNG terminals: Specific requirements of cryogenic transfer and metering.
· Chemical and petrochemical terminals: Transfer systems built around material compatibility and segregation.
Quick answers
Can loading and unloading share the same bay?
Yes. Some batch controllers also handle unloading, and metering skids can be designed for both directions. Unloading, however, changes pump suction conditions, the role of the air eliminator and the flow direction. For two-way use, meter and valve suitability in both directions, product segregation and bay traffic need to be assessed together; busy terminals often assign the two operations to separate bays.
Can one terminal offer both top and bottom loading?
It can, and this is common at terminals serving different products or different tanker fleets. Bays are usually dedicated to one method, because vapor collection, overfill prevention and operator platform requirements differ between the two. In some jurisdictions, bottom loading with vapor collection is mandatory for volatile products such as gasoline, so the decision is made together with the product and local regulations.
Does every loading point need custody transfer metering?
No. A custody transfer measuring system is needed where product is sold on the basis of the meter reading or where the measurement falls under legal metrology. For internal transfers, or where the sale is measured at another point, process metering may be sufficient. The decision depends on the contract structure, national regulations and the point where ownership changes hands.