When a food plant receives liquid product by tanker, two questions must be settled before the product reaches a silo: is it acceptable, and how much was delivered? Quality is confirmed from the delivery documents, product temperature and a representative sample. Quantity comes from weighing or from a meter in the reception line, and with milk a meter is only reliable once entrained air has been removed. Both results go into one reception record, together with the destination tank and confirmation that the line was cleaned afterward, so that any later quality issue can be traced back to a specific tanker and silo.
How product is driven out of the tanker, suction design, gas elimination and meter-to-tank reconciliation are covered on the truck unloading systems page. Here the focus is milk, juice concentrate, liquid sugar and edible oil.
Decide first, then unload
At a fuel terminal, product usually goes straight to the receiving tank once the paperwork checks out. In food reception, one unsuitable load can compromise an entire silo, so reception is typically sequenced as follows:
1. Check the delivery note, certificate of analysis, latest cleaning document and, if used, the inbound weighing ticket.
2. Measure product temperature against the acceptance range for that product.
3. Have authorized site staff take a representative sample and run rapid acceptance tests.
4. If all is in order, release the load and assign the receiving tank or silo.
5. Unload, measure the quantity and clean the reception line.
Unloading into the wrong tank is a quality risk in its own right, more likely when intake points are not marked and locked or the driver has no document stating the destination tank. The destination tank valve can be interlocked so it opens only after that load has been released; which steps become hard interlocks is set by the site food safety procedure.
Sampling and temperature: the first quality signals
Milk reception may include taste and smell, bacteria count, somatic cell count and fat and protein tests, and the results can affect supplier payment. For other food liquids, tests depend on the product and the buyer specification. The sample must represent the load and must not contaminate it. Sampling from the vehicle should be minimized and left to authorized site staff. A hygienic sampling point in the reception line allows closed-system sampling, provided it is included in the cleaning circuit.
Temperature is both a safety and a quality parameter for many food liquids. EU food hygiene legislation requires vehicles, where necessary, to keep foodstuffs at appropriate temperatures and allow monitoring. In milk reception the temperature is monitored, and milk is usually chilled below +4 °C in a plate heat exchanger on its way to the raw milk silos, so the reception temperature becomes a field in the reception record. Hygienic sensor mounting is covered on the sanitary metering skids page.
Quantity: weigh it or meter it?
Received quantity is established either by weight or by a flow meter in the reception line. Weighing means a weighbridge reading before and after unloading, or a weighing tank on load cells.
Ways to establish received quantity
Method | What it gives you | What to watch |
Weighbridge (in and out) | Mass of product unloaded | Vehicle condition must not change between the two weighings |
Weighing tank on load cells | Mass of product received into the tank | Hygienic tank design; piping connections must not load the cells |
Flow meter in the reception line | Volume or mass; flow rate and total | Air elimination, unit matching the contract, meter in the cleaning circuit |
If the contract is in kilograms and the meter measures volume, a conversion is needed. In legal metrology this is the role of a conversion device, which uses temperature and density to convert volume at metering conditions into volume at base conditions or mass. A Coriolis mass flow meter measures mass directly; a magnetic flow meter measures volume in conductive products. Fix the invoicing quantity before design starts.
Air elimination: what throws off milk measurement
Air drawn in with the liquid is counted by the meter as product, so milk reception lines place an air eliminator ahead of the meter. Typically the reception pump starts when milk in the air eliminator reaches a preset level and stops when the level drops, so the meter sees only de-aerated product. The milk also passes a strainer.
Where the measurement is used to pay the supplier, legal metrology applies. The EU Measuring Instruments Directive lists milk measuring systems separately, and OIML R 117-1 defines a distinct system type for milk, beer and foaming potable liquids. The air eliminator also needs a hygienic review so it does not become a pocket that cleaning solution cannot reach.
Unloading method and product path
Food tankers are usually unloaded by pump. Stopping the pump stops the flow at once, but the tanker must be vented at the top because a road tank is not built to withstand vacuum, and vent air that contacts the product may need filtering. Pressure unloading avoids a pump to clean and keeps the compressor out of product contact, but gas blows through into the receiving tank at the end, and the tanker must be depressurized before leaving. Gas quality for food service depends on the product and buyer specification.
Viscous products such as liquid sugar or juice concentrate raise suction-line friction and cavitation risk at the impeller inlet; a short, generously sized line from tanker to pump also shortens unloading. Hygienic pump selection and line drainage are covered on the hygienic transfer systems page.
After unloading: cleaning the line and the tanker
Between deliveries, the reception line is a chain of product-contact surfaces: hose or arm, strainer, air eliminator, pump, meter and piping up to the heat exchanger. EU food hygiene legislation requires such equipment to be effectively cleaned and, where necessary, disinfected. The design defines how this chain joins the clean-in-place (CIP) circuit, whether enough cleaning flow passes the air eliminator and meter, and how the hose is cleaned. Milk tankers are cleaned after each collection round; if this is done at the receiving plant, tanker and line cleaning are separate, separately recorded cycles.
Design criteria
Parameter | Why it matters in design | Effect on selection |
Product type and tendency to entrain air | Air and foam distort meter readings | Need for an air eliminator, pump control, meter type |
Reception temperature and chilling | Temperature is both an acceptance criterion and a quality parameter | Temperature measurement point, in-line chilling, record field |
Time needed for acceptance tests | The tanker waits, or product goes to a holding tank, until results are in | Sampling point, holding tank, release interlock |
Invoicing unit | Mass and volume call for different measurement chains | Weighbridge, weighing tank, Coriolis or magnetic meter; need for conversion |
Cleaning arrangement | The reception line, and possibly the tanker, must be cleaned | CIP connections, cleaning flow, separate cycle records |
Working with TLY Enerji
Depending on project scope, TLY Enerji can support selection of the reception line measurement technology; supply of meters, temperature and level instruments, valves and pumps; release steps and pump control in a PLC-based system; data acquisition and reporting; and installation, testing and commissioning. Responsibility for hygienic design documentation, food-contact declarations of compliance and legal metrology procedures is defined in the technical specification.
What we need to assess your reception point
· Products received, with typical temperatures and viscosities
· Tankers per day, compartments per tanker and target unloading time
· Acceptance tests and how long results take
· Invoicing unit (mass or volume) and whether the measurement is used for payment
· Number of destination silos and the in-line chilling arrangement
· Existing CIP system and whether tankers are cleaned on site
Related pages
· Sanitary metering skids: Meter principle and hygienic mounting.
· CIP / SIP compatible systems: Cleaning-cycle compatibility of the line and air eliminator.
· Hygienic transfer systems: Pump, valves and line drainage.
· Truck unloading systems: Unloading methods and reconciliation for any liquid.
· Food-grade truck loading systems: Loading the same product at the shipping plant.
Food tanker unloading FAQ
Can unloading start before the acceptance tests are complete?
It depends on the site food safety procedure and test duration. With quick results, the tanker waits and product goes to the silo only after release. With longer tests, the load can go to a holding tank kept apart from the main silos and be transferred after release. In both cases, interlocking the destination valve to the release keeps unreleased product out of main stock.
Why does the air eliminator control the pump in a milk reception line?
Air enters at hook-up and as the tanker runs empty. If the pump runs only while the air eliminator level is above a preset point, the meter receives only de-aerated milk. Otherwise the meter counts air as product and the received quantity reads high. The air eliminator itself must also be hygienic and cleanable.
Should the quantity be measured as mass or volume?
Use the unit in the contract and for payment. A weighbridge, a weighing tank and a Coriolis meter all give mass directly. A volumetric meter needs temperature and density data to convert to mass or base-condition volume. This choice defines the instruments in the measurement chain and how it is verified, so make it at the start of design.
Should the sample come from the tanker or from the reception line?
Sampling from the vehicle is minimized and, where unavoidable, done by authorized site staff. A hygienic sampling point in the reception line allows closed-system sampling, but only once unloading has begun, which is why some plants combine a pre-unloading sample with one taken during discharge.