Plastic pallet washing: methods, machines and hygiene
In briefA plastic pallet can be washed by hand, in a batch cabinet (20-30 pallets an hour according to one machine maker) or in an automatic tunnel (60-200 an hour). Stay within the material's limits: according to one pallet manufacturer's data, short peaks such as washing should not exceed about 110 °C for HDPE and 127 °C for PP.
Plastic pallet washing is possible because the material does not absorb water and does not splinter. To wash pallets properly, though, you need a method: a temperature the material can take, a suitable detergent, drying and records that will stand up to a HACCP inspection.
When you need to wash
Regulation (EC) 852/2004 requires containers used to transport food to be kept clean and, where necessary, designed to allow cleaning and disinfection. Equipment in contact with food must be cleaned and, where necessary, disinfected [1].
In practice, pallets are washed in three cases:
- food and pharmaceutical areas, where the HACCP plan or the quality system requires it;
- closed loops, where the pallet comes back dirty from the customer and goes out again;
- pallets entering cold stores or clean rooms, where outside dirt must not get in.
The rules on food contact and hygienic pallets are in the guide to hygienic and food pallets.
Three methods compared
| Method | Pallets per hour | Suits | Limits |
|---|---|---|---|
| By hand, pressure washer or manual cabinet | 20-30 in a cabinet [4] | few pallets, light dirt | variable result, hard to document |
| Batch machine | 20-30 [4] | dozens of pallets a day | manual loading |
| Automatic in-line tunnel | 60-100 [4], up to 100-200 in large systems [3] | hundreds of pallets a day | space, drainage, energy |
The values come from an American pallet washer maker, which points out that output varies a great deal with operator work, cycle time and the condition of the pallets [4].
A typical tunnel works in stages: hot water spray, spray and rinse, then a final rinse and drying [3]. Recirculating systems reuse the wash water and need topping up only for evaporation and for the water the pallets carry away [4].
Temperatures: what HDPE and PP can take
High temperature helps dissolve grease and residues, but the pallet has a limit. The figures from one pallet and container manufacturer [2]:
| Material | Continuous use | Short peaks, such as washing |
|---|---|---|
| HDPE | −50 °F to 170 °F, about −46/+77 °C | max 230 °F, about 110 °C |
| PP | −10 °F to 180 °F, about −23/+82 °C | max 260 °F, about 127 °C |
The Celsius conversions are ours. One Italian washing service sets the pressurised water temperature at up to 65 °C [5], well below those limits.
For a recycled plastic pallet these values are not guaranteed: ask the manufacturer for the limit of its material and write it into the purchase specification. If the pallet goes into a blast freezer straight after washing, it must be dry: see the guide to pallets for cold stores.
Detergents, rinsing, drying
One washing service describes detergents based on caustic alkalis, dispersants, anti-scale agents, rinse aids and chlorine donors, with a sanitising action; the rinse aid shortens drying time [5]. One machine maker points out that sanitisers and chemicals must be compatible with both the machine and the pallet material [4].
Drying uses blowers, air knives, long drip zones or heated stages [4]. Fans and blowers increase electricity consumption [4]. A pallet that stays wet in its cavities brings water into the warehouse and, in the cold, ice.
Wash in-house or buy the service
Before you choose a machine, the people who build them suggest starting from the utilities: water, power, drainage [4]. Then count the pallets and the dirt.
| Question | If the answer is yes |
|---|---|
| Do you wash more than a few dozen pallets a day, every day? | your own machine, batch or tunnel |
| Is the dirt light and are there few pallets? | pressure washer or cabinet, with a written procedure |
| Are you short of space, drainage or staff? | outside service |
| Do you need a washing certificate for each batch? | a service that issues one, or a machine that records its cycles |
An outside service can also inspect the pallets: some report breakages, defects and non-conformities on the pallets they wash and issue a washing certificate [5].
Documenting washing for HACCP
Regulation 852/2004 does not set a washing frequency for pallets [1]: your HACCP plan decides it. At an inspection you will be asked for proof that you wash as you have written. For this reason we suggest at least:
- a written procedure: detergent, concentration, temperature, times, rinsing, drying;
- a log for each batch: date, number of pallets, cycle used, operator;
- periodic checks on effectiveness, using the method set by your quality manager;
- rejection of damaged pallets, because cracks and worn surfaces hold dirt that washing does not reach. Repair, take-back and recycling are covered in used plastic pallets.
Pallets designed to wash well
The shape of the pallet matters as much as the machine. A closed, smooth deck has no gaps where dirt builds up. Rounded corners let the spray reach everywhere. Closed, welded runners leave no cavities where water can collect.
Among the flat pallets ROLL offers, the PPH1 is designed for washing: 800×1200, closed runners with welded bases, closed surfaces and no exposed cavities, 19 kg [6]. It is made of post-industrial recycled PP, so it is not suitable for direct food contact [6]: use it with packaged goods, in clean warehouses and in pharmaceutical logistics.
If you wash pallets from a closed loop, washing is one item in the cost per trip: you will find it in the calculation in the guide renting or buying plastic pallets.
Frequently asked questions
At what temperature should a plastic pallet be washed?
It depends on the material and the cycle. According to one pallet manufacturer, short peaks such as washing should not exceed 230 °F, about 110 °C, for HDPE and 260 °F, about 127 °C, for PP. One Italian washing service works with pressurised water up to 65 °C. For recycled pallets, ask the manufacturer for the limit.
How many pallets an hour can a machine wash?
According to the tables of an American pallet washer maker, a manual cabinet or batch machine washes 20-30 pallets an hour, an automatic in-line machine 60-100, and the largest automatic systems reach 100-200 pallets an hour. The real output depends on how dirty the pallets are, the cycle and how much manual work is needed.
Is a pressure washer enough to clean pallets?
For a few pallets with light dirt, yes, as long as you use a suitable detergent, rinse and let them dry. The limit is repeatability: every operator washes differently and the result is hard to document. Once you are washing dozens of pallets a day, or your HACCP plan requires a recorded cycle, a machine or an outside service makes more sense.
How often should a pallet be washed in a food area?
No European regulation sets a frequency. Regulation (EC) 852/2004 requires containers and equipment in contact with food to be cleaned and, where necessary, disinfected. Your HACCP plan sets the frequency based on the product, the risk of contamination and the pallet's route.
Which pallet is easiest to wash?
One with a closed, smooth deck, rounded corners, closed runners and no open cavities where water can collect. A pallet with an open grid deck or open cells holds dirt and water, washes more slowly and dries badly.
Sources
- Regulation (EC) No 852/2004 on the hygiene of foodstuffs, Annex II, Chapters IV and V
- ORBIS Corporation: Temperature ranges for plastic products (HDPE and PP)
- Cherry's Industrial Equipment: Manual vs automatic pallet washing (commercial source)
- Cherry's Industrial Equipment: Pallet Washer Guide (commercial source)
- CMP: plastic pallet and container washing (service)
- ROLL PPH1, H1 hygienic pallet 800×1200 with closed runners (data sheet)
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