Start From the Right Number: Litres per Day Before Tank Size
The most common question we receive on detergent projects is "how much does a detergent production line cost?" — a question with no answer until two numbers are fixed: how many litres per day you intend to produce, and what products are in your range. A liquid detergent and liquid soap line is not a single machine but a system: a preparation vessel, a main mixing tank with a homogenising head, intermediate storage tanks, transfer pumps, a demineralised water unit, a filling machine, then capping, labelling and packing. Real capacity is set by the slowest link in that chain — and in detergent projects the bottleneck is usually not the mixer but the filler, or the time it takes to discharge and clean a batch.
The Formula for Sizing Your Mixing Tank
Use this formula to size the gross tank volume: gross volume in litres = (target daily output in litres ÷ number of batches achievable per day) ÷ a 0.80 fill factor.
Worked example: your target is 20,000 litres per day of dishwashing liquid. A full batch cycle (charging raw materials, mixing and homogenising, heating or cooling, drawing a QC sample, then discharging) takes about 90 minutes, and your effective shift is 16 hours. That yields roughly 10 batches per day once cleaning time between products is deducted. Batch size is therefore 2,000 litres, and gross tank volume is 2,000 ÷ 0.80 = 2,500 litres. That headspace is not wasted money: it absorbs the foam generated by sulphonic acid and sulphates during agitation, and without it you will lose part of every batch onto the floor.
The classic mistake here is buying a tank sized to the full daily output. An oversized tank mixes badly at partial loads because the impeller sits above the liquid level, it is harder to clean, and it forces you to produce a single product per day. Two or three batches per product per day is operationally better than one giant batch.
Choosing the Agitation System by Product
| Product type | Approximate viscosity | Suitable agitation |
|---|---|---|
| Glass cleaner and liquid disinfectants | Below 100 cP | Slow propeller agitator only |
| Dishwashing liquid | 1,000 to 3,000 cP | Anchor agitator with baffles |
| Concentrated laundry liquid | 2,000 to 5,000 cP | Anchor plus high-shear homogeniser |
| Cream soap and fabric softener | 5,000 to 15,000 cP | Wall-scraping anchor plus homogeniser |
| Gels and thick cleaners | Above 15,000 cP | Planetary mixer with lobe-pump discharge |
A high-shear homogeniser is not a luxury in emulsions and fabric softeners — it is what stops phase separation two weeks into shelf life. Ask explicitly for its rotational speed and kW rating, not just a line item confirming that one exists.
Matching the Filling Machine to Your Product
Size the filler like this: daily output in litres ÷ operating hours ÷ pack size = containers per hour. In our example: 20,000 ÷ 16 = 1,250 litres per hour, and with a 1-litre pack that means 1,250 containers per hour. Add a 20 percent safety margin and specify a machine rated at 1,500 containers per hour minimum.
- Low-viscosity products fill accurately and faster on flow-meter or gravity systems.
- Medium and high-viscosity products need volumetric piston fillers.
- Foaming products require diving nozzles that descend into the container and rise with the liquid level.
- Nozzle count drives speed: four heads cover roughly 1,000 containers per hour, eight heads double it.
The golden rule: do not buy the mixing tank first. Define your product range, their viscosities and pack sizes, then select the filling machine, then build tank volume and batch count around it.
Materials of Construction and Corrosion Resistance
This single point separates a line that runs for ten years from one that corrodes in its first. Stainless steel 304 suits neutral and ordinary alkaline detergents. Acidic products such as acid-based bathroom cleaners require 316L on every contact surface. The most critical special case is chlorine bleach (sodium hypochlorite): its line must never be built in stainless steel at all, but in polyethylene, polypropylene or lined materials, and it must be a fully separate line with its own pumps, tanks and nozzles. Running bleach through the same equipment as an acid line is a genuine safety hazard, not a shortcut.
Utilities Importers Routinely Overlook
- A demineralised water or RO unit: total dissolved solids must stay below 50 ppm and hardness below 5 ppm, otherwise the finished product turns cloudy and forms sediment.
- Jacket heating by steam or electric elements — the choice materially changes running cost.
- Clean, oil-free compressed air at 6 to 8 bar to drive valves and the filling machine.
- A clean-in-place system, which cuts product changeover from two hours to under thirty minutes.
- Chemically resistant flooring with correct drainage falls, because spillage in this sector is a daily event.
Common Mistakes When Importing a Detergent Line from China
- Writing only "tank capacity" into the contract without distinguishing net from gross volume.
- Ignoring cleaning time between products when counting daily batches, which cuts real output by 30 percent.
- Buying a filler for one product and discovering it cannot handle the viscosity of another item in the range.
- Failing to demand a trial run using your own formulation rather than the supplier's.
- Skipping CE marking and material-contact conformity reports, which stalls customs clearance and industrial licensing.
- Overlooking the product labelling and safety data sheets required in your market before the labeller is designed.
What to Demand Explicitly in the Quotation
- Net and gross volume of every tank, wall thickness, and the exact stainless grade.
- Agitator and homogeniser power in kW and their respective speeds in rpm.
- Filling output in containers per hour for a named pack size and viscosity, plus the permitted weight tolerance.
- Total electrical load and steam or electricity consumption per batch.
- A hall layout drawing showing charging platform height and cleaning access routes.
- A wear-parts list for one full year, especially chemically resistant seals and gaskets.
A detergent plant is among the fastest industrial projects to repay its capital when batch volume and filling capacity are calculated correctly from the outset — and among the most frustrating when equipment is bought before the product range is defined. If you are planning a liquid detergent line or expanding an existing one, contact our team for an accurate batch-size and filling-capacity calculation with verified technical specifications before you release any down payment.