Consider one large acid-resistant tank when you need to receive a large batch that cannot be split and can schedule periods out of service. Two smaller tanks may make it easier to separate batches and handle them at different times. The deciding factor is the schedule for the complete system: the same total capacity does not provide the same availability for filling.
Start by mapping tank duties over time
Start with a day when deliveries and product collection put the greatest demand on storage. For each batch, record its volume, arrival time, holding period and earliest possible start of discharge. Add the time needed for emptying, cleaning and checking that the tank is ready. Mark batches that must not be combined. A tank may be empty yet still unavailable for the next delivery.
Using a dairy as an example, Tetra Pak explains that tank number and size depend on the schedule, product separation and time required for batch release. This is a useful starting point for a purchasing discussion, although the parameters must be established for your own process. Source: Designing a process line.
Compare options whose materials are suitable for the medium, temperature and cleaning. The scheduling approach below helps prepare a purchase; installation parameters and the feasibility of running operations simultaneously require assessment for the plant.
When should you consider one larger tank?
This option merits comparison when the stock forms a single batch approved for common storage, or the process requires a large delivery to enter one vessel. The buyer should establish whether the available emptying, cleaning and inspection window is sufficient before the next fill.
Specify the largest single delivery and required working capacity in the enquiry. Do not automatically equate working capacity with the nominal capacity in a listing. The permissible filling level must suit the construction and process.
Also consider the sole tank being out of service. Where would the scheduled delivery go if product collection were delayed? Could the plant postpone filling? These questions help determine whether greater capacity actually solves the problem.
When might two smaller tanks be a better fit?
Consider splitting capacity when batches have different release statuses, products must not mix, or the next delivery needs a separate space. This requires genuinely separate handling arrangements.
Purely hypothetical example: compare one tank with a working capacity of 20 m³ against two with 10 m³ each. Batch A is 8 m³ and batch B is also 8 m³; they must not mix. Assume suitable separate transfer arrangements and the following schedule:
| Time | Tank holding batch A | Space for batch B or the next delivery |
|---|---|---|
| 08:00 | Batch A is already in the tank, awaiting release | The second tank in the two-tank option remains empty and ready |
| 10:00 | A still occupies the tank | B arrives; it can enter the second tank if the complete transfer route is confirmed ready |
| 12:00 | A is released; discharge can begin | B still occupies the second tank |
| 13:00 | The first tank is still being prepared for the next batch | No tank is available for a third, separate batch |
| 14:00 | Assumed completion of emptying, cleaning and readiness checks for the first tank | The next fill can be scheduled once readiness is confirmed |
An undivided tank cannot receive B at 10:00 without mixing it with A, despite having sufficient total capacity. Two tanks solve that conflict, but do not provide an available tank at 13:00. In this example, the decisive factor is how long each unit remains occupied, rather than litres alone.
The times and volumes only illustrate the method. They do not specify cleaning times or the performance of Agrotex tanks. If emptying or preparation takes longer, the assumed availability at 14:00 must move accordingly.
Check the opposite case too: a single batch is 15 m³ and must not be split. Neither tank with a working capacity of 10 m³ can receive it. Provided the other requirements are met, the larger single unit is then a better fit.
Two tanks do not guarantee operation during cleaning
For a plan where one tank operates while the other is cleaned, review product and cleaning-fluid routes and their separation with the designer. A shared pump, pipe or other component may restrict the independence of the tanks. Confirm the availability of utilities and personnel during the planned period too.
The cleaning plan covers the entire circuit in use, not just the tank interior. In the CIP circuits described by Tetra Pak, all components being cleaned must be available for cleaning at the same time. Assess a second tank purchase alongside the ability to separate its circuit from the operating part of the installation. Source: Cleaning of dairy equipment.
Treat breakdown backup in the same way: ask which duty the remaining tank could take over and for how long. Do not assume full continuity in the investment case without checking the complete system.
Compare both options on one purchasing sheet
| Question | What to record for each option |
|---|---|
| Can it receive the largest batch? | Required and confirmed working capacity of an individual tank |
| Can it keep batches separate? | Which batches need separation and where they will be directed |
| When will it be available? | Filling, holding, discharge, cleaning and inspection |
| What happens during downtime? | Duties that can continue and their limitations |
| What does commissioning cost? | Purchase, modifications, transport, positioning and connections |
| Will it fit in the plant? | Dimensions, operating access and access for bringing equipment in |
Use separate columns to compare the cost of one tank with the cost of a pair. For the two-tank option, include both units and the necessary connections, valves, instrumentation and controls. Check logistics and operating space for both options. Use actual quotation scopes; do not assume the cost of a pair equals twice the price of one unit.
When buying used equipment, assess each unit separately. The same catalogue capacity does not establish identical equipment or readiness for service. Different capacities for different duties may also be worth considering if they fit the schedule. First eliminate options that cannot handle the required batches, then compare the costs of those that remain.
How do you move from comparison to specific offers?
Select units for further assessment from the acid-resistant tank category. One catalogue example is offer 1047 — a 50.7 m³ tank with a coil. It is a starting point for enquiries about individual units, not a ready-selected pair or confirmation of working capacity for your process.
If the duty is to balance flow between stages, the article on buffer tanks in a production plant may also help.
Call +48 508 914 182 or email krzysztof@zbiornikiagrotex.pl. Provide offer numbers, the largest batch volume, product separation requirements and available space. Ask for the information needed to compare a single-tank option with a two-tank option.
