How to choose
an olive oil tank.

Why stainless steel

Stainless steel is the benchmark material for storing olive oil: it releases no odours or flavours, resists corrosion and can be cleaned thoroughly. For our tanks we use AISI 304L or AISI 316L. 316L contains molybdenum and has better corrosion resistance; the choice depends on the product and the use. It is also possible to build only the top shell ring and the roof in 316L and the rest in 304L.

The conical bottom

Freshly extracted oil keeps settling sediment at the bottom of the tank. A conical bottom channels it to the lowest point, where the drain valve is: the sediment can be separated from the clear oil and the tank empties completely, with no product left standing. This is why we recommend a conical bottom for olive oil, while a flat bottom sloping towards the front remains a common choice for other products.

Oxygen: nitrogen blanketing

The enemies of olive oil are oxygen, light and heat. The steel keeps the light out; against oxygen the answer is nitrogen blanketing: in the empty part of the tank the air is replaced with nitrogen, an inert gas, so that the oil is in contact with as little oxygen as possible. A nitrogen generator produces the gas on site and supplies it to the tanks. How nitrogen blanketing works.

Filling and emptying

The oil can be filled from the top or from the bottom. When filling from the top, the product must not cascade down: we make it flow down the tank wall. The valves on our olive oil tanks have DIN connections on both sides. In a turnkey plant, a pumping station fills and empties the tanks through stainless steel piping.

Temperature

Olive oil suffers from both heat and cold: below about 10 °C it turns cloudy and the waxes settle out. To keep it at the right temperature, the tank can have jackets in which water, or water and glycol, circulates, and it can be insulated. With a heat-pump chiller the same system can cool or heat. The jackets are positioned differently depending on whether they are needed for cooling only, heating only or both: this depends on where the storage room is, and we decide it at the design stage.

Cleaning

The tank must be washed between seasons. With a removable spray ball under the top and a CIP tank that heats water and caustic soda, cleaning takes place in a closed loop, without anyone entering the tank. After rinsing, the tank is left to drain and dry with the manway open: no water must remain before the oil goes back in.

Capacity, dimensions and finishes

In our workshop we build tanks from 1,000 litres up to the largest size that can be transported; beyond that, we build them directly on site, so far up to 15 m in diameter and 20 m high. Diameter and height are also chosen to suit the available space, starting from the height of the room. Capacity should be based on the real volumes: a tank kept full can be protected with nitrogen, a half-full one cannot. Several smaller tanks are often the better choice. Finishes (2B, Scotch-Brite, satin, Fioretto, mirror-polished) are chosen separately for the inside and the outside.