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Atmosphere Controlled Warehouse

Controlled Atmosphere storage

The market price for fruit and vegetables is primarily determined by quality, supply and demand. But how do you maintain the best quality in your products until the most suitable moment? Simple: by opting for storage under Controlled Atmosphere (CA) conditions.

By using CA, the physiological processes in the stored product are slowed down, resulting in an extended storage life. The product is put into hibernation so to speak. The required conditions are achieved by creating and maintaining a special protective atmosphere.

Lowering the oxygen level slows respiration and reduces the metabolism of important nutrients. The aim is to keep the oxygen level as low as possible in order to preserve these nutrients – hence quality.

The remaining oxygen is converted into CO2, which in turn ensures that the respiration of fruit and vegetables is further slowed down. However, excess CO2 will damage your product and must therefore be removed.

Ethylene is produced by fruit and vegetables and stimulates the ripening process – hence the ageing process. In order to slow down these processes, it is necessary to remove this harmful ethylene gas from the air of the cold stores for some products.

Each product variety requires different conditions. Depending on factors such as climate, weather, soil conditions, growing conditions and the time of picking, the optimum conditions vary not only year by year, but also from one product to another and even from one variety to another. As experts in CA storage, we offer you tailored solutions and every opportunity to keep a close watch on your valuable produce.

These days, many different storage concepts are available: ULO, DCA, ILOS, DILOS, DCE, etc. Şen Grup can supply both the protocols and the required equipment for these concepts.


PSA nitrogen generator

By lowering the level of oxygen in the cold store, respiration is slowed down and the ‘metabolism’ of important nutrients in fruits and vegetables is reduced. The objective is to keep the oxygen level in a cold store as low as possible in order to maintain quality and delay the ageing process as much as possible.

The reduction of the oxygen level in a cold store can be accelerated using a PSA (Pressure Swing Adsorption) nitrogen generator. A PSA generates pure nitrogen from normal ambient air which will be used to expel the oxygen from the cold store.

The Şen Grup PSA nitrogen generator consists of two vessels fitted with extremely high-quality CMS (carbon molecular sieve). A CMS is capable of adsorbing oxygen molecules for a particular length of time. When saturation is reached, the system automatically switches to the other vessel by means of valves. The saturated vessel is prepared for the next cycle by depressurizing it, after which the adsorbed oxygen molecules are released and purged. Thanks to this simple principle, the reliability and lifespan of the PSA nitrogen generator is extremely high.

All our PSA nitrogen generators are provided with filters and automatic drains so no fluid or oil can reach the CMS.

Şen Grup offers different capacities of PSA nitrogen generators. The capacity is chosen/determined depending on the volume and number of the cold stores.

Specifications PSA nitrogen generators


CO2 adsorber

Fruit and vegetables ‘breathe’, a natural process in which oxygen is converted into CO2 (carbon dioxide). An increased CO2 level in a cold store ‘calms’ the fruit, but an excess will cause damage and must therefore be removed.

A CO2 adsorber, also known as a scrubber, removes carbon dioxide from cold stores, along with a small portion of the harmful ethylene present. The CO2 adsorber contains active carbon, which has the characteristic of adsorbing CO2 molecules (binding them to it). By efficiently transporting the air from the cold store, passing it over the active carbon and returning it to the cold store, the CO2 is effectively removed from the air in the store.

Besides a user-friendly control panel for setting the actions per cold store, the adsorber is equipped with an ‘adsorber lung’. This patented system guarantees absolute low oxygen operation which means that virtually no oxygen can enter the cold store (ideal for storage under ULO and/or DCA conditions).

A frequency-controlled ventilator reduces energy consumption to a minimum – an important benefit because an adsorber runs for the majority of the day. In addition, the diameter of the pipe is matched to the size of the ventilator so no heat can enter the cold store as a result of friction.

Every fruit and vegetable variety has its own CO2 production and maximum permitted CO2 value. For this reason, Şen Grup produces different capacities of adsorbers so that we can always supply a solution for your application.


Ethylene converter

Ethylene gas is produced by fruit and vegetables and accelerates the growth, development, ripening and ageing of the product. Some fruit varieties, for example kiwis, are extremely sensitive to ethylene. The Şen Grup ethylene converter quickly and easily removes this harmful ethylene gas. In this way, your products retain their ‘eternal youth’.

The ethylene converter consists of two columns, each with a heat storage medium, a catalyst, heating elements and one ventilator. In turns, cold store air is guided upwards and heated per column. The air then passes through the catalyst bed where the ethylene gas is broken down. Finally, the air flow passes through the second catalyst bed, where the remaining ethylene is broken down and the air cooled back down.

With the Şen Grup ethylene converter, an ethylene level of 1 ppb (0.0000001%) can be achieved without making use of chemicals. This makes the process extremely environmentally-friendly. Thanks to heat recovery and accurate control of the optimum temperature, the converter consumes minimal energy.


Measurement and control technology

Measuring is knowing! Without accurate measurement and the appropriate control of the equipment, all kinds of things can go wrong. Şen Grup has developed its own measurement and control system (ACS – Atmosphere Control Station) which can be used to control your cold storage facility fully automatic. You only need to set the required values and the system will measure, control and maintain your chosen atmosphere.

Quality and reliability at the heart of your system are extremely important! As such, the sensors approved by Şen Grup meet four important requirements; sustainability, stability, accuracy and response time.

ACS can easily be expanded with the addition of a cooling module that allows any type of cooling system to be managed. It controls the cooling valves, defrost valves and ventilators, based on target values which you can set yourself. Besides temperature, relative humidity can also be measured and regulated, as can the quantity of defrost water, if required. Thanks to this total concept, ACS is capable to control your entire cold storage facility.

The analysis system can be connected to a PC with BatNetWin Software. In this way settings can easily be changed and the measured data are stored automatically. The registered data can be graphically displayed and printed, making it possible to generate various reports and, for example, compare different periods.

Şen Grup also supplies portable measuring equipment for manual measurement of O2 and CO2 values.



Cold store protection

During a storage season, a cold storage facility is constantly exposed to changing conditions that can directly affect the atmospheric conditions inside. Şen Grup offers solutions for optimum protection and security.

Breather bag / Bufferlung; As a result of changing air pressure and the temperature fluctuations inside the cold store, the air volume is constantly subject to changes. In order to neutralize these variations, a breather bag is fitted onto the cold store. The bag stores the excess air of the cold store and if necessary (in case of low pressure) returns it to the store. This prevents ingress of oxygen-rich outside air into the cold store.

Overpressure / underpressure protection; Under extreme conditions, a breather bag only is not sufficient anymore. For this reason, cold stores must also be equipped with overpressure and underpressure safety valves which starts operating at an overpressure / underpressure of 10 mm water column. Without this safeguard, the ceiling and/or walls of the cold store can be severely damaged.

Aeration ventilator; Based on measurement, the aeration ventilator keeps the CO2 percentage low during the loading / cooling period and allows oxygen to enter the store in a controlled manner during CA storage.



In addition to the equipment, Şen Grup also supplies all the necessary accessories, such as:

  • Gas-tight flanges
  • Gas-tight doors
  • Special coating for the gas-tight finishing of corners and panel joints in a CA cold store
  • Gas-tight store connections
  • Compressed air supply
  • Compressed air conditioning
  • Water measurement
  • Humidification, ultrasound and compressed air
  • Filters
  • Emergency power supply
  • These are just a few of our many accessories. Please contact us for other accessories or tailored solutions.

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