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During the storage season a cold store is constantly subjected to changing circumstances which can directly affect the atmospheric conditions in your cold rooms.

Because of changing air pressures as a result from atmospheric changes and temperature differences (including cooling actions), the air volume in a cold room is continuously subjected to underpressure and overpressure. A flexible air buffer, also known as a ‘buffer lung’, is installed to compensate these small pressure differences. The excess air in the cold room is captured in it (at overpressure) and, if necessary (at underpressure), returned to the cold room. This prevents the undesired penetration of oxygen-rich air. Using a buffer lung with a sufficient capacity can compensate for a big part these pressure variations.

However, there are circumstances that the buffer lung is insufficient to relief the cold room from its under- or overpressure. When the cold room is not relieved of this excess pressure difference, the panels of a cold room are literally pushed out (in the case of overpressure), or sucked inside (during underpressure), resulting in a lot of damage. Cold rooms should be fitted with over- and underpressure valves to protect against excessive pressure differences. The Besseling pressure reliefs have a diameter of 160 mm, which means that more air can be transported compared to a 125 or 110 mm overpressure valve. In short: better protection.

To give you an idea of the difference:
Ø 160 mm has a surface of 201 cm²
Ø 125 mm has a surface of 123 cm²
Ø 110 mm has a surface of 96 cm²

This means that a Ø 110 mm pressure valve has less that half of the compensation capacity compared to a Ø 160 mm valve. And a Ø 125 mm only 61%.

The problem with, in particular under pressure, is that is occurs in a split second, and therefore the pressure reliefs should be sufficiently dimensioned to quickly relief the room from its excess pressure.