Pass boxes devices may operate both in negative and in positive pressure without compromising the safety and cleanliness performances. The pressure pattern set up and operational mode, mostly depends on the lay-out of the clean room or to meet specific standard requirements. They operate as standard in negative pressure in comparison to the pressures of the surrounding environments generating that so called “well of pressure“.

Positive step of pressure: the inside pressure is higher in comparison to not clean side area and lower than clean side area.

Overpressure: the inside pressure is higher in comparison to not clean side and clean side areas.

Well of pressure: the inside pressure is lower in comparison to not clean side area and clean side area.