Differential pressure measurement in cleanrooms
Differential pressure measurement in cleanrooms
Rooms for critical processes i.e. cleanrooms as well as mini environments demand precise environmental monitoring technology and methods in order to operate consistently within specifications. This is not just about meeting standards, but more importantly about the quality of your products e.g. pharmaceutical medicines, semiconductor chips, or manufacturing processes. Robust and highly accurate differential pressure instruments from Novasina address pressure measurement challenges and help with the smooth operation of your cleanroom facilities.
There are multiple standards that can be mentioned in connection with cleanrooms. While VDI 2083-19 addresses the tightness of containments, other standards state clear differential pressure difference requirements, like the DIN EN ISO 14644-3/4 cleanroom classification, VDI 2083 (3) or GMP Annex 1 of 5-20 or 5-15 Pa.
The primary approach to ensure the protection of people, products, and manufacturing environment is to create pressure cascades between rooms. This is intended to ensure that air always moves from a cleanroom to a non-controlled room. Additional techniques that are used to maintain cleanrooms include: point- and surface air extraction, clean air hoods, laminar flow workspaces, air curtain, filter fan units, mini environments, Restricted Access Barrier Systems (RABS), safety work benches for biology or similar, glove boxes, clean machines, isolators and other containments.
Measurement requirements in cleanrooms
According to DIN EN ISO 14644-3, the measurement requirements of minimal differential pressure must be between 0 to 50 Pa. To be able to successfully make this measurement, instruments with low measurement uncertainty are required for cleanrooms. Novasina provides a specific product line with an automatic mechanical zero point which makes it possible to measure very small pressure differences without being affected by the usual long term drift due to aging or mounting positions.
Due to the need to ensure that there always is an overpressure to ensure proper air flow, most instruments sold into cleanrooms are bi-directional, showing a range from e.g. -25 to +25Pa. With this measurement range, it can be documented for critical productions that room pressure did not drop below 0 Pa differential pressure between contamination-classes. In such cases, the low uncertainty provided by the mechanical auto-zero is critical.
Measurement methods in cleanrooms
Static method in cleanrooms
Dynamic method in cleanrooms
Cleanroom related filter and flow monitoring
The differential pressure drop measured across a filter of an air conditioning system allows conclusions about the degree of contamination and helps to set maintenance intervals. For filter monitoring a less accurate differential pressure instrument can be used as it is not necessary to determine such small differences.
Differential pressure can also be used for flow monitoring. The flow velocity due to a pressure drop over a restricting orifice or membrane diffuser can be calculated. A first calibration might be required, but after that, it is a good indicator for the flow velocity in m/s.
Our differential pressure measurement devices for applications in Cleanrooms
Find your contact person in your region
Our trained dealers can be found around the globe and will be happy to support you with your concerns.
Neuheimstrasse 12