Accurate control of 02 with the addition of HEPA filtration
The Whitley H35 Workstation can be supplied with the option of HEPA filtration to provide levels of atmospheric cleanliness inside the workstation that exceed the requirements of ISO 14644 Class 3. With the unique Whitley Internal HEPA Filtration System, all the atmosphere passes through the filter hundreds of times an hour to ensure the chamber environment is cleaned quickly. DWS filters are located inside the workstation, which prevents the filter becoming saturated with moisture and rendered ineffective. Rather than use off-the-shelf filters, DWS has worked with one of the world's leading filter manufacturers to develop a filter specifically tailored to suit this workstation.
To house this option, the H35 must be fitted with a removable front to facilitate replacement of the HEPA filter but having a removable front is also useful for thorough cleaning and for the transfer of bulk samples and larger pieces of equipment for use in the workstation.
The performance criteria for every model of Whitley HEPA workstation are based on test parameters and particle count data published in ISO 14644-1:2015 Cleanrooms and associated controlled environments – Part 1: Classification of air cleanliness by particle concentration. This ISO standard is very broad and encompasses diverse types of controlled environment. In the case of Whitley HEPA workstations, our factory test includes the enumeration of airborne particles with lower size limits of 0.3, 0.5, 1.0 and 5.0 μm, using a specified calibrated particle counter. To pass the test, particle counts in the internal chamber atmosphere must fall to zero per cubic metre, in each of these size ranges, within 20 minutes after commissioning the workstation. In addition, each of these counts must fall to zero per m3 within 20 mins after a period of operator activity has occurred within the chamber and the unit has been returned to the “at rest” state. This workstation comfortably meets this requirement. A certificate will be provided with your Whitley HEPA Workstation.
We can also provide revalidation after a filter change. Don Whitley Scientific supplies detailed procedures for re-testing filter / fan performance and particle counts in a HEPA Workstation following filter and fan replacement. These tests may only be performed by personnel who have received training from DWS and who are sufficiently familiar with the Whitley Internal HEPA Filtration System.
In addition to the workstation's main HEPA filter, the Enhanced Biological Containment system can also be specified. This option provides additional safeguards in reducing the possibility of bacteria contained inside workstations being released via the main chamber exhaust valve and the airlock exhaust valve.