The machines, equipped with powerful fans and durable Hepa filters, achieve high efficiency ratios. The motors can withstand pressure drags, and thus the useful life of the filters increases without the machine losing the required negative pressure. Air handling pipes can be joined by means of various adapters.

When the exhaust air can not be led out and the greatest possible separation rate is desired (e.g. hospitals, fine electronics), all Lifa machines can be equipped with Hepa filters. It is also possible to use two separate Hepa filter boxes which are joined via a Y branch neck to another negative air machine, so that a larger amount of air is obtained in one machine. This method has been used in dustfree renovations in connection with asbestos demolitions, etc.

Lifa Air and Finnish Technical Research Centre VTT have developed in cooperation the method by which each unit is tested and quaranteed that there are no leakages.

Principle of the measurement system

The developed test setting measures the whole HEPA unit system so that the exact measurement of the airflow rate, filtration efficiency and detection of possible leaks can be done within a few minutes. The aerosol generator produces DESH particles at a constant rate. The aerosol concentrations upstream and downstream of the air handling unit are measured with an optical particle counter (Met One). The test system is capable of measuring air handling units which have air flow rates from 400 to 5000 m3/h. The new test method is routinely used in a company making asbestos removal work (Hesasbest).