| Berlin, 11/05/2000 Sender:
Dr-Ing H.Peters
Dr-Ing Martin Möritz
Institut für Lufthygiene, Berlin
This survey describes the approximate results of tests about the efficiency
of Expansion Electronic HI-TECH NATURE SYSTEM in the reduction of micro-organisms
(bacteria and yeasts) in the air.
Tests
The tested environmental air has been loaded with a defined concentration of artificial
yeasts and bacteria, before the ventilation unit. An ATM 225 generator by the firm
Leschke, Frankfurt-Oder, and a K13 generator by the firm Klimatechnik, Berlin, have
been employed for the simultaneous emission of aerosols. The test germs used have been Micrococcus
luteus on behalf of bacteria and Rhodotorula rubra on behalf of yeasts. The
numbers of germs in the air has been calculated simultaneously before and after the
electrostatic filtration unit, after each emitter and at the air exit of the delivery
opening (after the revitalization stage). To accomplish the test the HI-TECH
equipment has been connected to a ventilation unit of variable volumetric capacity by the
firm HANSA (HKG-5 model). A 6-level Andersen - Kaskaden - ImpaktorenI has been used
for the measuring. Each withdrawal lasted 5 minutes with an air capacity of 28,3
l/min. The Petri (d=85 mm) catchment plates have been used with agar of Trypton-Soya (M.
luteus) and agar of malt extract (R.rubra) respectively.
(...)
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Results
The following tables synthesise the results of the tests. In particular, they carry the
reductions of the germ concentration through HI-TECH system:
| M.luteus Red. (%) |
| 2,6 m/s |
99,77
% |
| 4,6 m/s |
99,67 % |
|
|
| R.Rubra Red. (%) |
| 2,6 m/s |
99,96
% |
| 4,6 m/s |
99,94 % |
The results of the tests show that the HI-TECH system is able to eliminate the
aero-scattered bacteria (M.luteus) and yeasts (R.rubra) from the air with an efficiency
superior of 99,7%. The efficiency produced with the electro-filters tested utterly
exceed the efficiency of traditional fine filters (F5-F9).
As a consequence of these results, the electro-filters tested belong into the HEPA*
classification.
*
The DIN 1946, 4th part (3/99), came into force for airing plants in hospital environments,
obliges the first-class airing plants (e.g.: operating theatres) to have a three-step air
filtration process through the following filters: G4 class (pre-filter), F7 class (II
step) and a high-efficiency HEPA filter (III step), a maximum concentration of
10KBE/mc in the delivery air. After the second filtration step, the aeroscattered-germ
concentration do not have to exceed 1000 germs in the correct operation conditions of
the air conditioning and airing plant.
Considering
as a reference basis for the efficiency of the HI-TECH system the minimum threshold of
99,44% (obtained through the after electro-filter tests), it can be said that this value
is included in the limits established by DIN 1946. But this conclusion limits the results
refereed to the approximate test and to the tests by sample. An always valid statement for
the use of the HI-TECH system in hospital environments is possible only after tests of a
consistent statistical sample.
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