Publicité
Les langues disponibles
Les langues disponibles
Protection limits
The duration of the filters depends on the class and the use: humidity and temperature of inspired air, work rate, concentrations
and combinations of the toxic in the environment. For these reasons it is impossible to predict the duration of use if the above
information are not known. To evaluate the dangerousness of toxic, gas or particle, the Threshold Limit Value (TLV) is used. TLV
represents the maximum concentration of a substance that a man can be exposed to, for a shift of eight hours, without
consequences or damage.
Gas filters
Gas filter of higher class can be used (with the same mask) in environments where a lower-class filter is required, in the below table
are listed the toxic concentration (expressed as Multiple of the limit value TLV) that shouldn't be exceeded for each type of mask.
Type of Mask
Half mask or quarter mask
Full face mask or mouthpiece devices
Filter class
1
2
3
* The old denomination of the gas concentration is shown in brackets.
According to the present production standards, as a rule the following classes of filters correspond to:
Class 1 Gas filter
Class 2 Gas filter
Class 3 Gas filter
Filters for NO must be used only once. CO filters must be used only once for the maximum time specified by the filter class (20, 60
or 180 minutes) and anyway they must kept in sealed package until use.
Protection capacity and test conditions of type A, B, E and K gas filter according to EN 14387:04/A1:2008 standard
Type
and class
A1
Cyclohexane (C
B1
Hydrogen sulphide(H
Hydrogen cyanide(HCN)
E1
Sulphur dioxide(SO
K1
Ammonia(NH
A2
Cyclohexane (C
B2
Hydrogen sulphide(H
Hydrogen cyanide(HCN)
E2
Sulphur dioxide(SO
K2
Ammonia(NH
A3
Cyclohexane (C
Multiple of the limit value
TLV
30
400
Filter Capacity
Low
Medium
High
Test gas
H
)
6
12
Chlorine(Cl
)
2
S)
2
)
2
)
3
H
)
6
12
Chlorine(Cl
)
2
S)
2
)
2
)
3
H
)
6
12
It must not be used in case of gas concentration higher than
those fixed for class 1, 2 or 3 gas filters (see related table)
small filter equipped with special screw-in or with snap-on connector;
normal filter or filter equipped with screw-in connector complying with EN
148/1;
filter to be connected to the mask by means of a corrugated hose.
Concentration of test gas
(PPM)
1000
1000
1000
1000
1000
1000
5000
5000
5000
5000
5000
5000
8000
14
Observations - limitations
Maximum allowed gas concentration *
3
1000 ml/m
= (0,1 vol.% = 1000 ppm)
3
5000 ml/m
= (0,5 vol.% = 5000 ppm)
3
10000 ml/m
= (1,0 vol.% = 10000 ppm)
Minimum breakthrough time in test
conditions (min)
70
20
40
25
20
50
35
20
40
25
20
40
65
Publicité
