KENYA STANDARD        KS 2409 -6: 201 8 
ICS13.030.30; 13.340.30  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Health care wastes management 
commodities  
 
Part 6:  
 
Filtering face masks to protect against particles — 
Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
©KEBS 201 8  First Edition 201 8 
 
PUBLIC REVIEW DRAFT  KS 2409 -6: 201 8 
 
ii  © KEBS 201 8 — All rights reserved  NATIONAL WORKSHOP REPRESENTATION  
 
The fo llowing organizations were represented on the National Workshop Agreement Meeting.  
 
City Council of Nairobi  
Coast Provincial General Hospital  
Nursing Council of Kenya  
Kenya Medical Supplies Agency  
Kenyatta National Hospital  
Ministry of Medical Services  
Kenya Expanded Progrmme of Immunization  
Reprentative, Rural Health Facilities  
Ministry of Public Health and Sanitation  
Government Chemist 's Department  
Moi Teaching and Referral Hospital  
Path-Kenya  
Christian Health Association of Kenya  
Ministry of Public Health and Sanitation — Office of the Chief Public Health Officer  
Ministry of Medical Services — Office of the Chief Nursing Officer  
Ministry of Medical Services — Office of the Director of Medical Services  
Kenya Medical Scientific Technical Officers Ass ociation  
Kenya Medical Research Institute  
Kenya Bureau of Standards  — Secretariat  
 
 
 
 
 
 
REVISION OF KENYA STANDARDS  
 
In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions 
for improvements to published stand ards, addressed to the Managing Director, Kenya Bureau of Standards, 
are welcome.  
 
 
 
 
 
© Kenya Bureau of Standards, 201 8 
 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 12 of 2001  of the Laws of Kenya, copyr ight 
subs ists in all Kenya Standards and except as provided under Section 26 of this Act, no Kenya Standard produced by Kenya Bureau o f 
Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in  writing 
from the Managing Director.  
 KENYA STANDARD        KS 2409 -6: 201 8 
ICS 13.030.30; 13.340.30  
© KEBS 2 018 — All rights reserved   iii  
 
 
 
 
 
 
 
 
 
 
 
 
Health care wastes management commodities  
 
Part 6:  
 
Filtering face masks to protect against particles — 
Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA BUREAU OF STANDARDS (KEBS)  
 
Head Office:  P.O. Box 54974, Na irobi-00200, Tel.: (+254  020) 605490, 602350, Fax: (+254 020)  604031  
E-Mail: info@kebs.org,  Web:http://www.kebs.org   
 
Coast Region     Lake Region          Rift Valley Region  
P.O. Box 99376, Mombasa -80100   P.O. Box 2949, Kisumu -40100        P.O. Box 2138, Nakuru -20100  
Tel.: (+254  041) 229563, 230939/40  Tel.: (+254 057) 23549, 22396        Tel.: (+254 051) 210553, 210555  
Fax: (+254  041) 229448    Fax: (+254 057) 21814  
 KS 2409 -6: 201 8 
 
iv  © KEBS 201 8 — All rights reserved   
 
Foreword  
 
Foreword  
 
Kenya Bureau of Standards is a national standards bod y (NSB). The w ork of preparing Kenya  Standards is 
normally carried out through national  technical committees. Each member body interested in a subject for 
which a technical committee has been established has the right to be represented on that committee. 
National  organi zations, governmental and non -governmental, in liaison with KEBS , also take part in the 
work.  
Kenya  Standards are drafted in accordance with the rules given in the KS ISO/IEC  Directives, Part  2. 
The main task of technical committees is to prepare National  Standards. Draft Kenya  Standards adopted by 
the technical committees are circulated to the technical committee member s for ballo ting. Publication as a 
Kenya  Standard requires approval by at least 2/3 of the member s casting a vote.  
Attention is drawn to th e possibility that some of the elements of this document may be the subject of patent 
rights. KEBS  shall not be held responsible for identifying any or all such patent rights.  
This Kenya Standard  was prepared by Technical Committee KEBS /TC 164, Furniture . 
During the development of this National Workshop Agreement, reference was made to the following 
standards.  
 
BS EN 149: 2001: Respiratory protective devices – Filtering half masks to protect against particles – 
Requirements, testing, marking.  
 
This assistan ce is hereby acknowledged.  
 
 
 
 KENYA STANDARD        KS 2409 -6: 201 8 
ICS 13.030.30; 13.340.30  
© KEBS 2 018 — All rights reserved   v Introduction  
 
Protective masks are pieces of kit or equipment worn on the head and face to afford protection to the wearer, 
and today usually have these functions:  
 
a) Providing a supply of air or filtering the outside air.  
 
b) Protecting the face against flying objects or dangerous environments, while allowing vision.  
 
In Roman gladiatorial  tournaments masks were sometimes used. From archaeological evide nce it is clear 
that these were not only protective but also helped make the wearer appear more intimidating. In medieval  
Europe and in Japan soldiers and samurai  wore similarly ferocious -looking protective armour , extending to 
face-masks.  
 
In sport the protective mask will often have a secondary function to make  the wearer appear more 
impressive as a competitor.  
 
Before strong transparent materials such as polycarbonate  were invented, visors  to protect the face had to 
be opaque with small eyeslits, and were a sort of mask, as often in mediaeval suits of armour , and (for 
example) Old Norse  grímr  meant "mask or visor".  
 
Also known as respirators they are  device s designed to protect the wearer from inhaling harmful dusts , 
fumes, vapors, or gases . Respirators come in a wide range of types and sizes used by the military, private 
industry, and the public. Respirators range from cheaper, single -use, disposable masks  to reusable models 
with replaceable cartridges.  
There are two main categories: the air-purifying respirator , which forces contaminated air through a filtering 
element, and the air-supplied respirator , in which an alter nate supply of fresh air is delivered. Within each 
category, different techniques are employed to reduce or eliminate noxious airborne contents.  
  
KENYA STANDARD        KS 2409 -6: 201 8 
 
 
© KEBS 201 8 — All rights reserved   1  
Health care wastes management commodities  
 
Part 6:  
 
Filtering face masks to pprotect against particles — Specification  
 
 
1 Scope  
 
This Part 6 of this Kenya National Workshop Agreement  specifies the requirements for filtering half masks as 
respiratory protective devices to protect against particlles except for escape purposes.   
 
2 Definitions  
 
For the purposes o f this Workshop Agreement, the following definition shall apply:  
 
2.1 
face masks  
are filtering devices covering the nose and mouth and the chin and may have inhalation and/or exhalation 
valve(s). It consist s entierly or substantially of filter material or comprises a facepiece in which the main 
filter(s) form an insepaarable part of the device.  
 
3 Description  
 
Filtering f ace masks are intended to provide adequate sealing on the face of the wearer against the ambient 
atmosphere, when the skin is dry or moist  and when the head is moved.  
 
Air enters the particle filtering half mask and passes directly to the nose and mouth area of the facepiece or,  
via an inhalation valve(s) if fitted. The exhalation air flows through the filter material and/or an exhalation 
valve (if fitted) directly to the ambient atmosphere.  
 
These devices are designed to protect against both solid and liquid aerosols.  
 
 
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2  © KEBS 201 8 — All rights reserved  
 
 
 
Figure 1 — Typical half filtering face mask  
 
 
 
4 Classification  
 
Particle filtering half masks are classified accordin g to their filtering efficiency and their maximum total inward 
leakage. There are three classes of devices;  
 
FFP1, FFP2 and FFP3.  
 
The protection provided by an FFP1, or FFP3 – devices includes that provided by the device of lower class 
or classes.  
 
5 Desi gnation  
 
Particle filtering half masks meeting the reqirements of this National Workshop Agreement shall be 
designated in the following manner:  
 
Particle filtering half mask NWA XX, year of publication, class  
 
where,  
 
XX is the number of this NWA.  
 
6 Requi rements  
 
6.1 General  
 
In all tests, all test samples shall meet the requirements.  
 
6.2 Nominal values and tolerances  
 
Unless otherwise specified, the values stated in this National Workshop agreement are expressed as 
nominal values. Except for temperature limits, values which are not stated as maxima or minima shall be KS 2409 -6: 201 8 
 
© KEBS 201 8 — All rights reserved    3 subject to a tolerance of ± 5 %. Unless otherwise specified, the ambient temperature for testing shall be 
room temperature with the temperature limits being subject to an accuracy of ± 1 °C.  
 
6.3 Visual inspection  
 
The visual inspection shall also include the marking and the information supplied by the manufacturer.  
 
6.4 Material  
 
Face masks shall be made of materials that are suitable to withstand handling and wear over the period for 
which t he particle filtering half mask is designed to used. They shall shall not suffer mechanical failiure of the 
facepiece or straps or even particle filtering collapse on undergoing condition ing described in Annex A.  
 
6.5 Cleaning and disinfecting  
 
If the part icle filtering half mask is designed for more than a single shift (i.e. not designed for single use only), 
the materials used shall withstand the cleaning and disinfecting agents recommended by the manufacturer 
when tested in accordance with the method dec sribed in Annex B.  
 
6.6 Leakage  
 
6.6.1  Total inward leakage  
 
For particle filtering half masks fitted in accordance with the manufacturer’s information, at least 46 out of the 
50 individuaal exercise results (i.e. 10 subjects X 5 exercises) for total inwar d leakage shall be not greater 
than 
 
25 % for FFP1  
 
11 % for FFP2  
 
 2 %  for FFP3  
 
when tested in accorance to Annex C.  
 
6.6.2  Penetration of filter material  
 
The penetration of the filter of the particle filtering half mask shall meet the requirements in Table 1 when 
tested in accordance with the method described in Annex D.  
 
Table 1 — Penetration of filter material  
 
Classification  Maximum initial penetration of test aerosols  
 Sodium chloride test 95 l/min.  
% max. Paraffin oil test 95 l/min.  
% max. 
FFP1  
FFP2  
FFP3  20 
6 
1 20 
6 
1 
 
6.6.3   Flammability  
 
When tested in accordance with the method described in Annex E, the particle filtering half mask shall not 
burn  for more than 5 s after removal from the flame.  
 
6.6.4   Breathing resistance  
 
When tested in acc ordance to the method described in A nnex F, the valved and valveless particle filtering 
half masks shall meet the requirements of T able 2.  KS 2409 -6: 201 8 
 
4  © KEBS 201 8 — All rights reserved   
Table 2 — Breathing resisstance  
 
Classification  Maximum permitted resistance (mbar)  
Inhalation  Exhalation  
30 l/m in. 95 l/min.  160 l/min.  
FFP1  
FFP2  
FFP3  0.6 
0.7 
1.0 2.1 
2.4 
3.0 3.0 
3.0 
3.0 
 
6.6.5  Clogging  
 
6.6.5.1   General  
 
For single -use devices only, the clogging test shall be optional.  
 
Devices designed to be resistant to clogging, shown by a slow increase of b reathing resistance when loaded 
with dust, shall be subjected to the treatment described in Annex G.  
 
6.6.5.2   Breathing resistance for the valved particle filtering half masks  
 
After clogging the inhalation resistances shall not exceed  
 
a)  FFP1: 4 mbar  
 
b)  FFP2: 5 mbar  
 
c)  FFP3: 7 mbar  at 95 l/min continuous flow  
 
The exhalation resistance shall not exceed 3 mba r at 160 l/min continuous flow.  
 
6.6.5.3   Breathing resistance for valveless fitering half masks  
 
After clogging the inhalation and exhahaltion resistance shall not exceed  
 
a) FFP1: 3 mbar  
 
b) FFP2: 4 mbar  
 
c) FFP3: 5 mbar  at 95 l/min continuous flow  
 
7 Marking and packaging  
 
7.1 Marking  
 
The following information shall be indelibly and legibly marked on the package of each mask in English.  
 
a) The name, registered trademark and/or other means of identification of the manufacturer or supplier.  
 
b) Classification: FFP1, FFP2, FFP3.  
 
c)  Year of the end of shelf -life. 
 
d)  The sentence “see information supplied by the manufacturer”, at least in the o riginal language(s) of 
the country of destination, or by using the pictogram as shown in Figure 12 . 
 
e)  The manufacturer’s recommended conditions of storage (at least the temperature and humidity) or 
equivalent pictogram, as shown in Figure 12 . KS 2409 -6: 201 8 
 
© KEBS 201 8 — All rights reserved    5 f)  The pa ckaging of the particlle filtering half masks passing the dolomite clogging test sha ll additionally  
be marked with the letter “D”.  
 
7.1.2  Particle filtering half mask  
 
Particle filtering half masks complying with this standard shall be indelibly and legib ly marked with the 
following information:  
 
a)  the name and registered trade mar k of the manufacturer or supplier.  
 
b)  the number and year of publication of this NWA.  
 
c)  the symbols FFP1, FFP2 or FFP3 according to class.  
 
d)  if appropriate the letter “D” in accordance with the performance.  
 
7.1.3  Information to be supplied by the manufacturer  
 
7.1.3.1  Information supplied by the manufacturer shall accompany every smallest available package.  
 
7.1.3.2 The information suplied by the manufacturer shall be  at least in English.  
 
7.1.3.3  The information supplied by the manufacturer shall contain all information necessary for trained and 
qualified persons on : 
 
a)  appli caction/limitation ; 
 
b)  the meaning of any colour coding  checks prior to use ; 
 
d)  donning , fitting ; 
 
e)  use; 
 
f)  maintenance (e.g. cleaning, disinfecting), if applicable ; 
 
g)  storage ; 
 
h)  the meaning of any symbols/pictograms used  of the equipment ; 
 
i)  Warning of any problems likely to be encountered e.g. fit of particle filtering half ma sks (check prior 
to use), it is unlikely that the requirements for leakage will be achieved if facial hair passes under the 
face seal, etc . 
 
7.2 Packaging  
 
Face masks shall be packed in polythene packs individually  or in any suitable way that they are pro tected 
against mechanical damage and contamination.  
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© KEBS 201 8 — All rights reserved    17  
Annex A  
(normative)  
 
Materials used for construction  
 
A.1 Visual inspection  
 
The visual inspection is carried out where appropriate by the test house prior to labo ratory or practical 
performance tests.  
 
A.2  Conditioning  
 
A.2.1   Simulated wearing treatment  
 
Conditioning by simulated wearing treatment shall be carried out by the following process.  
 
A breathing machine is adjusted to 25 cycles/min and 2.0  L/stroke. Th e particle filtering half mask is mounted 
on a Sheffield dummy head. For testing, a saturator is incorporated in the exhalation line between the 
breathing machine and the dummy head, the saturator being set at a temperature in excess of 37 °C to allow 
for the cooling of the air before it reaches the mouth of the dummy head. The air shall be saturated at (37 ± 
2) °C at the mouth of the dummy head. In order to prevent excess water spilling out of the dummy’s mouth 
and contaminating the particle filtering half  mask the head shall be inclined so that the water runs away from 
the mouth and is collected in a trap.  
 
The breathing machine is brought into operation, the saturator switched on and the apparatus allowed to 
stabilize. The particle filtering half mask und er test shall then be mounted on the dummy head. During the 
test time at approximately 20 min intervals the particle filtering half mask shall be completely removed from 
the dummy head and refitted such that during the test period it is fitted ten times to  the dummy head.  
 
A.2.2   Temperature conditioning  
 
Expose the particle filtering half masks to the following thermal cycle:  
 
a)  for 24 h to a dry atmosphere of 70 °C; ± 3 °C;  
 
b)  for 24 h to a temperature of -30 °C;± 3 °C; and allow to return to room tem perature for at least 4 h 
between exposures and prior to subsequent testing.  
 
The conditioning shall be carried out in a manner which ensures that no thermal shock occurs.  
 
 
 
 KS 2409 -6: 201 8 
 
18  © KEBS 201 8 — All rights reserved   
Annex  B 
(normative)  
 
Cleaning and disinfecting  
 
B.1 General  
 
A total of 2 part icle filtering half masks shall be tested: both as received.  
 
All tests shall be carried out by two test subjects at ambient temperature and humidity shall be recorded.  
 
Prior to the test there shall be an examination to assure that the particle filtering half mask is in good working 
condition and that it can be used without hazard.  
 
Examination shall be done in accordance with Clause A.1.  
 
For the test, persons shall be selected who are familiar with using such or similar equipment.  
 
During the tests, the particle filtering half mask shall be subjectively assessed by the wearer and after the 
test, comments on the following shall be recorded:  
 
a)  head harness comfort  
 
b)  security of fastenings  
 
c)  field vision  
 
d)  any other comments reported by the weare r on request.  
 
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© KEBS 201 8 — All rights reserved    19  
Annex C  
(normative)  
 
Leakage  
 
C.1 Leakage  
 
C.1.1  General test procedure  
 
C.1.1.1  Total inward leakage  
 
A total of 10 test specimens shall be tested: 5 as received and 5 after temperature conditioning in 
accordance with A.2.2.  
 
The total i nward leakage shall be tested using sodium chloride aerosol.  
Prior to the test there shall be an examination to ensure that the particles filtering half mask is in good 
working condition and that it can be used without hazard.  
Examination shall be done in accordance with  Clause  A.1. 
 
For the test, persons shall be selected who are familiar with using such or similar equipment.  
A panel of ten clean -shaven persons (without beards or sideburns) shall be selected covering the spectrum 
of facial characteristics  of typical users (excluding significant abnormalities).  It is to be expected that 
exceptionally some persons cannot be satisfactorily fitted with a particle filtering half mask.  Such exceptional 
subjects shall not be used for testing particles filtering  half masks.  
 
In the test report the faces of the ten test subjects shall be described (for information only) by the four facial 
dimensions (in mm) illustrated in Figure 2.  
 
C.1.1.2  Test equipment  
 
The test atmosphere shall preferably enter the top of the enclosure through a flow distributor, and be 
directed downwards over the head of the test subject at a minimum flow rate of 0,12 m/s.  The concentration 
of the test agent inside the effective working volume shall be checked to be homogeneous.  The flow rat e 
should be measured close to the subject’s head.  
 
A level treadmill is required capable of working at 6 km/h.  
 
C.1.1.3  Test procedure  
 
Ask the test subjects to read the manufacture’s fitting information and if more than one size or particle 
filtering half  mask is manufactured, ask the test subject to select the size deemed by him to be the most 
appropriate, if necessary the test supervisor shall show the test subjects how to fit the particle filtering half 
mask correctly in accordance with the fitting info rmation.  
 
Inform the test subjects that if they wish to adjust the particle filtering half mask during the test they may do 
so.  However if this is done, repeat the relevant section of the test, having allowed the system to resettle.  
The test subjects shal l have no indication of the results as the test proceeds.  
 
After fitting the particle filtering half mask, ask each test subject ‘Does the mask fit? If the answer is ‘Yes’, 
continue the test.  If the answer is ‘No’, take the test subject off the panel, rep ort the fact and replace with 
another test subject.  
 
The test sequences shall be as follows:  
 
a) Ensure the test atmosphere is OFF.  
 KS 2409 -6: 201 8 
 
20  © KEBS 201 8 — All rights reserved  b) Place the test subject in the enclosure.  Connect up the facepiece sampling probe.  Have the test 
subject walk at 6 km/h for 2  min.  Measure the test agent concentration inside the particle filtering half 
mask to establish the background level.  
 
c) Obtain a stable reading.  
 
d) Turn the test atmosphere ON.  
 
e) The subject shall continue to walk for a further 2 min or until the test atmosph ere has stabilized.  
 
f) Whilst still walking, the subject shall perform the following exercises:  
 
1) walking for 2 min without head movement or talking.  
 
2) turning head from side to side (appx. 15 times), as if inspecting the walls of tunnel for 2 min.  
 
3) moving the head up and down (approx. 15 times), as if inspecting the roof and floor for 2 
min. 
 
4) reciting the alphabet or an agreed text out loud as if communicating with a colleague for 2 
min. 
 
5) walking for 2 min without head movement.  
 
g) Record  
 
1) enclosure concentration;  
 
2) the leakage over each exercise period.  
 
h) Turn off the test atmosphere and when the test agent has cleared from the enclosure remove the 
subject.  
 
After each test, replace the particle filtering half mask by a new sample.  
 
C.2 Method  
 
C.2.1  Principle  
 
The subject wearing the particle filtering half mask under test walks on a treadmill over which is an 
enclosure.  
 
Through this enclosure flows a constant concentration of NaCl aerosol.  The  air inside the particle filtering 
half m ask is sampled and analysed during the inhalation phase of the respiratory cycle to determine the 
NaCl content.  The sample is extracted by punching a hole in the particle filtering half mask and inserting a 
probe through which the sample is drawn.  The pr essure variation inside the particle filtering half mask is 
used to actuate a change -over valve so that inhaled air only is sampled.  A second probe is inserted for this 
purpose.  
 
C.2.2  Test equipment (see Figure 3)  
 
C.2.2.1  Aerosol generator  
 
The NaCl aer osol shall be generated from a 2 % solution of reagent grade NaCl in distilled water.  An 
atomizer equivalent to the type described should be used (see Figure 4).  This requires an air flow rate of 
100 l/min at a pressure of 7 bar.  The atomizer and its ho using shall be fitted into a duct through which a 
constant flow of air is maintained.  It may be necessary to heat or dehumidify the air in order to obtain 
complete drying of the aerosol particles.  KS 2409 -6: 201 8 
 
© KEBS 201 8 — All rights reserved    21 C.2.2.2  Test agent  
 
The mean NaCl concentration within the  enclosure shall  be 8 mg/m3 ± 4 mg/m3 and the variation throughout 
the effective working volume shall be not more than 10 %.  The particle size distribution shall be 0.02 µm to 2 
µm equivalent aerodynamic diameter with a mass median diameter of 0.6 µm.  
 
C.2.2.3  Flame photometer  
 
A flame photometer shall be used to me asure the concentration of NaCl  inside the particle filtering half mask.  
Essential performance characteristics for a suitable instrument are:  
 
a) It should be a flame photometer specifically d esigned for the direct analysis of NaCl aerosol;  
 
b) It should be capable of measuring concentrations of NaCl aerosol between 15 mg/m3 and 5 ng/m3; 
 
c) The total aerosol sample required by the photometer should not be greater than 15 1/min.  
 
d) The respons e time of the photometer, excluding the sampling system, should not be greater than 
500 ms;  
 
e) It is necessary to reduce the response to other elements, particularly carbon, the concentration of 
which will vary during the breathing cycle.  This will be ac hieved by ensuring that the band pass 
width of the interference filter is no greater than 3 nm and that all necessary side -band filters are 
included.  
 
C.2.2.4  Sample selector  
 
A system is required which will switch the sample to the photometer only during the inhalation phase of the 
respiratory cycle.  During the exhalation phase, clean air shall be fed to the photometer.  The essential 
elements of such a system are:  
 
a) An electrically operated valve with a response time of the order of 100 ms.  The valve should have 
the minimum possible dead space compatible with straight -through, unrestricted flow when open;  
 
b) A pressure sensor which is capable of detecting a minimum pressure change of approx 0.05 mbar 
and which can be connected to a probe inserted in t he cavity of the particle filtering half mask.  The 
sensor shall have an adjustable threshold and be capable of differential signaling when the threshold 
is crossed in either direction.  The sensor shall work reliably when subjected to the acceleration 
produced by the head movements of the subject.  
 
c) An interfacing system to actuate the valve in response to a signal from the pressure sensor;  
 
d) Timing device to record the proportion of the total respiratory cycle during which sampling took 
place.  
 
C.2.2. 5 Sampling pump  
 
The probe shall be fitted securely in an airtight manner to the particle filtering half mask as near as possible 
to the centre line of the particle filtering  half mask.  A multiple hole sampling probe is strongly 
recommended.  
 
Measure sha ll be taken to prevent the influence of condensation in the sampling probe on the measurement 
(by supplying dry air). Figure 5 shows a design that has been found suitable.  The probe is adjusted so that it 
just touches the wearer’s lips.  
 
Care shall be tak en to ensure that the probe does not disturb the normal fit or shape of the mask.  
 
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22  © KEBS 201 8 — All rights reserved  C.2.2.6  Sample pump  
 
If no pump is incorporated into the photometer, an adjustable flow pump is used to withdraw an air sample 
from the particle filtering half mask under t est.  This pump is so adjusted as to withdraw a constant flow of 1  
l/min from the sample probe.  Dependent on the type of photometer it may be necessary to dilute the sample 
with clean air.  
 
C.2.2.7  Sampling of enclosure concentration  
 
The enclosure aeros ol concentration is monitored during the tests using a separate sampling system, to 
avoid contamination of the particle filtering half mask sampling line.  It is preferable to use a separate flame 
photometer for this purpose.  
 
If a second photometer is not  available, sampling of the enclosure concentration using a separate sampling 
system and the same photometer may be made.  However, time will then be required to allow the 
photometer to return to a clean background.  
 
C.2.2.8  Pressure detection probe  
 
A sec ond probe is fitted near to the sample probe and is connected to the pressure sensor.  
 
C.2.3  Expression of results  
 
The leakage P shall be calculated from measurements made over the last 100 s of each of the exercise 
periods to avoid carry over of results from one exercise to the other.  
 
 
100 
 
where,  
C1 is the challenge concentration;  
 
C2 is the measurement mean concentration in the breathing zone of the test subject;  
 
C3 is the total duration of inhalation;  
 
tEX is the total duration of exhala tion. KS 2409 -6: 201 8 
 
© KEBS 201 8 — All rights reserved    23  
Annex D  
(normative)  
 
Penetration of filtering material  
 
The device shall be mounted in a leaktight manner on a suitable former and subjected to the filter 
penetration test, ensuring that components of the device that could affect filter penetration  values such as 
valves and harness attachment points are exposed to the challenge aerosol.  
 
The testing shall be in accordance to KS XX1. 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                                           
1 KS XX under development.  KS 2409 -6: 201 8 
 
24  © KEBS 201 8 — All rights reserved   
Annex E  
(normative)  
 
Flammability test 
 
E.1  A total of four particle filtering half masks shall be tes ted: two in the state as received and two after 
temperature conditioning in accordance with Annex A.  
 
E.2 Procedure  
 
The face piece is put on a metallic dummy head which is motorized such that it describes a horizontal circle 
with a linear speed, measured at the tip of the nose, of 60 mm/s ± 5 mm/s.  
 
The head is arranged to pass over a propane burner the position of which can be adjusted. By means of a 
suitable guage, the distance between the top of the burner, and the lowest part of the face piece (when 
positioned directly over the burner) shall be set to20 mm ± 2 mm.  
 
With the head away from the area adjacent to the burner, the propane gas is turned on, the pressure 
adjusted to between 0.2 bar and 0.3 bar and ignited. By means of a needle valve and fine ad justments to the 
supply pressure, the flame height shall be set to 40 mm ± 4 mm. This is measured with a suitable gauge. 
The temperature of the flame measured at a height of 20 mm ± 2 mm above the burner tip by means of a 1.5 
mm diameter mineral insulated thermocouple probe, shall be 800 °C  ± 50 °C.  
 
 
 
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© KEBS 201 8 — All rights reserved    25  
Annex F  
(normative)  
 
Breathing r esistance  
 
F.1  Test samples and fixture  
 
A total of 9 valveless filtering half masks shall be tested: three as received, three temperature conditioned, 
three after the tes t for simulated wearing.  
 
The particle filtering masks shall be fitted securely in a leak -tight manner but without deformation on the 
Sheffield dummy head.  
 
The flow rate at which the resistance is measured shall be corrected at 23 °C and 1 bar absolute.  
 
F.2  Exhalation resistance  
 
Seal the particle filtering half mask on the Sheffield dummy head. Measure the exhalation resistance at the 
opening for the mouth of the dummy head using adapter shown in figure 6 and a breathing machine adjusted 
to 25 cycles/mi n and 2.0 L/stroke or a continuous flow 160 L/min. Use a suitable pressure transducer.  
 
Measure the exhalation resistance with the dummy head successively place in 5 defined positions:  
 
- Facing directly ahead  
 
- Facing vertically upwards  
 
- Facing vertically do wnwards  
 
- Lying on the left side  
 
- Lying on the right side  
 
F.3  Inhalation resistance  
 
Test the inhalation resistance at 30 L/min and 95 L/min continuous flow.  
 
 
 
 
 KS 2409 -6: 201 8 
 
26  © KEBS 201 8 — All rights reserved  Annex  G 
(normative)  
 
Clogging t est 
G.1 Principle  
 
The test aerosols shall be dolomite. A to tal of 3 particle filtering half masks shall be tested: 1 as received and 
2 after temperature conditioning in accordance to Annex A.  
 
The test consist of subjecting the particle filtering half mask to a sinusoidal breathing simulating, whilst the 
sample is  surrounded by known concentration of dolomite dust in air. Following the exposure, the breathing 
resistance and the filter penetration of the sample particle filtering half mask are measured.  
 
G.2  Test equipment  
 
A scheme typical apparatus is given in Fi gure 10. The working area of the test chamber has a suggested 
square section of 650 mm X 650 mm.  
 
The breathing machine has a displacement of 2.0 L/stroke. The exhalation air shall pass a humidifier in the 
exhaled air circuit, such that the exhaled air tem perature, measured at the position of the sample particle 
filtering half mask is (37 ± 2) °C and 95 % R.H. minimum.  
 
G.3 Test conditions  
 
Dust: DRB 4/15 dolomite  
 
The size distribution of dolomite dust is given in Table G.1.  
 
Table G.1 — Size distribution of dolomite dust  
 
Size (equivalent 
spherical diameter)  
µm % Number particles 
oversize  Size (stokes diameter)  
µm % weight oversize  
0.7 100 1 99.5 
1 80 2 97.5 
2 30 3 95 
3 17 5 85 
5 7 8 70 
9 2 12 26 
12 1 18 1 
 
G.4  The particle size distribution of th e airborne dust at the working area of the dust chamber is given in 
Figure 11.  
 
G.5  Procedure  
 
Convey dust from the distributor to the dust chamber where it is dispersed into the air stream of 60 m3/h. 
 
Fit the sample particle filtering half mask in a lea ktight manner to the dummy head or a suitable filter holder 
located in the dust chamber. Connect the breathing machine and humidifier to the sample and operate for 
the specified testing time.  
 
The concentration of the dust in the test chamber may be measur ed by drawing air at 2 l/min through a 
sampling probe equipped with a pre -weighed, high efficiency filter (open face, diameter 37 mm) located near 
the test sample, as shown in Figure 10.  
 
Calculate the dust concentration from the weight of dust collected, the flow rate through the filter and the 
time of collection.