KENYA STANDARD  KS 2168 -2:2020  
ICS ##.### 
2nd Edition  
 
 © KEBS  2020   
 Masonry cement  
Part 2:  
Test method  
 
 
 
 
 
 
TECHNICAL COMMITTEE REPRESENTATION  
The following organizations were represented on the Technical Committee:  
1. Apex Systems Consulting Group Limited  
2. Aurecon Kenya  
3. Bamburi Cement  
4. Blackberry House Ltd  
5. Drychem Kenya Solutions Ltd.  
6. East African Portland Cement  Company Plc  
7. Institution of Engineers of Kenya  
8. Institute of Quantity Surveyors of Kenya  
9. Institution of Engineers Of Kenya  
10. Jiangxi Youse  
11. Kenya Builders & Concrete Co Ltd  
12. Ketraco  
13. KTDA Power Company Limited  
14. Moi University  
15. Mombasa Cement Ltd.  
16. Multimedia University of Kenya  
17. Nairobi Western Bypass Project  
18. Roads Division, State Department of Infrastructure, Ministry of Transport, Infrastructure, Housing, 
Urban Development and Public Works  
19. Royal Automation Systems  
20. Technical University of Kenya  
21. Technical Unive rsity of Mombasa  
22. University of Nairobi  
23. 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 standards, addressed to the Managing Director, Kenya Bureau of Standards, are 
welcome.  
© Kenya Bureau of Standards, 2020  
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 130 of 2001 of  the Laws of Kenya, copyright subsists 
in all K enya Standards and except as provided under Section 25 of this Act, no Kenya Standard produced by Kenya Bureau of Standards 
may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing f rom the  
Managing Director.   Masonry cement  
Part 2:  
Test method  
Kenya Bureau of Standards,  Popo Road, Off Mombasa Road,  
P.O. Box 54974 - 00200,  Nairobi, Kenya  
 +254 020 6948000, + 254 722202137, + 254 734600471  
 info@kebs.org  
 @KEBS_ke  
 kenya bureau of standards (kebs)  
  
Foreword  
This Kenya Standard was prepared by the Cement and Lime  Technical Committee under the guidance of the 
Standards Projects Committee, and it is in accordance with the procedures of the Kenya Bureau of Standards  
This second edition cancels and replaces the first edition which has been technically revised  
KS 2168 consists of the following parts, under the general title Introductory element — Main element:  
 Part 1: Composition, Specifications and conformity criteria  
 Part 2: Test method  
During the preparation of this standard, reference was made to the following documents(s):  
EN 413 Masonry cement Part 2: Test method  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 KENYA STANDARD  KS 2168 -2:2020  
 
Masonry cement  
Part 2:  
Test methods  
1. Scope  
  
This Standard describes reference and alternative test methods to be used when testing masonry cements to 
assess their conformity to KS 2168 -1. It gives the tests on fresh mortar for consistence, water retention and air 
content.  
 
In the event of a dispute , only the reference methods are used.  
 
2.   Normative references  
 
The following documents, in whole or in part, are normatively referenced in this document and are indispensable 
for its application. For dated references, only the edition cited applies. For undated references, the latest edition 
of the referenced document (including any amendments) applies.  
 
KS EAS 148 -1, Methods of testing cement - Part 1: Determination of strength  
 
EN 196 -3:2005 + A1:2008, Methods of testing cement - Part 3: Determination of setting times and soundness  
 
EN 459 -2:2010, Building lime - Part 2: Test methods  
 
 
3.   General requirements for testing  
 
3.1. Laboratory  
 
Unless specifically stated to the contrary, all the tests described in this document shall be carried out in a 
laboratory where the air temperature is maintained at (20 ± 2) °C and the relative humidity at not less than 50 
%.  
 
3.2. Manufacturing tolerances for  test equipment  
 
3.2.1.       Dimensions  
 
Figures indicating the specified requirements for apparatus used in the tests described in this document shall 
include essential dimensions for which manufacturing tolerances are given. Unless otherwise stated, tolerance  
class m according to ISO 2768 -1should be applied.  
  
NOTE Other dimensions are given for guidance.  
 
3.2.2.        Mass  
 
Specified masses shall have manufacturing tolerances within ± 1 % of the mass unless otherwise stated.  
 
3.3. Tolerances for test equipment in use  
 
Tolerances applying to apparatus, which has been subjected to wear in use shall not exceed twice the 
corresponding manufacturing tolerance unless alternative requirements are specified.  
 
3.4.  Number of tests  
 
Where the test is one of a series subject to statistical control, determination of each property by a single test 
shall be the minimum required. Where the test is not part of a series subject to statistical control, two tests shall 
be performed to determin e each property.   
 
4.  Determination of setting time  
 
4.1.  General  
 
The setting time is determined by observing the penetration of a needle into a cement paste of standard 
consistence until it reaches a specified value.  
 
The setting time is determined in accor dance with either method A (4.2) or method B (4.3). Method B is the 
reference method.  
 
4.2.  Method A  
 
The setting time is determined in accordance with EN 196 -3:2005 + A1:2008.  
 
NOTE Experience has shown that the method specified in KS EAS 148 –3, in which the specimens are tested under water, is not suitable 
for some masonry cements which have low clinker contents.  
 
4.3.  Method B  
 
4.3.1.   Test principle  
 
The equipment used and the specimen preparation procedures are as described in EN 196 -3:2005 + A1:2008 
but with the additional requirement for a room or a humidity cabinet of maintained at (20 ± 1) °C and not less 
than 90 % relative humidity.  
 
4.3.2.   Initial setting time procedure  
 
Calibrate the Vicat apparatus with the needle, attached in advance of the test, by lowerin g the needle to rest on 
the base -plate to be used and adjusting the pointer to read zero on the scale.  
 
Raise the needle to the stand -by position.  
 
Fill a Vicat mould in accordance with EN 196 -3:2005 + A1:2008, 5.2.2 with paste of standard consistence mi xed 
in accordance with EN 196 -3:2005 + A1:2008, 5.2.1  
 
Place the filled mould and base -plate in the room or humidity cabinet and after a suitable time, position the 
mould and base -plate under the needle of the Vicat apparatus. Lower the needle gently unti l it is in contact with 
the paste. Pause in that position for between 1 s and 2 s in order to avoid initial velocity or forced acceleration 
of the moving parts. Then release the moving parts quickly and allow the needle to penetrate vertically into the 
paste. Read the scale when penetration has ceased, or 30 s after the release of the needle, whichever is the 
earlier.  
 
Record the scale reading, which indicates the distance between the end of the needle and the base -plate, 
together with the time from zero. Repeat the penetration on the same specimen at conveniently spaced 
positions, not less than 8 mm from the rim of the mould or 5mm from each other and at least 10 mm from the 
last penetration position, at conveniently spaced intervals of time, e.g. at 10 mi n intervals. Between penetrations 
keep the specimen in a room or humidity cabinet. Clean the Vicat needle immediately after each penetration. 
Retain the specimen if determination of the final setting time is to be made.  
 
  
4.3.3.   Report – initial setting time  
 
Report the elapsed time measured from zero to the time at which the distance between the needle and the 
base -plate is (6 ± 3) mm as the initial setting time of the cement to the nearest 5 min. If the initial setting time 
exceeds 6h determine the final set ting time.  
 
4.3.4.   Final setting time procedure  
 
Invert the filled mould and follow the procedure described in EN 196 -3:2005 + A1:2008: 6.3 with the specimen 
held in the room or humidity cabinet at controlled humidity rather than under water.  
 
 
 
 4.3.5.   Report – final setting time  
 
Report the elapsed time measured from zero to that at which the needle first penetrates only 0,5 mm into the 
specimen as the final setting time of the cement, to the nearest 15 min. 4.3.6 Repeatability and reproducibility 
The standard deviation of repeatability is 4 min for initial setting time and 7 min for final setting time. The standard 
deviation of reproducibility is 20 min for initial setting time and 24 min for final setting time. These precision data 
take into account uncertainty of measurement.  
 
5.  Preparation of standard mortar  
 
5.1.  Principle  
 
The properties of fresh mortar made with masonry cement are assessed on standard mortar prepared in 
accordance with KS EAS 148 -1, but with the water content necessary for the stand ard consistence.  
 
The consistence is measured using the plunger apparatus (see 5.2) as the reference method to achieve the 
required value of penetration.  
 
A flow table test (see 5.3) is allowed as an alternative to the plunger test but it is important that the flow table 
spread equivalent to the required value of penetration is established, using the same type of masonry cement 
as that which shall be tested.   
 
5.2. Consistence of fresh mortar by plunger apparatus (reference method)  
 
5.2.1.   Apparatus  
 
The mixer and ancillary equipment shall be as described in KS EAS 148 -1.  
 
The plunger apparatus shown in Figure 1 shall conform to the dimensions specified. The shape of  the baseplate 
(1) shall enable the mortar container (8) to be placed centrally below the plunger (7).  
 
The plunger shall have a hemispherical lower end, be resistant to corrosion and not attacked by mortar. The 
total mass of the rod (6) and plunger (7) s hall be (90 ± 2) g. A release mechanism (5) holds the measuring rod 
in its initial position so that the lower end of the plunger is (100 ± 0.5) mm above the mortar surface prior to 
commencing the test (the initial position in 5.2.2).  
 
The tamper (see Figu re 2) shall consist of a round rod made of impermeable material with sheet metal protection 
and shall weigh (250 ± 15) g.  
 
5.2.2.   Procedure  
 
Prepare the mortar according to the procedure described in KS EAS 148 -1 except that the water content shall 
be that determined to give the consistence required.  
 
Before the start of each test wipe the plunger with a damp cloth.  
 
Fill the container in two layers immediately after completing the mixing procedure. Compact each layer with 10 
light strokes of the tamper.  
 
Strike off the excess mortar, within 1 min of completion of mixing, by a gentle sawing action using the 
straighted ge held at an angle of about 45 degrees. Then at a slightly flatter angle smooth the surface in a single 
direction in the reverse direction. After placing the container on the base -plate, release the plunger from its initial 
position (150 ± 15) s after the  completion of mixing and determine the value of penetration into the mortar by 
reading the scale.  
 
A value of penetration of (35 ± 3) mm is required for the mortar to be of standard consistence. If the mortar does 
not achieve the standard consistence req uired then mix a new batch of mortar using a different quantity of water. 
Repeat the test on new batches of mortar until the value of penetration of (35 ± 3) mm is obtained in two 
consecutive tests.  
 
Record the mass of water required in grams to obtain st andard consistence and the value of penetration in 
millimetres.  
 
 
 
 5.2.3.   Reproducibility  
 
The reproducibility which can be expected, expressed as the standard deviation of the results of the penetration 
test obtained by different, well -experienced, laborator ies is 3.0 mm.  
 
5.3. Consistence of fresh mortar by flow table (alternative method)  
 
5.3.1.   Method  
 
NOTE The flow table method has been retained as an alternative to the plunger method (reference method) as it is still widely  used.  
 
5.3.2.   Apparatus  
 
5.3.2.1.   Flow table, as described in EN 459 -2:2010, 6.8.2.1.2.  
 
5.3.3.  Calibration  
 
Calibrate the flow table, using the same type of masonry cement as that to be tested, against the plunger used 
for the consistence test described in 5.2. Carry out a minimum of three pa irs of tests at different water contents 
in order to establish the spread range on the flow table which is equivalent to a (35 ± 3) mm value of penetration 
using the plunger apparatus. Then adopt this spread in order to achieve the defined level of consist ence 
required. The relationship between the values using the flow table and the plunger apparatus shall be 
established for all products and updated at least once every 12 months.  
 
It is recommended to establish a relationship between flow and penetration over the range 30mm to 40mm 
penetration.  
 
5.3.4.   Procedure  
 
Before the start of each test, ensure that the plate and inner surface of the mould are clean and dry.  
 
If the flow table has not been used during the hour prior to the test, the empty table shall be  jolted several times. 
There shall be neither fluid nor dirt between the bearing (6) and the boss (8) (see EN 459 -2:2010, Figure 16).  
 
In order to determine the flow diameter, place the mould in the centre of the clean, dry surface of the flow table 
(5.3.2.1). Fill it with two layers of mortar (prepared just before in accordance with 5.2.2) during which operation 
the mould with the mounted hopper shall be held firmly onto the plate with one hand in such a way that its edge 
coincides with the circle engrave d on the plate. Spread each layer of mortar by tamping it lightly 10 times with 
the tamper (Figure 2) so that the mould is filled uniformly.  
 
Remove the hopper without delay, and strike off the excess mortar, within 1 min of completion of mixing, by a 
gentle sawing action using the straightedge held at an angle of about 45 degrees. Then at a slightly flatter angle 
smooth the surface in a single direction in the reverse direction. Clean the flow table and remove any water in 
the proximity of the mould. Afte r 10 s to 15 s have elapsed from the time the mortar has been struck off, lift the 
mould slowly and vertically from the plate (150 ± 15) s after the completion of mixing. Spread the mortar by 
jolting the plate 15 times at one jolt per second. Measure the d iameter of the pat with a calliper in two directions 
at right angles to one another. Report the mean value of these measurements to 1 mm as the flow.  
 
A value of flow corresponding to a plunger penetration of (35 ± 3) mm is required for the mortar to be of  standard 
consistence. If the mortar does not achieve the standard consistence required then mix a new batch of mortar 
using a different quantity of water. Repeat the test on new batches of mortar until the required value of flow is 
obtained.  
 
Record the mass of water required in grams to obtain standard consistence and the value of flow in millimetres.  
 
6.  Determination of water retention  
 
6.1.  Principle  
 
The fresh mortar, of standard consistence, is subjected to a suction treatment under defined conditions using 
filter paper as a substrate. The water retention of the mortar is the mass of water retained in the mortar after the 
suction treatment and is expressed as a percentage by mass of its original water content.  
 
 
 
 6.2.  Preparation  
 
Having completed the consistence test described in 5.2 or 5.3, remix the mortar remaining in the mixing bowl 
on low speed for 15 s and then carry out the water retention test. Should the time interval between the 
commencement of mixing and the start of the  suction period of the water retention test exceed 10 min, then a 
fresh batch of mortar shall be prepared.  
 
 
Dimensions and tolerances in millimetres  
 
Key  
1 base -plate  
2 support  
3 holder  
 
The use of apparatus in which the height of the holder above the base -plate can be varied, is acceptable, 
provided that for tests to this standard the height shall be set to the value specified in Figure 1  
 
4 guide bushes  
5 release mechanism  
6 aluminium  measuring rod (scale with 1 mm graduations)  
7 plunger  
8 container (with drip protection)  
Figure 1 — Plunger apparatus for measuring consistence  
 
Dimensions and tolerances in millimetres  
 
Figure 2 — Tamper  
 
6.3. Apparatus  
 
6.3.1.  Rigid mould of (100 ± 1) mm internal diameter and (25 ± 1) mm internal depth.  
 
6.3.2.  Metal straightedge, as described in KS EAS 148 -1.  
 
6.3.3.  Mass, 2 kg.  
 
6.3.4.   Rigid plate, non -porous (110 ± 5) mm diameter, (5 ± 1) mm thick.  
 
6.3.5.   Cotton gauze or non -woven tissue1) two circles (110 ± 1) mm diameter or two squares of (110 ± 1) 
mm side, of nominal area weight 20 to 90 g/m2 dry gauze or tissue, each piece having a nominal thickness of 
0.06mm to 0.19mm and nominal permeability to air o f 1 000 to 2 500 l/m2s.  
 
6.3.6.   Balance, with a capacity of at least 2 kg and capable of weighing to 0.1 g.  
 
6.3.7.   Filter paper, eight circles, (110 ± 1) mm diameter of 180 g/m2 to 200 g/m2 dry paper, each circle 
having a nominal thickness of 0.40 mm and having a n ominal particle retention size of 6 μm. Discard all used 
filter papers.  
 
6.3.8.   Palette knife, with a blade 150 mm to 200 mm long and 20 mm to 30 mm wide.  
 
6.4. Procedure  
 
Weigh the empty and dry mould (6.3.1) to the nearest 0.1 g (u). Weigh the eight circles of unused filter paper to 
the nearest 0.1 g (v).  
 
Fill the mould with the mortar in about 10 increments using the end of the palette knife until the mortar is slightly  
above the edge of the mould. Strike off the excess mortar by a gentle sawing action using the straightedge held 
at an angle of about 45°. Then at a slightly flatter angle smooth the surface in a single direction in the reverse 
direction.  
 
Weigh the mould  and its contents to the nearest 0.1 g (w). Cover the surface of the mortar with the two pieces 
of cotton gauze and place the eight circles of filter paper on top of the gauze. Place the non -porous plate on top 
of the filter papers, invert the mould on to a flat surface and place the 2 kg mass on the inverted base of the 
mould.  
 
 After (300 ± 5) s remove the 2 kg mass, re -invert the assembly, remove the rigid non -porous plate, filter papers 
and the cotton gauze and weigh the filter papers to the nearest 0.1  g (x).  
 
Calculate the mass of mortar involved in the test as (w – u), then the mass of water present (z),  
 
𝑧=𝑦(𝑤−𝑢)
1350+450+𝑦 
where:  
u is the mass of the empty mould, in grams;  
w is the mass of the mould and its contents, in grams;  
y is the mass o f the water used to produce mortar having a penetration of (35 ± 3) mm, in grams.  
 
The mass of water taken up by the filter papers is given by (x – v).  
 
Calculate the water retention as a percentage by mass of the total water from:  
 
𝑅=[𝑧−(𝑥−𝑣)]100
𝑧 
 
where:  
v is the mass of the eight filter papers before absorption, in grams;  
x is the mass of the eight filter papers after absorption, in grams;  
z is the mass of water present in the mortar before absorption, in grams.  
 
Where the test is not part of a series subject to statistical control and two individual test results differ by more 
than twice the standard deviation of repeatability (1 %), repeat the test and take the mean of the two closest 
test results. Report the wat er retention value, which is expressed to the mean of the two closest test results. 
Report the water retention value, which is expressed to the nearest 1 %.  
 
6.5.  Repeatability and reproducibility  
 
The standard deviation of repeatability is 0.5 %.  
 
The stan dard deviation of reproducibility is 3.1 %.  
 
These precision data take into account uncertainty of measurement.  
 
7. Determination of air content  
 
7.1. General  
 
Two methods for determining the air content are included in this document. The pressure method (7.2) is the 
reference method and the alcohol method is the alternative method (7.3). Other methods may also be used 
provided that prior to use they have been sh own to give similar results to the reference method.  
 
This test shall be carried out on a fresh batch of mortar of standard consistence prepared as in 5.2.2.  
 
7.2.  Pressure method (reference method)  
 
7.2.1.        Principle  
 
The air content of the fresh mortar is determined from the reduction in volume when a pressure is applied.  
 
7.2.2.        Apparatus  
 
The test apparatus (see Figure 3) consists of a metal cylinder (sample container) with a capacity of (0.75 ± 0.05) 
L or (1.00 ± 0 .05) l1). The sample container (1) and the cover (2) are sealed airtight together by means of clamps 
(3). The valve (7) is provided to enable filling with water and venting of air. The air is compressed by means of 
a pump (4). The pressure gauge (8) has a scale to measure the air content with divisions not greater than 0.5 
%.  
 
7.2.3.       Calibration  
 
Calibration shall be carried out, in addition to the manufacturer's instructions, in accordance with the following 
procedure:  
 
a) Measure and record the total wei ght of the air content meter on a dry basis.  
 b) Fill the air content meter 100 % with water, close the valve and take a calibration reading at zero air 
content.  
c) Measure and record the total weight of the air content meter as filled in b).  
d) Calculate the difference between c) and a), d,  
                                                   
1 It may be necessary when using the 1.00 l container to increase the size of the batch of mortar.  e) Take calibration readings at 5 approximately equally spaced values within an approximate range of 
5% to 25% air content using the calculated difference, d.  
 
The calibration test values obtained shall be used in con junction with the pressure gauge readings to derive a 
relationship that can be used to correct the values when read from the pressure gauge (see 7.2.4).  
 
7.2.4.  Procedure  
 
Record the weight of the empty sample container (a).  
 
Immediately after mixing has been completed, place the mortar into the sample container in two approximately 
equal layers. The final layer of mortar shall slightly overfill the sample container. To remove air bubbles lightly 
touch each layer using 10 strok es of the tamper (Figure 2), evenly distributed over the surface of the mortar. 
Strike off the mortar level with the top edge of the container as described in 6.4.  
 
Wipe the edge of the container clean with a moist cloth or with a sponge.  
 
Record the wei ght of the filled container (b)  
 
The air content shall be determined between 5 and 10 min after the test mortar has been mixed.  
 
Place the cover (2) onto the container. Seal the cover and the container airtight together by closing the clamps 
(3).  
 
Allow both the valves (5) and (7) to remain open.  
 
Use a squeeze bottle to squirt water into the valve (7) until all air still remaining in the meter has been evacuated 
through the overflow valve (5) [the water which flows out through the valve (5) shall be wit hout air bubbles].  
 
Operate the air pump until the pressure indicator has reached the initial prescribed level.  
 
Should the pressure fall slightly after a few seconds, increase the pressure by pumping again until the pressure 
indicator has again reached the mark. If the indicator goes past the mark then this shall be corrected by partially 
opening correction valve (6) until the pressure indicator has returned exactly to the mark.  
 
Shut both valves (5) and (7). Open the correction valve (6) until the pres sure equalization has been achieved. 
Tap lightly on the gauge until the indicator comes to rest and read the air content of the mortar as indicated. 
Correct this reading using the calibration relationship derived in 7.2.3.  
 
After testing, open both valves (5) and (7) slowly to relieve the pressure in the sample container (1) and then 
repeat the test.  
 
Where the test is not part of a series subject to statistical control and two individual test results differ by more 
than twice the standard deviation of rep eatability (0,5 %), repeat the test and take the mean of the two closest 
test results.  
 
The plastic density of the mortar is calculated from the difference between (a) and (b) divided by the nominal 
volume of the container (7.2.2).  
 
Report the plastic density, which is expressed to the nearest 10 kg/m3.  
 
Report the air content value, which is expressed to the nearest 0.5 %.  
 
Variations to this procedure may be found between apparatus supplied by different manufacturers. However, 
the manufacturers’ ins tructions have to be followed to obtain a calibration  
 
7.2.5.  Repeatability and reproducibility  
 
The standard deviation of repeatability is 0.5 %.  
 
The standard deviation of reproducibility is 1.0 %.  
 
These precision data take into account uncertainty of measu rement.  
 
 
 
  7.3. Alcohol method (alternative method)  
 
7.3.1.       Principle   
 
The air content of the mortar is determined from the reduction in volume which occurs when the air is expelled 
by a liquid.  
 
7.3.2.       Apparatus  
 
7.3.2.1.  Measuring cylinder, approximately 50 mm in diameter, with a capacity of 500 ml and with 5 ml 
graduations.  
 
7.3.2.2.  Rubber bung, fitting the measuring cylinder.  
 
7.3.2.3.  Funnel, fitting the measuring cylinder and suitable for filling it with mortar.  
 
7.3.2.4.  Mixture, of 60 % by volume alcohol (ethanol) and 40 % by volume water. A sufficient quantity of 2 -
octanol may be used in place of ethanol.  
 
7.3.3.            Procedure  
 
Place approximately 200 ml of mortar into the cylinder using the funnel, taking care to avoid  cavities in the 
mortar. Tap the cylinder to level the mortar surface and release entrapped air. Record the mortar volume (V m) 
to the nearest millilitre. Pour the mixture of alcohol and water carefully into the cylinder up to the 500 ml mark.  
 
Seal the cy linder with the rubber bung and invert 20 times to obtain a complete dispersion of the mortar in the 
alcohol -water mixture. Let the dispersion settle for (5.0 ± 0.5) min and read the resulting liquid level to the 
nearest millilitre. Repeat this process unt il two successive readings do not differ by more than 1 ml. With this 
liquid level (V v) calculate the air content (A) of each mortar sample as a percentage of the original mortar volume 
from the following formula to the nearest 0.1 %:  
 
𝐴=[(500−𝑉𝑣)/𝑉𝑚]100 
 
 
where  
 Vm is the volume of mortar, in millilitres;  
  Vv is the volume of mortar plus liquid after shaking, in millilitres.  
 
Calculate the average value of the two individual air contents to the nearest 0.5 %. If the two individual values 
deviate more than 10 % relatively from their average value, test two additional samples and calculate a new 
average value. Report the result a s the air content to the nearest 0.5 %.  
  
 
Key  
1 sample container  
2 cover  
3 clamp  
4 pump  
5 discharge valve  
6 correction valve  
7 ball valve  
8 pressure gauge  
9 pressure chamber  
 
Figure 3 — Schematic diagram of an air content meter