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UDC 667.62 : 620.113
IS0
I NT ERN AT I ON A L ORGAN 12 AT I ON FOR STAN DA RD IZATl O N
IS0 RECOMMENDATION
R 842
SAMPLING RAW MATERIALS
FOR PAINTS AND VARNISHES
1st EDITION
October 1968
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 842, Sampling raw materials for paints and varnishes, was drawn
up by Technical Committee ISO/TC 35, Paints, varnishes and related products and their raw materials,
the Secretariat of which is held by the Nederlands Normalisatie-instituut ("1).
Work on this question led, in 1963, to the adoption of a Draft IS0 Recommendation.
This first Draft IS0 Recommendation (No. 731) was circulated in June 1964 to all the IS0
Member Bodies for enquiry. As the results of this consultation were not considered satisfactory, the
Technical Committee presented a second Draft IS0 Recommendation which was circulated to all
the Member Bodies in September 1966 and which was approved, subject to a few modifications of an
editorial nature, by the following Member Bodies :
Argentina Greece South Africa, Rep. of
Australia Hungary Spain
Belgium India Switzerland
Brazil Iran Turkey
Canada Ireland U.A.K.
Chile Italy United Kingdom
Czechoslovakia Japan U.S.S.R.
France Netherlands
Germany Portugal
One Member Body opposed the approval of the Draft :
Sweden
The second Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in October 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 842-19æ (E)
IS0 Recommendation R 842 October 1968
SAMPLING RAW MATERIALS
FOR PAINTS AND VARNISHES
INTRODUCTION
Correct sampling is a difficult process and one that requires most careful attention. It is therefore
essential that it should be carried out under the supervision of an experienced sampler.
The procedures given below are recognized as good practice and it is strongly recommended that they
be followed whenever practicable. It is recognized that it is difficult to lay down fixed rules to be
followed in every case and particular circumstances may render some modification of the methods
desirable. The aim always to be kept in view is that the sample obtained should be properly repre-
sentative of the bulk.
1. SCOPE
This IS0 Recommendation describes methods for the sampling of raw materials for paints and
varnishes and describes and illustrates apparatus that can be used for this purpose. Suitable methods
are included for sampling oils and other non-volatile liquids, volatile liquids such as solvents, and dry
powders such as pigments and extenders.
The sampling of shellac is dealt with in IS0 Recommendation R 56, Specification for shellac, which
may be used, with suitable modifications, as a general guide for sampling other natural resins.
2. DEFINITIONS
For the purpose of this IS0 Recommendation, the following definitions apply :
2. I Batch, lot. A definite quantity of a particular product produced under conditions which are
presumed uniform.
k
2.2 Consignment. A quantity of some product delivered at one time. The consignment may
consist of one or more batches or parts of batches.
2.3 Sample. A definite quantity of material taken from a larger bulk and intended to provide
information necessary for assessing a characteristic of that bulk.
2.4 Gross sample. A sample as collected.
Reduced sample. A sample obtained by applying a method of reduction to the gross sample.
2.5
2.6 Top sample. A sample taken at not more than 15 cm below the top surface of the material
in a container.
2.7 Middle sample. A sample taken at one-half of the depth of the material in a container.
2.8 Bottom sample. A sample taken at the lowest part of a container.
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ISO/R 842-1968 (b
3. CLEANLINESS SAFEGUARDS
Special care is necessary to ensure that all sampling apparatus is clean and dry when used. Sampling
instruments may first be cleaned with an appropriate (mineral) solvent and subsequently with a
hot solution of soap or with another detergent, care being taken to wash away the last traces with
scalding hot water. If a source of steam is available, the instruments may receive a final cleansing
in a jet of steam, Finally, the operator should ensure that the apparatus is thoroughly dry.
Throughout the sampling operation the operator should have clean hands.
Sampling should be carried out in such a manner as to protect the samples, the material being
sampled, the sampling instruments and the containers in which the samples are placed, from adventitious
contamination, such as by rain, dust, etc.
Material adhering to the outside of the sampling instrument should be removed before the contents
are discharged. The sampling instruments should be emptied and cleaned immediately after sampling.
4. CONTAINERS FOR SAMPLES
For liquid samples, the containers used should be either bottles of colourless or amber glass, or metal
cans. For pastes, mixtures of liquids and solids, or solids, wide-mouth nietal cans or glass jars should
be used. in any case, the container and its stopper should be of a material which will not contaminate
the sample.
Bottles and jars of colourless glass have the advantage that their cleanliness can be visually checked
and also that they enable a check to be made easily on whether the sample contains free water or other
impurities. Bottles and jars of amber glass provide only a relative protection against the action of
light; for materials particularly sensitive to the action of light, complete protection should be
obtained by putting the bottle or jar in a cardboard box or by covering it with black paper.
Galvanized or aluminium cans or stoppers should not be used for the sampling of volatile alcoholic
materials. Glass bottles and jars should be closed either by cork or glass stoppers or by screw caps. In
the case of metal cans intended for liquids, only screw caps should be used. For other metal cans.
either a screw cap or a suitable lid providing a tight closure should be used. Rubber stoppers should
not be used. Cork stoppers should be of good quality, clean and devoid of cracks or pieces of cork
which are liable to become detached. Contact between cork and sample should be prevented by cover-
ing the stopper with tin or aluminium foil* before inserting it in the bottle or jar, unless otherwise
directed. If bottles or jars with ground glass stoppers are used, their freedom from leakage should be
checked. Screw caps are more satisfactory if protected by a cork disk covered with tin or aliiminiuni
foil*, or any other material which cannot contaminate the sample.
5. SAMPLING INSTRUMENTS
5.1 Types and construction
To make sure that the sampling instruments will not be attacked by the products. and that they
can be easily cleaned, they should be made of stainless steel, brass or glass**. and should have
smooth surfaces, without folds or grooves. Examples of suitable instruments are described
below; those for sampling liquids are illustrated in Figures 1 to 10. and those for sampling
solids in Figure 1 1.
*
Aluminium foil should not be used with alcoholic materials. Polytetrafluorethylene foil can generally he used.
** Copper-bearing metals should not be used when sampling vegetable oils.
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ISO/R 842-1%8 (t
5.2 Instruments for sampling oils and volatile liquids
The instruments described in clauses 5.2.1 to 5.2.5 are made in various sizes to hold from
150 ml to 1 litre of liquid.
5.2.1 Sampling bottle or can (Fig. I). This is suitable for sampling large vessels and tanks. It
consists of a weighted bottle or metal container, with removable stopper or cap to which is
attached a suitable chain, pole or cord. This device is lowered to the various desired depths
where the stopper is removed and the container allowed to fill.
ir)
c
FIG. 1 - Sampling bottle
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lSO/R 842-1968 (E)
I
5.2.2 Sampling tipping dipper (Fig. 2). This consists of a cylinder IS cm long and 5 cm in diameter
carrying an extension with a hole at its closed end and a stout wire handle at the open end;
the handle carries a small metallic catch and a rope; the cylinder is inverted in the position
shown in Figure 2 (a), and maintained in that position by insertion of the catch into the
hole. It is then sunk into the liquid in the tank and at the required depth the rope is twitched.
The cylinder rights itself and then becomes full of liquid (Fig. 2 (b)).
(a) Lowering position
(b) Filling position
FIG. 2 - Sampling tipping dipper
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ISO/R 842-1968 (E)
5.2.3 Sampling cylinder (Fig, 3). This consists of an open-headed cylinder with a bottom valve
which remains open whilst the instrument is being lowered through the liquid, ensuring
that an even flow of liquid passes through the cylinder.
When lowering ceases, the valve closes and a sample of the liquid is drawn from the depth
reached by the instrument.
Enlarged section of valve
FIG. 3 - Sampling cylinder
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ISO/R 842-1968 (I
5.2.4 “Go devil”samp1ing bottle (Fig. 4). This consists of a bottle heavily weighted at the bottom,
30 cm long, 7.5 cm in body diameter, and 2.5 cm in neck diameter, with a chain attached to
the neck. When placed in liquid in a tank, it drops so quickly that it does not begin to fill
with liquid until it reaches a fured position.
5.2.5 Bottom ,or zone sampler (Fig. 5). This is suitable for withdrawing bottom samples or zone
samples at any level from tanks of liquid. To withdraw a bottom sample, the apparatus is
attached to a cord or chain and lowered empty to the bottom of the tank where the central
spindle valve automatically opens and the container fills from the bottom. On withdrawal
the valve automatically closes again.
To withdraw a sample at any level, the apparatus is lowered empty to the required level and
then by means of an additional cord, previously attached to the top of the central valve
spindle, the valve is opened and the container filled. The valve is then allowed to close
and the container withdrawn.
base
FIG. 4 - “Go devil“ sampüng bottle FIG. 5 - Bottom or zone sampler
(sectional view)
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ISO/R 842-1968 (E)
5.2.6 Sampling tubes (Fig. 6 and 7). The sampling tube shown in Figure 6 consists of two
concentric metal tubes closely fitted into each other throughout their entire length, so that
one tube can be rotated within the other. A longitudinal opening or series of openings of
about one-third of the circumference is cut in both tubes. in one position the tube is open
and admits the liquid; by turning the inner tube it becomes a sealed container.
The inner tube is 2 to 4 cm in diameter. It may be undivided in its length, in which case the
two tubes are provided with V-shaped ports at their lower ends, so placed that liquid
contained in the instrument can be drained through them when the longitudinal openings
are open.
Alternatively, the inner tube may be divided transversely into from three to ten compart-
ments, in which case the bottom ports are omitted. Such an arrangement enables separate
samples of liquid to be withdrawn from different depths in the container.
The tube should be of sufficient length to reach the bottom of the barrel or container. it
is inserted closed, then opened to admit the liquid and finally closed and withdrawn.
The sampling tube shown in Figure 7 may be used where the liquid to be sampled is known
to be homogeneous in character. It consists of a metal or thick-walled glass tube which may
vary from 2 to 4 cm in diameter and from 40 to 80 cm in length. The upper and lower ends
are conical and narrow down to about 0.5 to 1 cm. At the upper end there are two rings to
assist handling.
To take an individual sample, the tube is first closed at the top with the thumb or a stopper,
and lowered until the desired depth is reached; it is then opened for a short time to admit
the liquid and finally closed and withdrawn.
5.2.7 Valve sampling tube (Fig. 8). This consists of a metal tube with a valve at the base connected
by a central rod to a screwed handle at the top. When the handle is screwed down the valve is
kept closed. it differs from the tubes previously described in that it is inserted into the liquid
with the valve open, allowing the liquid to enter as the tube dips below the surface while the
displaced air passes through an air hole at the top of the tube. When the base of the tube
touches the bottom of the container, the valve automatically closes. The handle is then
screwed tight so as to keep the valve shut, and the tube containing the sample is withdrawn.
The outside of the tube is wiped clean unless the cleaning device (described in clause 5.2.9
below) is used. Sampling tubes of various lengths are used, one 2 m long, made of aluminium,
being convenient for sampling road tanks.
This instrument is not suitable for use where sediments have accumulated.
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ISO/R 842-3968 (E)
FIG. 7 - Sampling tube
with singie tube
FIG. 6 - Sampling tube consisting
of two concentric tubes
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ISO/R 842-1968 (I
5.2.8 Sampling scoop for liquids (Fig. 9). This is of metal and is divided into compartments
along its length, but it is of D - shaped cross-section and is opened and closed by means of a
shutter which moves vertically throughout the entire length. it may be from 2.5 to 5 cm
in diameter.
The instrument is inserted closed, and the shutter pulled out to admit the liquid; the scoop
is then closed and withdrawn.
Enlarged section A-A
Shutter
FIG. 9 - Sampling scoop for liquids
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iSO/R 842-1968 (E)
5.2.9 Sampling tube withdrawal cleaner (Fig. IO). This is a funnel-shaped metal cu
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