I n tern ati on al

Stan d ard 649/I

l N TE RN ATl ON ALORG AN l ZATl ON FOR S TAN D ARD I ZATI D N ~ M E M W’ H AP OAH AR OP I ’ AH #BAl &i R fl 0 C TAH /J AP TG ( 3 AU H M WR G AN l S ATl ON I N TE RN ATI ON ALE DE h ORM ALl S ATl ON

Laboratory g l assware - Den si ty h yd rometers for g en eral

pu rpo ses -

Part 1 : Speci fi cati on

Verreri e d e l aboratoi re - Art 5omBt res B m as s e vol u mi q u e &u s ag e g &&al - Parti e 1 : Sp&i fi cati on s

Fi rst ed i ti on - 1 981 - 0 8- 1 5

E! U DC 531 . 756. 3 Ref. N o. I SO649/1 - 1 981 ( E)

g Descri ptors : g l assware, l aboratory g l assware, h yd romet ers, measu ri n g i n stru men ts, d en si ty ( mass/vol u me) , speci fi cati on s, d i men si on s,

i n terfaci al ten si on , preci si on .

8 Pri ce bas e d o n 9 pag e s

 Foreword

I S0 (th e I nternati on al Org an i zati on for Stan dardi zati on ) i s a worl dwi d e federati on of
nati onal stan d ard s i nsti tu tes (I S0 member bodi es) , Th e work of d evel opi n g I nter-

nati onal Stan d ard s i s carri ed ou t th rou g h I S0 techn i cal commi ttees. Every member
bod y i n terested i n a su bj ect for wh i ch a techn i cal commi ttee h as been set u p h as th e

ri ght to be represen ted on th at commi ttee. I n ternati onal org an i zati on s, g overn men tal
an d n on - g overn men tal , i n l i ai son wi th I SO, al so take part i n th e work.

Draft I nternati on al Stan d ard s ad opted by th e tech n i cal commi ttees are ci rcu l ated to
th e member bod i es for approval before thei r acceptan ce as I nternati on al Stan d ard s by

th e I S0 Cou n ci l .

I n ternati onal Stan d ard I S0 649/l was d evel oped by Tech n i cal Commi ttee I SO/TC 48,
Laboratory g l assware an d rel ated apparatu s, an d was ci rcu l ated to th e member bod i es

i n September 1 979,

I t h as been approved by th e member bod i es of th e fol l owi ng cou n tri es :

Au stral i a I n di a Portu g al

Brazi l I tal y Roman i a

Can ad a Korea, Rep. of Sou th Afri ca, Rep. of
Czech osl ovaki a Li byan Arab J amah i ri ya Spai n .
Fran ce Mexi co U n i ted Ki n g d om

German y, F. R. Neth erl an ds U SSR

H u n g ary Pol an d

N o member bod y expressed d i sapproval of the d ocu men t.

I nternati on al Stan d ard s I S0 649/l an d I S0 649/2, can cel an d repl ace I S0 Recommen -

dati on R 649- 1 969, of wh i ch th ey con sti tu te a tech ni cal revi si on.

0 I ntern ati on al Org an i zati on for Stan dardi zati on , 1 981 0

Pri n tedI n Swi tzerl an d

I N TERN ATI ON AL STAN DARD I S0 649/l - 1 961 (E)

Laboratory g l assware - Den si ty h yd rometers for g en eral

pu rposes -
Part 1 : Speci fi cati on

1 Scope an d fi el d of appl i cati on I S0 6491 2, Laboratory g l assware - Den si ty h yd rometers for

g en eral pu rposes - Part 2 : Test meth od s an d u se. 1 )

I S0 1 766, Gl ass h yd rometers - Con ven ti on al val u e for th e

Thi s part of I S0 649 speci fi es requ i remen ts for fi ve basi c seri es
th ermal cu bi c expan si on coeffi ci enf /for u se i n th e preparati on
of gl ass h yd rometers of constant mass wh i ch are g rad u ated to
of measu remen t tabl es for l i qu i ds) .
i ndi cate densi ty (kg /m3 or g/ml ) at 20 OC.

I S0 3675, Cru d e petrol eu m an d l i qui d petrol eu m produ cts -

Each seri es compri ses h ydrometers wh i ch between th em cover
Laboratory determi n ati on of den si ty or rel ati ve den si ty -
the i nterval 600 to 2 Oookg /ma or 0, 6 to 2, 0 g/ml . Th e
H yd rometer meth od .
h ydrometers are g rad u ated appropri atel y for u se i n l i qui ds of
l ow, med i u m or hi gh su rface tensi on,

3 Basi s of scal e
I t al so speci fi es three su b- seri es of h yd rometers wh i ch are

g radu ated to i ndi cate densi ty at ei ther 20 OC or 1 5 OC. Th ese Th e basi s of scal e shal l be densi ty (mass per uni t vol u me1 i n

h ydrometers h ave smal l er tol erances on scal e error, are l i mi ted ki l ograms per cubi c metre (kg /ma) . Th e u se of g rams per cubi c

to th e ran g e 600 to 1 1 00 kg /ma or 0, 6 to 1 , l g/ml an d are for centi metre (g /cma) , for wh i ch the symbol g/ml may be u sed, i s

u se i n l i qui ds of l ow su rface tensi on. accepted.

N OTE - Th e term mi l l i l i tre (ml ) i s common l y u sed as a speci al n ame

Th i s I nternati onal Stan dard d oes n ot cover h ydrometers wi th a
for th e cu bi c Cen ti metre ( cm?, i n accord an ce wi th a deci si on of th e
bui l t-i n th ermometer, for wh i ch a separate I nternati onal Stan -
twel fth Con feren ce Gen eral ed es Poi ds et Mesu res. Th e term mi l l i l i tre
d ard i s u n d er consi derati on. Th e h yd rometers compl y wi th the
i s acceptabl e, i n g en eral , for referen ce to capaci ti es of vol u metri c
requ i remen ts of I S0 367. gl assware an d i s u sed i n th e presen t text.

A tabl e of stan dard categori es of su rface tensi on i s gi ven i n

an n ex A. A tabl e of recommen d edstem di ameters i s gi ven, for 4 Referen ce temperatu re
g u i dan ce i n man u factu re, i n an n ex B.
4. 1 Th e reference temperatu re for densi ty hydrometers,
Part 2 of thi s I nternati onal Stan d ard deal s wi th test meth od s excl u di ng th e speci al su b-seri es L5OSP, M 5OSP an d SSOSP,
an d u se of densi ty hydrometers. shal l be 20 OC. Wh en u sed i n a l i qui d at thi s temperatu re, the
h ydrometer shal l i ndi cate the densi ty of the l i qui d at 20 OC.

4. 2 Th e referen cetemperatu re for densi ty h ydrometers of the

2 Referen ces speci al su b-seri es LSOSP, M 5OSP an d S5OSP shal l be ei ther

20 OC or 1 5 OC. Wh en u sed i n a l i qui d at the appropri ate

I S0 387, H yd rometers - Pri n ci pl es of con stru cti on an d aoj ’ u st- temperatu re, th e h ydrometer shal l i ndi cate the densi ty of the
men t. l i qui d at that temperatu re.

1) At presen t at th e stag e of draft, (Revi si on , i n part, of I SO/R 649. )

1
IS0 649/l-1 981 (El

5 Surface tension 8.2 The loading material shall be fixed in the bottom of the
hydrometer, After the finished hydrometer has been kept in a
The adjustment shall be related to specific capillary conditions horizontal position for 1 h at 60 OCand subsequently cooled in
as follows : that position, the instrument shall meet the requirements of
9.3.
5,l When the hydrometer is slightly displaced from its
equilibrium position in a liquid, the stem passes through the 8.3 The strip on which the scale and inscriptions are marked
liquid surface without causing any apparent alteration in the shall have a smooth matt surface. The strip shall show no
shape of the meniscus. evidence of charring. The strip bearing the scale shall not
become discoloured or distorted when the stem is exposed for
5.2 The hydrometer scale shall be adjusted either for a given 1 h to a temperature of SOOC.
liquid having a given surface tension, or for one of the standard NOTE - If a hydrometer is intended to be used at a temperature above
categories of surface tension given in annex A. Except where 80 OC, the loading material and the strip bearing the scale shall meet
the highest precision is required, one of the standard categories the requirements of 8.2 and 8,3 at a temperature slightly above the
of surface tension given in annex A shall be used, temperature of use.
For hydrometers of the highest precision, intended for use in
particular liquids (for example alcohol solutions), the surface 8.4 There shall be no loose material in the instrument.
tension values appropriate to clean surfaces of these liquids
and to the actual indications of the hydrometer shall be used
[see clause 1 4 ~1 1 . 9 Form
The sub-series LSOSP,M5OSPand SSOSPare limited to the low 9.1 The outer surface shall be symmetrical about the main
surface tension category. axis.

9,2 There shall be no abrupt changes in cross-section. The

6 Reference levels for adjustment and tapered design shown in figure 1 is preferred, but any design
reading which does not permit air bubbles to be trapped is acceptable.

6.1 The scale of the hydrometers shell be adjusted for

readings taken et the level of the horizontal liquid surface.
NOTE- If a hydrometer having a scale so adjusted is used in an
opaque liquid, readings may be taken at the top of the meniscus where
it appearato meet the stem, but an appropriate correction to the level
of the horizontal liquid surface should then be made. (See part 2 of this
International Standard). Alternatively, hydrometers intended for use in
opaque liquids may be adjusted for readingsat the top of the meniscus.

6,2 The middle of the thickness of a scale line shall be taken

as ita definitive position.

7 Immersion
Hydrometers shall be graduated for use with the emergent
stem dry, except in the immediate vicinity of the meniscus.

8 Materials and workmanship

8.1 The bulb and the stem shall be made of a suitable
transparent glass, selected and processed to be as free as
possible from stress and visible defects, and having a coeffi-
cient of cubical thermal expansion of (25 & 21 x 1 0-s OC-I*, Figure 1 - Preferred design of hydrometer bulb

l This value complies with IS0 1 768.

2
 I SO649/1 - 1 961 ( E)

9. 3 Th e h ydrometer shal l fl oat wi th i ts axi s verti cal to wi thi n i magi nary l i ne paral l el to th e axi s of th e i nstru ment. I n the l atter

I , 5 O of arc. two cases, th e verti cal l i ne may al ternati vel y be marked .

9. 4 A th ermometer shal l n ot form part of a h yd rometer con -

1 0. 3 Seq u en ce of g radu ati on l i nes
formi ng wi th thi s I nternati onal Stan d ard (see cl au se I ) .

1 0. 3. 1 On h yd rometer scal es wh ose smal l est i nterval is

1 kg /ma or 0, 001 g/ml :

10 Scal e
a) every tenth g radu ati on l i ne shal l be a l ong l i ne;
Exampl es of recommen d ed scal es for th e h ydrometers are
i l l ustrated i n fi gure 2. b) th ere shal l be a med i u m l i ne between two consecu ti ve

l ong l i nes;

1 0. 1 Gen eral
c) there shal l be fou r short l i nes between consecu ti ve

med i u m an d l on g l i nes.
1 0. 1 . 1 - Th e stri p on wh i ch the scal e an d i nscri pti ons are

marked shal l remai n secu rel y fasten ed in pl ace at th e

1 0. 3. 2 On h ydrometer scal es wh ose smal l est i nterval is
temperatu re of u se (see 8. 31 .
2 kg /m3 or 0, 2 kg /m3 or 0, 002 g/ml or O, OfXl 2g/ml :.

1 0. 1 . 2 Appropri ate mean s shal l be i n corporated for en su ri n g

a) every fi fth gradu ati on l i ne shal l be a l ong l i ne;
that an y di spl acemen t of th e scal e or of the stri p beari n g th e

scal e i s readi l y apparen t. An y di spl acement ren ders th e i nstru- b) th ere shal l be fou r short l i nes between two consecu ti ve
men t u nsui tabl e for u se, l ong l i nes.

1 0. 1 . 3 N o h ydrometer shal l h ave more th an on e type of scal e.

1 0. 3. 3 On h ydrometer scal es wh ose smal l est i nterval is
I f a h ydrometer h as dupl i cate scal es, th e val u es i ndi cated by
5 kg /ma or 0, 005 g/ml :
th em shal l not si gni fi cantl y di ffer, an d both scal es shal l compl y
wi th the requ i remen ts of cl au se 1 3.
a) every tenth g radu ati on l i ne shal l be a l ong l i ne;

1 0. 1 . 4 Th e scal e l i nes an d i nscri pti ons sh ou l d preferabl y be b) th ere shal l be fou r med i u m l i nes between two con-

bl ack an d shal l be cl earl y an d du rabl y marked. secuti ve l ong l i nes;

c) th ere shal l be on e short l i ne between two consecu ti ve

1 0. 1 . 5 Th e scal e shal l be strai ght an d wi thou t twi st.
med i u m l i nes an d between consecu ti ve med i u m an d l ong
l i nes.
1 0. 2 Gradu ati on l i nes

1 0. 2. 1 Th e g radu ati on l i nes shal l be di sti nct an d of u ni form 1 0. 4 Fi gu ri ng of gradu ati on l i nes
thi ckness not exceedi n g 0, 2 mm. For th e SP seri es, th e
thi ckness of th e g radu ati on l i nes shal l n ot exceed 0, 2 mm.
1 0. 4. 1 Except i n th e case of dupl i cate scal es, th e scal e shal l
h ave onl y on e set of n u mbers, an d the l astdi gi tsof th en u mbers
1 0. 2. 2 Th ere shal l be n o evi dent l ocal i rregul ari ti es i n th e spac- shal l be verti cal l y al i gned.
i ng of the gradu ati on l i nes.

1 0. 4. 2 Th e scal e shal l be fi gured so as to en abl e the val u e cor-

1 0. 2. 3 Th e g radu ati on l i nes shal l be perpen di cu l ar to th e axi s respon di n g to an y g radu ati on l i ne to be readi l y i ndenti fi ed.
of the h ydrometer.

1 0. 4. 3 Th e hi ghest an d l owest g radu ati on l i nes of the n omi n al

1 0. 2. 4 Th e scal e shal l be strai ght an d wi thou t twi st. l i mi ts shal l be fi gu red i n ful l .

1 0. 2. 5 Th e short, med i u m an d l ong scal e l i nes shal l extend, 1 0. 4. 4 At l east every tenth l i ne shal l be fi gu red.
respecti vel y, at l east one-fi fth, one- thi rd an d one- hal f of the
way rou n d the ci rcu mference of the stem.
I O. 45 For densi ty val u es expressed i n g rams per mi l l i l i tre, th e

deci mal si gn shal l be i ncl u ded for n u mbers expressed i n ful l ,

1 0. 2. 6 Th e hi ghest an d l owest g radu ati on l i nes i ndi cati ng th e bu t may be omi tted from abbrevi ated n u mbers.
nomi n al l i mi ts of th e scal e shal l be l ong l i nes (see 1 0. 3. 1 , 1 0. 3. 2

an d 1 0. 3. 31 .

1 0. 5 Exten si on of scal e
1 0. 2. 7 Th e short, med i u m an d l ong l i nes shal l each be ver-

ti cal l y di sposed so that ei ther th e mi d-poi nts, or th e ri ght h an d Th e scal e shal l be exten ded beyon d the nomi n al scal e l i mi ts as

en ds or the l eft h an d en d s of al l g radu ati on l i nes shal l l i e on an i ndi cated i n tabl e 1 .

3
ISO949/1 =1 991 (E)

0,8=00 1 300:
0,8 -EE@) 1 3ooE
-= --
-
022= -05 052-
=02 7

ilLI=
=- --=1 0 lo=
--

06-z L

- 71 5 1 53
--
E
=08 ostx
-- --
202
El0 1 oz -
-= -25 25 =
1 2- --
- --
-
730 3-z
-1 4 14 - --
- --
-
,sE
-
-35 353
--
- --
-
ZlS 1 82 -40 &gJe
- --
zz= -- - -
-
0,8 -c20
- 1 I-320 z
- =45 452
-- - --
a -
-
IJO Series 0,8-50 1 3502
--
L50and L5lBP Series

Figure 2 - Recommended scales

4
 I SO&Wl - 1 9 8 1 ( E)

0 , 8= Co o
0, 8- 00 1 300=

-
-
-

-
-
-
- 48 40=
-

- -
-

- 30 30=

-
-
- -
-
-
- -
-
- 80 8030
0, 8- 50 1 3! 50= -

v
- -

-
-
M50 an d M S OS P Seri e s

Ml 00 Se ri e s

0, 8 ~ 00
0 , 8= 00 1 3001 -"
-
-

= 1 0 1 01

-
-

= 20

-
-

=30

- =
-
=40 40 0 . g 40
- =
- =
0, 8= 50 1 35033
0 , 83 0
7

S 5 Q Seri es - S WS P Su b- Se ri e s

fo r typi cal h yd ro m e t e rs
 Tab l e 1 - Pri n ci pal re q u i re m e n t s for s e ri e s of h yd ro m e t e rs

Vo l u m e

bel ow E xt e n s i o n of

N o m i n al Mi n i mu m l o we s t s cal e at e ach
Bu l b
M axi m u m ran g e N u mber of s cal e s cal e g rad u at i o n en d b e yo n d
d i am e t e r
total of d i vi s i o n s x val u e of l en g th l i ne of u pper an d

Se ri e s l en g th e ach th e s cal e i n t e rval ( n o m i n al n o m i n al l o we r

h yd r o m e t e r ran g e ) ran g e n o m i n al

l i mi ts
mi n , m ax . mi n . m ax .

mm kg /m 3 g /m l kg /m 3 g /m l mm mm mm ml ml g rad u at i o n I i n e E

I 20 335 20 0, 020 1 00 x 0, 2 l oo x 0, ooo 2 1 05 36 40 1 03* 1 32 5to 1 0

L5 0 335 50 0, 050 1 60x0 , 5 1 06x0 , 0 665 1 25 23 27 50* 65 2 to 5

M! i O 270 50 0, 050 8 0 X1 50 x 0, 001 70 m 24 30 45 2 to 5

M l OO 256 1 06 0, 1 00 58 x2 50 x 0, 002 85 1 8 20 1 8 26 2 to 5

550 1 90 60 0, 050 25 x 2 25 x 0, 002 50 1 8 20 1 8* 26 2 o r3

Spe ci al

s u b- s e ri e s t

L5o SP 335 50 0, 050 1 0 6 x0 , 5 1 0 0 x0 , 0 665 1 25 23 27 50 65 2 to 5

M B &P 270 50 0, 050 5 0 x1 50 x 0, 001 70 m 24 30 45 2 to 5

S5 f l SP 1 90 50 0, 050 50x1 5- o x 0, l xl l 50 1 8 20 1 8, 26 2 or 3

Fo r t h e d i am e t e r o f t h e s t e m t o e x ce e d 4 m m ( as re q u i re d b y 1 2 . 41 ,t h e s e vo l u m e s , for h yd r o m e t e rs co ve ri n g t h e ran g e 1 7 0 6 t o 2 0 6 0 kg /m 3 o r I , 7

t o 2 , 0 g /ml , wi l l b e n e are r t h e m a x i m u m val u e t h an t h e m i n i m u m val u e .

t S e e I S0 3 6 7 5 .

1 1 R an g e s of th e s e ri e s of h yd ro m e t e rs 1 2. 4 No h yd ro m e t e r sh al l h ave a s t e m of d i ame t e r s mal l e r

th an 4, 0 m m .

E ach of th e fi ve m ai n seri es of h yd ro m e t e r sh al l co ver a total

ran g e of 6 0 0 to 2 0 0 0 kg /m a or 0 , 60 6 to 2, 0 6 0 g /ml , e ach N OTE - Fo r co n ve n i e n ce i n m an u f act u re , i t h as b e e n f o u n d ad van -

t ag e o u s t o co m p l y wi t h th e r e co m m e n d at i o n s as t o stem d i am e t e r
h yd ro me t e r h avi n g a ran g e of 2 0 kg /m s , 5 0 kg /m a or
g i ve n i n an n e x B.
1 0 0 kg /m 3 or 0 , 0 20 g /ml , 0 , 0 5 6 g l mi or 0 , 1 0 0 g /ml . Th e l ower

n o m i n al l i mi ts of th e scal e s of t h e L20 . seri esh yd ro me t e rs sh al l

be 6 0 0 , 82 0 , 640 , etc. , or 0 , 60 0 , 0 , 620 , 0 , 640, etc. , th o se of th e

L5 0 , M 5 6 an d S 5 6 seri es h yd ro me t e rs sh al l be 60 0 , 656 , 70 0 ,

etc. , or 0 , 60 0 , 0, 650, 0 , 70 0 , etc. , an d t h os e of th e M 1 0 6 seri es

1 3 Accu r acy
sh al l be 6 60 , 760 , 80 0 , etc. , or 0 , 660 , 0 , 70 0, 0 , 806, etc. , accor-

d i n g to wh e t h er th e scal e s are bas e d o n ki l o g rams per cu bi c

Fo r h yd ro m e t e rs th e m a x i m u m pe rmi t te d i n stru me n t errors at
m e t re or g ram s per mi l l i l i tre.

an y poi n t o n th e scal e are g i ve n i n tabl e 2. I t i s r e co m m e n d e d

th at th e h yd ro m e t e rs i n th e speci al su b- seri es be su ppl i e d wi t h

E ac h o f the t h re e su b- seri es of h yd ro m e t e rs sh al l co ve r a total

certi fi cates of correcti on , wh e n req u i red for ref eren cepu rpo se s.
ran g e of 6 0 0 to 1 1 0 0 kg /m 3 or 0 , 66 6 to 1 , 1 0 6 g /ml , e ach

h yd ro m e t e r h avi n g a ran g e of 5 0 kg /m a or 0 , 0 50 g /ml . Th e

l ower n o m i n al l i mi ts of th e scal e s of t h e L5 OS P , M 5 O S Pan d

S 5 OS Psh al l be 60 0, 650 , 70 0 , etc, , or 0 , 606, 0 , 650 , 0 , 70 6, etc. ,

accord i n g to wh e t h e r th e s cal es are bas e d o n ki l o g ram s per Tabl e 2 - Maxi mu m pe rm i t t e d e rro rs

cu bi c m e t re or g ram s per mi l l i l i tre.

M axi m u m pe rm i t t e d e rro r

Se ri e s
at an y po i n t on th e s cal e
1
1 2 Pri n ci pal d i men si on s kg /m 3 g /m l

I 20 . f 02 f o , o oo 2

1 2. 1 Th e d i m e n s i o n s of th e h yd ro me t e rs sh al l co n f o rm wi th L5 0 f 0, 5 f 0, 0085

th e re q u i re men t s g i ven i n tabl e 1 . M56 z i zI , 0 f 0, 001

Ml 00 f 2, o f 0, 002

S50 f 2, o rt: o , ob2

1 2, 2 Th e cross- secti on of th e s t e m sh al l re mai n u n ch an g e d

forat l east 5 m m be l o w t h e l o wes t g rad u ati on l i n e o n th e scal e, Spe ci al s u b- s e ri e s

L B OS P f 0, 3 f 0, 0663

M B OS P + 083 f O, C 0 0 6
1 2. 3 Th e s t e m sh al l e xt e n d u n ch an g e d i n d i ame t e r at l east
S5oSP f 1 ,o & 0, 001 0
1 5 mm ab o ve th e u ppermo st g rad u at i o n l i ne on th e s cal e .

6
 I S0 649/l - 1 981 (E)

14 I n scri pti on s d) wh eth er the h yd rometer i s adj u sted for readi ng s at the

top of th e meni scu s (Le. for u se i n opaq u e l i qui ds) ;

Th e fol l owi ng i nformati on shal l be perman entl y, l egi bl y an d
u nequ i vocal l y marked wi thi n the h ydrometer :
e) the maker’ s an d/or ven dor’ s n ame or readi l y i denti fi abl e

a) the basi s of th e scal e, for exampl e “kg /ma”; mark;

b) the referen ce temperatu re of the h ydrometer, for

f) i denti fi cati on n u mber of the i nstru ment, the fi rst two
exampl e “20 OC”;
di gi ts of wh i ch may i ndi cate the year of man u factu re (for
exampl e “7KKKI 1 ”) ;
c) 1) ei ther a parti cul ar su rface tensi on expressed i n
mi l l i newtons per metre (for exampl e “55 mN /m”) ;

g) the n u mber of thi s I nternati onal Stan dard (i . e,

2) or a su rface tensi on categ ory as defi n ed i n an n ex A
I S0 6491 1 ) or the n u mber of the correspondi n g nati onal
(for exampl e “l ow S. T. “) ; stan dard;

3) or, i f th e i nstru ment i s adj u sted for u se i n a parti cu l ar

l i qui d, th e n ame of that l i qui d; h) the seri es n u mber (for exampl e “L50”) .
I s0649/1 4981 E)

An n ex A

Stan d ard categori es of su rface ten si on for h ydrometers

(Th i s an n ex forms part of th e Stan dard. 1

Th e stan d ard categori es of su rface tensi on gi ven i n tabl e 3 are Atten ti on i s d rawn to th e req u i remen ts of cl au se 1 4 c) ,

ad opted for h yd rometers for tech n i cal u se, so as to provi de a

preci se basi s for adj u stmen t an d veri fi cati on an d to permi t th e Tabl e 3 sh ows th e su rface ten si on s for th e adj u stmen t of

attai nmen t of the appropri ate accu racy i n measu remen tsi n th e h yd rometers rel ated to th e mi n i ma of th ei r den si ty ran g e.

l i qui ds i ndi cated. . Th e adopti on of th ese su rface tensi on

categori es does not precl u de th e u se of oth er su rface tensi ons I f su rfaces of aq u eou s sol u ti on s ( except th ose of aceti c aci d

as th e basi s for th e adj u stmen t of h ydrometers, provi ded su ch an d of ni tri c aci d of den si ty g reater th an 1 3 0 0 kg /m3 or

su rface tensi ons are marked , i n mi l l i newtons per metre, wi thi n I , 3 g/ml ) are speci al l y cl ean ed, for exampl e by overfl ow, th en

th e h yd rometers or referen ce i s mad e to th e type of the l i qui d. the su rface tensi on i s i ncreased to approxi matel y 75 mN /m,

Tabl e 3 - Stan d ard categ ori es of su rface ten si on

Den si ty g/ml 0, oo 0, 02 0. 04 0, 06 o, oa
Exampl e of l i qu i ds to wh i ch
Categ ory
kg /n + g/ml kg /r+ 0 20 40 66 60 th e categ ory i s appropri ate

Su rface ten si on mN /m
Lo w 6m 0, 6 15 16 17 18 19 Org an i c l i qu i ds g en eral l y (i n cl u di n g eth ers,
70 0 087 20 21 22 23 24 petrol eu m di sti l l ates, coal tar, di sti l l atesl , an d
80 6 0, 8 25 26 27 28 29 al l types of oi l s. Aq u eou s sol u ti on s of l ow
900 03 30 31 32 33 34 mol ecu l ar mass org an i c su bstan ces.

1 0 0 0 to 1 3 0 0 1 . 00 to I , 30 35 Aceti c aci d sol u ti ons, th e free su faces of

i ncl u si ve i ncl u si ve wh i ch h ave n ot be en speci al l y cl ean ed, an d

h eavy oi l s.

Med i u m 6ooto840 0, 60 to 0, 94 as for th e “l ow” categ ory above Aq u eou s sol u ti on s of l ow mol ecu l ar mass
i ncl u si ve i ncl u si ve org an i c su bstan ces (i n cl u di n g th ose of
96 0 0, 96 35 eth an ol an d meth an ol , bu t excl u di n g aceti c
970 0, 97 40 aci d sol u ti ons) , th e free su rfaces of wh i ch
h ave n ot bee n speci al l y cl ean ed.
88 u 038 45
99 0 09 50

1 OOOt o 2 0 0 6 l , oo to 2, cKl 55 Ni tri c aci d sol u ti on s of den si ti es g reater th an

i ncl u si ve i ncl u si ve 1 3 0 0 kg /m3 or I , 3 g/ml , wh eth er th e free

su rfaces h ave bee n speci al l y cl ean ed or n ot.

Hi gh 1 0 30 t 0 2600 1 , oo to 2, rXr 75 Aq u eou s sol u ti on s, th e su rfaces of wh i ch

i ncl u si ve i ncl u si ve h ave be en speci al l y cl ean ed, except :

a) ni tri c aci d of den si ty g reater th an

1 3 0 0 kg /m3 or I , 3 g/ml :

b) aceti c aci d sol u ti onsl r.

1) Aceti c aci d sol u ti on s sh o w extreme vari abi l i ty of su rface tensi on .

8
 I SO649/1 - 1 981 ( E)

An n ex B

Recommen d ed stem di ameters for h ydrometers

Th e d i ameters sh own i n tabl e 4 are not man datory. Th ey are i n ten ded for g u i dan ce i n man u factu re.

Tabl e 4 - Recomme n d e d stem di ameters

Seri es Seri es
Upper l i mi t of
KO, L50, M50, Ml W SW
nomi n al ran g e
L5oSP an d M WS P an d S SOS P

kg /m3 g/ml mm mm mm

60 0 0, 6 66 7, l 64

70 0 0, 7 61 683 53

80 0 On 8 5, 7 62 5, 5

900 03 5, 4 5, 9 5, 2

1 000 to 5, l 5, 5 49

1 l oo 1 ,l 49 5, 3 4, 7

1 200 12 4, 7 5, o 4, 5

1 300 1 ,3 4, 5 489 4, 3

1 40 0 64 4, 3 4, 7 4, 2

1 500 1 ,5 4, 2 4, 5 4, O”

1 600 1 ,6 4, O” 4, 4 4, O”

1 70 0 1 ,7 4, O’ 4, 2 4, 0*

1 800 1 ,8 4, Of 4, l 4, 0*

1 90 0 1 1 ,9 1 4, 0* 1 4, 0* 1 4, 0*

* 4. 0 m m i s th e mi n i mu m stem d i ameter permi tted i n 1 2. 4.