antonpaar dma density meter manual

8/12/2019 Antonpaar Dma Density Meter Manual

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DMA Digital Precision Density Meters

Density and density-dependent valuesCalibrationofDen sity M eters

Determinat ionofapparatus cons tantsCalculation Examples

to Pa a r KG.A 8O54 GRAZAUSTRIA -EUROPA


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A) Definition of measuring units

1 . D e n s i t y : p [ k g / m3, g /cm

3jThe density of a homogeneous,solid subst ance, a liquid or

a gas is defined as the volumetric density of its mass(ace.to Austrian LaW, HGBL 17^/1973 , 2 (1) ).

Occasionally one may still find the dimension g/ml;the conversion is

1,000 000 g/ml = 0,999972 g/cm 3

but according to Austrian Law (Gsterr. BGBL. as statedabove) now 1 1 = 0,001 m 3; and, therefo re, this dimensionis out of use.

Conversion factors (Anglo-Saxon Measures)

DENSITY bcuft u n ibge t OK) bgat US)2,768-10 9,938-f0 * 1,198-10

1 602 10 2,768-10 1 9,978-10 1193-10

Lbu t 6,228


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2. Specific Weight :M fkp/m ] ,u[N/rrijIt is calculated out of the acceleration due to gravityand the substance's densityp . It represents the weightper volume unit.

GV

The refo re, a substance with the mass 1 kg weighs 1 kp.It can be written:

thus:

and:

A substance wi th the mass 1 kg (because of m [kg] g / T ~ Jg 9^81 ^ 5 - ^ weighs approx. 9,81 N (lkgms" 2= IN).

Therefore,

Because of the elimination of the unit "POND" ((Jsterr. BGBL)(Austrian Law) the specific weight is allowed to be usedonly until 31.12.1977.


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3. Density Ra tio: d tz [ JThe density ratio - a nondimensional quantity - states ,how many times heavier a solid sub stan ce, a liquid ora gas is at a temperature t2i compared to a referringsubstance of the same volume at a temperat ure t^.There fore, the density ratio represents the relation ofdensity of a substance to the density of a comparison substance;mostly of water at its highest density (4C): j t & _^subztanc*jtzFor example: The density ratio of d^ shows the relation ofdensity of a substance at 20C to water at 4C.

4. Relative density: d* [JIt is the ratio of the density of a solid mate ria l, a liquidor a gas at any temperature to the density of water at thesame te mperature.The ref ore , the relative density is also a nondimens ionalquantity.

d* = fsubst nce jtfwter jt


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5. S.G. Specific Gravity: t 1/t 2 f ]This nondimensional quantity represents the comparison ofthe mass of a given volume of any substance at the temperaturet^ to the mass of the same volume of pure water at a temperaturet 2 (= specific gravity t1 /t 2 ) .In industry, very often t1 and t 2 are the same, namely 60For 15,56C. That is corresponding to the relative density.Further density-dependent units:a) Beaume Index

Liquids heavier than water:Beaume Index = 1 4 5- s p e G i f | c g r avity 60/60 d e S r e e s B e a u m &

Liquids lighter than water:Beaume Index = s p e c i f i e g r a v i t y 6 o / 6 o - 130 degrees Beaume

b) Brix IndexLiquids lighter than water

Brix number = s p e c i f i c gravity 60/60 - 4 0 0 AeSrees Brix

Liquids heavier than waterSugar Industry Index:lBrix =1 sugar by weight.

c) Twaddell Index:Twadd ell Index = 200 (specific gravity 60/60 -1)

d)A.P.I. Index Petroleum Index,

A. P. I. Number = s p e d f ^ r a v i t y 60/60 " 1 3 1 ' 5


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B. Calibration of the Density Meters

'The following values are valid at a pressure of 760 mm Hg; i.e. ,1,013 bar.Our digital density meter DMA 4 5, DMA 4 6. for exa mple , simplifies theaccurate determi nation of the density p of liquids and gasesby reducing the procedure to the electronic measurement of atime period from which the density is calculated automatically.1. Measurement of Density:

Calibration and Measurement at 20C:H 20 : f= 0,998202 [g /c m 3jAir: p = 0,001205 [ g/cm 3]

These density values for air and water may be taken directlyfrom the tables of the DMA - Instruction - Manua ls.By means of the equations used in the manual we obtain:

p = -J L ( T 2 - B) > DMA 45, (is calibrating the' DMA 46 value automat ically)

A, B apparatus constantsT... time period of the measured substance.

The determination of these values is explained in the manuals,too.If instead of de ns it yp the specific gravity or other indicesare desired , then the corresponding values have to be used forcalibration.


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2. Determination ofSpecific Weight:

R f 2 J =*pI^-J anda n a l o g o u sLcm 3J

Also:,. ,IN , g 9^ 8 1 OO12O5 =0,001205 []k fwvter/vc 0,999972

For example: Density RatioofCarbon Tetrachloride

CO - f ^ t e r I i i C 0,999971^94l5_. r 1 > 5 9 4 1 9

That means that carbon tetrachloride at20Cis1,59^19timesheavier thananequal volumeofwaterat 4C.


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Equa lly , the instrument could be calibrated at e.g. 25C :

H 20 : d*S= 0,997071 [jAir: dj* = 0,001185 [J

4. Deter minat ion of relative density*4i

= 1 , 0 0 0 0 0 0

footer /1Calibration and Measurement at e.g. 20C:

H 2 0 : /20C, 0 , 9 9 8 2 0 2

0 , 9 9 8 2 0 2Air.: d* = ? > / ? *f I = 0^001205 = 0,0012070,998202

The relative density is a nondimensional quantit y, too.

5.) Determination of S.G. specific gravity

Mostly, the density of the measured substance is ref^ered tothe density of wate r at the same temperature of 60F = 15,56C(= specific gravity 60/60).Calibrati on and measure ment at 15>56C = 60 P:H 20: specific gravity 60/60 = f^^jis;S6mc _ l a 00 0 0 0 0 [ 1ft-l-iS t


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The equations as stated underA)enablethedeterminationoffurther density units -like Beaume Index, Brix Indexetc.

C. E x a m p l e : Sugar solution1058 byweightDeterminationofdensityanddensity dependentunits.Measuring instrument: D M A 45 ( D M A 46)

EquationsforCalibrationwithair anddistilled water:

Measuring temperature:20 C

Q - -1(T -E

1. ) D e n s i t ya) Calibration

Calibration mediums: Waterand Air=6,4668 fH 0

calculatedautomatically(onlyat DMA 4e.g.,DMA 6 )

g/cm3

Ta ir =0,0012

Determinationofcalibration constants:A= = 41,8195-23>OO450,9982- 0,0012 = l 8 > 8 7 l 6

= Ta i r ( A* f a i r )= - (18,8716.0,0012)=22,9819


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b) Measurement

Measuring value: T g u g a r=6,5182

pp.,*.,.=-h(* ,,- B) = L - (42,4869 - 22,9819)JP s u g a r 54


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/3>)a.Calibrationforspecific weightCalibration me diums: waterand air

T H = 6,4668 it =0,9982 P/cm3

T a i r= 4*7963 f a i r = > 0 0 1 2p/cm3air

Determinationofcalibration constants:A=T H 2 0 Ta i r = 41,8195-23,0045 = l 8 j 8 7 l 6

/w2o -/*> 0,9982- 0,0012

B=T*. - (A . IL ) =23,0045-(18,8716.0,0012)=22,98193.11 Qcilr

b . Measurementofspecific weight

Measuring value: T =6,5182s ugar

i --f f e s ]therefore: s u g a r=1,0335

* 9' 8 1 1033,5-10138

3. ) D e n s i t y R a t i oReference Substance: waterat 4C**)a.Calibrationfordensity:see C)1. a;

b . Density measur ement:see C) l.bjand then calculationof thedesired unit


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11 -With f> =1,0335 g/cm3 weobtain thedensity ratio

z - VSUQQ,Uoc . 1,0335 _ i a?i = 1 >O 3 3 6

f 70,9999

a Calibration for density rat ioCalibration mediums: Water and airT H = 6 4 6 6 8 d * 0= fW/zo-c = 04 282_ -9982 r _H2 *'**


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4. R e l a t - i v e D e n s i t y

ob.Density Measurement:see C)l.b;

and then calculationofthedesired unit:

Withp =1,0335g/cm3weobtaintherelative density

Z - Psucjar jZOeC _ l a 0 3 3 5 _ 1 n - z r h f ]-Z fwater \ZOC 0,9982

fi a Calibrationforrelative densityCalibration mediums: Waterandair

T = 6,4668 U

T = 4,7963 d Ql> = fW ' c = 2i2_ = o,OO12a i r PHOI20 C 0,9982

Determination of cal ibrat ion c onstants:A = Tfa0 - Tq/> = 41,8195 - 23,0045 =

B = Tl i r ( A d,ov } = 23,0045 - (18,8376 . 0,ool2) = 22,9819

b.Measurementofrelative densityMeasuring value: Toi,rt.QV,=6,5182

SUgaP


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_B ) =

18,8376 v0,9982 (42,4869 - 22,9819) =1,0354 []

5.) S.G. S p e c i f i c G r a v i t yCalibration and measurement at 60F = 15,56C

( in industry very often this measuring temperature is used).

O C ) a. Calibr ation for density : see C) l.a)b. Density Measurement: see C) l.b;

and then calculation of the desired unit:

with p =1,0335 g/cm3 we obtain

specific gravity 60/60 = fsu^rjisfs6c=1?Q338l ^ f L fwater 115, 56*0 0,9971

f>> a. Calibration for specific gravity 60/6015 356C:T H n = 6 ,4 65 2 S .G. 6O/6O H n = fH2 H2 fao

At 15 356C:

0,9971

T . =4,7976 S.G. 60/60 . = p,v/is,s*-c = 2^,0018 = O j O O l 8 f Ja i r a i r f^oj^^c 0,9971

Determination of calibration constants:A . JL ~Tair .4 l a7988 - 23,0170 _3.6.60/60^6.60/60^'1 - 0,0016 "^

B = T | i r - (A . S.G .6O /6O a ir) = 23,0170 - (18,8157 . 0,0018) = 22,9831


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b.) Measurement of specific gravity 60/60Measuring value: T g u g a r =6,5142

specific gravity 60/60 = f*"*" / ^ c = 1 (T2S - B )=

(42,4348 - 22,9831) =18,8157 .0,9971

=__l_,O_3_68_ [J ... is read out directly

Further density dependent units -e.g. Brix Index, Beaume Index,Twaddell Index (that are indices of specific gravit y) - can bedetermined easily in dependence of SPECIFIC GRAVITY by meansof the equation as stated under point A ) .

Now the possibility of a calibration on concentration measurementsis illustrated in an example.

Calibration for Concentration measurement of a sugar solutionbetween 10 weight and 20 weight at 20C.

Concentration c = 0,10 g/g9.Concentration c, = 0,20 g/g

C Sugar solution with 10 weightaC b Sugar solution with 20 weight

Density values of these concentrations

Directly displayed at DMA 4 5, f =1,0335g/cm .... with 10 weighti.e., DMA 46:p b =1,0655g/cm .... with 20 weight


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Calibration Measurementat20C

Used calibration mediums: Waterand Air

T H = 6,4668 p n=0,9982 g/cm3

Ta i r = ^ 7 9 6 3 pa i r=0,0012 g/cm3

Therefore,weobtainthefollowing calibration constan ts:

A . = THIO-Tat, = 41,8195-23,0045= l 8 > 8 n 6density 0,9982- 0,0012

dens i ty = Tlir ( A ' f air> = 2 ^ 0 0 ^ ( I8, 87l6 . 0,0012)= 22,9819

Determinationoftime periods fromCoand C, :a

T I = dens i ty + ( Adensity ' f a ) = 22,9819-+ ( I8f87l6 . 1,0335)= 42,4852

Tg s dens i ty + ( Adensity >f = 2 2>9 1 9 + ( l 8 8 7 1 6 * 1>

T and T. mayalsobereceived from T-measurementsofsamplesofa D

known concentrations.Inordertoachievea.direct calculationanddisplayof"concentration"two newapparatus constants A c o n candB are to bestored:


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. 43,0896 - 42,4852

Bconc = T a " (Aconc C a } = 4 2 '

These constant values are only valid, assuming the possibility oflinear interpolation between C =

amanual for DMA 4 5, i.e., DMA 4 6 ) .linear interpolation between C = 1055 and C, = 20$ (see instruction

a u

At a concentration variation of 10% there is a difference ofdensity:

As the last digit of the displayed concentration corresponds to3,2 . 10 g/cm 3 the precision of the instrument (1.10" g/cm3 )is exceeded slightly.


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DigitalDensity MetersD M AAnton PAAR KGKarntnerstrai?>e 322A-805*1Graz/AUSTRIA

MALFUNCTIONS

Causes and RemediesPlease, read instruction manual carefully

ERROR CAUSEDisplay shows The filling of the0.0000 sample tube wasnot homogeneous.

The cell selectoron the back panelwas set to "ext"and there is noexternal cellconnected.The oscillator isout of action.(T 2-B) < 0 and thebuilt-in blockingbarrier for''negative values"is not cut. Theinstrument con-stants are not setat the used meas-uring temperature.

If the concentra-tion increaseswith decreasingdensity (e.g. d i s -tilled water-alc o-hol).

Direct light isfalling on sampletube.The illuminationis turned on(switch "Light").

REMEDYA careful fillingis necessary.

Set the selectorto "i nt" or connectan external meas-uring cell.

Exchanging of theoscillator cell.All instrumentconstants are validonly for a certaintemperature. Checkif the instrumenttemperature corre-sponds to the temp-erature at whichthe apparatus con-stants are set. Atother measuringtemperatures onehas to determine newconstants B and A.Cut the wire bridgeon the left side ofthe instrument (asmall pearl marksthis wire bridge).The display willnow show the resultwithout plus orminus sign.Prevent the instru-ment from directlightSwitch off the illu-mination and wait ashort time (until astable reading isobserved).

X

X

X

DM

X

X

A

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X

50x

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X

X

X


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2ERROR

Display shows88.8888

T h i s i s ne r r o r o fs t r u m e n ti n f o r c ht h e d i s p

Display remainsat 88.8888

Display showsfluctuatingvalues

CAUSEThe measuring celldoes not oscillateor oscillates out-side the intendedfrequency range.

o t a nt h e i n -, b u t b u i l te c k i n gl a y

The filling of thesample tube wasnot homogeneous.The sample tube isnot dry enough.

The oscillator isout of action.The cell selectoron the back panelwas set to "ext"and there is noexternal cell con-nected.The filling of thesample tube wasperformed too fastand there canexist small, eveninvisible air bub-bles in the cell.The water valuescatters more thanone digit in thelast figure, al-though there seemsto be a good tern -perature equilibri-um.

REMEDYChecking of the dis-play: The display88.8888 allows theexamination of func-tion of all displayelements (of all7 segments from theL.E.D.).It is visible atonce after switchingon the instrument anddisappears within afew seconds when theoscillator works withthe intended frequency.A careful filling isnecessaryContinue the flow ofair until the dis-played value repeatsitself severaltimes.Exchanging of theoscillator cell.Set the selector to"int"or connect anexternal measuringcell.

The filling of thesample tube hasto be done slowlyand continuously(no air bubbles inthe plastic tippedsyringe )The thermostati-sation has to beperformed verycarefullyCheck as follows:Fill the sampletube with carbon te-trachloride C Olj..If there is anapprox.ten timeshigher deviation,the thermostati-sation is not suf-ficient .

40

X

X

D M45

X

X

X

X

X

X

X

A46

X

X

X

X

X

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X

50

X

X


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3ERROR

Display showsdriftingvalues.

Display showsafter measure-ment anotherT-value of airthan beforethis measure-ment .Display fluc-tuates depend-ing from day-time

Measuring val-ues do notcorrespondwith tablevalues .

CAUSEThe flow rate istoo large.

Discontinuous flowrate.

The instrumentworks under heavyvibrations.The temperatureequilibrium is notreached..Gas bubbles are inthe sample.

Solid particles maybe included in theliquid.The illumination isturned on.

There are residuesin the sample tube.

The fluctuation ofsurrounding t e m -perature influencesthe measurement.

a)Do not confusedensity units(e.g.,density-specificgravity).b)By measuring thedensity differ-ent calibrationsubstances Xden-sity standards)are used; e.g.,distilled water-city water

REMEDYBe aware for themaximum and conti-nuous flow rateDo not use pistonpump; preventcavitationWe advise shockobsorbed instal-lation.Wait until theexpected tempera-ture is reachedRemove gas fromsample (by meansof,for instance,vacuum or ultra-sonics) .Measure incontinuous flow

Switch off the illu-mination and wait ashort time (until astable reading isobserved).Repeat the cleaningand drying of thesample tube.

Do not place theinstrument in frontof radiato rs, venti-lators and preventit from direct sun-light.

O b s e r v edensity standardsand the usedmeasuring system

x

X

X

X

X

X

X

X

X

X

D M15

X

X

X

X

X

X

X

X

X

X

A46

X

X

X

X

X

X

X

X

X

X

50X

X

X

X

X

X

X

X

X


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ERROR CAUSE REMEDY D M A

Measuring val-ues are wrong.

The concentra-tion displaychanges inter-mittently .

The analogoutput remainsat a fixedvalue.

The measuring tern -perature is not thesame as used atdetermining theapparatus con-stants .A non-correspondingcalibration sub-stance was used.

There is a non-linear density-concentration de-pendenceThe accuracy (ref-erring to the den-sity) is exceeded.

If the difference(T-T Q) is too high.

T ha n is is noe r r o r

The constants arevalid only forone temperature

Concentration meas-urements are validonly for the usedcalibration sub-stance (check withwater or this cali-bration substance).Use a correspondingsmall measuringrange for a certaincalibration.A revision must beperformed).

By means of theselector switch "N"(divider)-on theback panel of theinstrument - theintended and correctrange is selected.T - T

< 256

P a r t i c u l a r a t t e n t i o n

is required when filling the samule tube (oscillator). Use plastictipped hypodermic syringesIn order to prevent a direct contact with the glass oscillatorwe recommend the use of an adapter for pressure (Cat.No . 52102),which is delivered for continuous flow measurement.In order to guarantee precise measurements place the DMA instrumentsuch, that no shoc ks, vibrations or direct sunlight affect themeasurement

antonpaar dma density meter manual

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