Metrohm 776 Dosimat User manual

CH-9101 Herisau/Switzerland
Tel. [phone]
Fax [phone]
E-Mail [email protected]
Internet http://www.metrohm.ch
776 Dosimat
Instructions for Use
8.776.1023
2005.06 ti/dm

Content
776 Dosimat
Content
1 Overview ...................................................................................................................2
2 Operation with the keyboard ...................................................................................4
2.1 Keypad........................................................................................................................4
2.1.1 Key <RATE> .......................................................................................................6
2.2 Modes ......................................................................................................................... 6
2.2.1 Mode DOS, dosing .............................................................................................. 7
2.2.2 Mode DIS R, repetitive dispensing....................................................................... 9
2.2.3 Mode DIS C, cumulative dispensing.................................................................... 9
2.2.4 Mode PIP, pipetting............................................................................................ 10
2.2.5 Mode DIL, diluting..............................................................................................11
2.2.6 Mode CNT D, content dispenser ....................................................................... 12
2.3 User memory ............................................................................................................17
2.4 Special settings.........................................................................................................18
3 Error messages, troubleshooting..........................................................................19
3.1 Special messages and error messages ................................................................... 19
3.2 Diagnosis ................................................................................................................. 21
3.3 RAM initialisation....................................................................................................... 29
3.4 Releasing a locked spindle with insertd Exchange Unit...........................................30
4 Appendix.................................................................................................................31
4.1 Technical specifications............................................................................................ 31
4.2 Warranty and certificates .......................................................................................... 33
4.2.1 Warranty .............................................................................................................33
4.2.2 Certificate of Conformity and System Validation................................................ 34
4.3 Scope of delivery and ordering designations ........................................................... 36
Index...........................................................................................................................37

Overview
776 Dosimat
1
Explanation of symbols:
< > means "key", e.g. <GO> means key "GO"
DOS.....0.000 ml means "display"

Overview
776 Dosimat
2
1 Overview
Front view of instrument:
1 Exchange unit
Normally the models with automatic cock changeover.
Note:
Choose the volume of the Exchange unit in such a way that a volume between
10...100% of the nominal volume is expelled.
2 Display
The 16 digit display shows all important information:
DOS 3.456 ml Mode (DOS = dosing) and dosed volume. Dosimat is in
stand-by position
DOS ↑3.456 ml The piston is moving upwards.
DOS ↓3.456 ml The piston is moving downwards.
DOS →3.456 ml The cock is turned to the right.
DOS ←3.456 ml The cock is turned to the left.
The display of the status ↑resp.↓are specially important for very slow dosings
where movements of the piston cannot be clearly identified.
3 Operating keys at the Dosimat
<FILL> Filling. This key is always accessible and serves also as
emergency stop.
<CLEAR> Resetting of the volume display to 0 with Dosimat in stand-by
position.
<GO> Order to execute the current mode. With mode DOS, dosing
goes on as long as <GO> is pressed.
4 Setting of display contrast
5 Analogue setting of dosing rate
Position 1 = lowest rate
Position 10 = highest rate
The expelling and filling rates can be set separately (see page 6).

Overview
776 Dosimat
3
Rear view of instrument:
6 Connection for keyboard
For details of operation with keyboard 6.2149.000 see page 4ff.
7 Power connection
In power supply systems, in which strong HF interferences (transients) are su-
perimposed on the power voltage, the 776 Dosimat should be connected via an
additional power line filter, e.g. METROHM 615 model.
The main cables supplied with the instrument are three-core and equipped with
a plug with an earthing pin. If a different plug has to be fitted, the yellow/green
lead must be connected to the protective earth. Each break in the earthing inside
or outside the instrument can make it a hazard.
When the instrument is opened or if parts of it are removed, certain components
may be live if the instrument is connected to the power line. The power cable
must therefore always be unplugged when certain adjustments are made or
parts replaced.
8 Power switch
Switching on and off Dosimat. The 776 Dosimat is equipped with a non-volatile
memory, i.e. set parameters remain in the working memory if the Dosimat is
switched off and on.
9 Earthing socket
The 776 Dosimat must be grounded correctly and effectively, if necessary
through the separate earthing socket.
10 Connection for stirrer
In general a Magnetic Stirrer (forms a complete titrating stand). Other stirrers
may be connected as well, e.g. a METROHM Rod Stirrer. Supply voltage output:
+9 V DC (I#200 mA).
11 Connection for external dosing contact
E.g. 6.2107.000 push button cable.
12 Indication of power voltage
Make sure the current has been adapted correctly before Dosimat is switched
on.
13 Identification plate
Indication of model, series and serial number.

2.1. Keypad
776 Dosimat
4
2 Operation with the keyboard
2.1 Keypad
6.2149.000
SMPL
9
BLANK
7
FACTOR
8
RATE VOLUME EXP
ENTER
FILL GOCLEAR
RECALL
6
STORE
5
UNIT
4
3
2
1
MODE
–
.
0
RATE Expelling and filling rate in all modes.
VOLUME Different volumes depending on selected
mode.
EXP Exponent.
BLANK
FACTOR Calculation parameters in mode DOS.
SMPL
UNIT Unit in modes DOS and CNT
STORE Management of user memory:
RECALL Storing, loading of modes.
MODE Selection of mode.
ENTER Confirmation of entries.
FILL Filling and emergency stop key.
CLEAR Resetting of the volume display to 0 with
Dosimat in stand-by position.
GO Start mode. With mode DOS, dosing
goes on as long as <GO> is pressed.
The keys <FILL>, <CLEAR>, <GO> are identical
with the corresponding keys on Dosimat.

2.1 Keypad
776 Dosimat
5
Rules for data input:
• On entering a negative number, key in minus sign first; <-> is not a "change of sign"
key!
• Changeover between first functions (blank, factor etc.) and digits is done
automatically.
• Terminate parameter entries with <ENTER>.
• Some keys are organized as inquiry drums, i.e. pressing these keys several times, dis-
play shows new inquiries. A new value is stored or a new feature is selected with
<ENTER>. The program then returns to the initial state, the inquiry drum is left. Enter-
ing an inquiry drum, that inquiry, where the drum has been left last time, is displayed
first.
• The Dosimat works with a resolution of 10'000 pulses per burette cylinder volume. The
resolution on the display is therefore depending on the mounted Exchange unit.
Exchange unit Resolution of display
Volume/mL Rate mL/min
Smallest increment
V
1 mL .001 .001 0.1 µL
5 mL .001 .005 0.5 µL
10 mL .001 .010 1 µL
20 mL .002 .020 2 µL
50 mL .005 .050 5 µL
If a volume value is entered which can not be dosed exactly with the Exchange unit
mounted, the value is rounded off to the next possible one and stored accordingly.
• Key <CLEAR> sets parameters to "OFF".

2.2. Modes
776 Dosimat
6
2.1.1 Key <RATE>
The inquiries of this key are identical for all modes.
Expelling and filling rate
This key is accessible live (except in mode DOS), i.e. rate can be
changed during a running function .
↑ml/min
Expelling rate
Range for digital setting depending on volume of Exchange unit:
1 mL 0.001 3.00 mL/min
5 mL 0.005 15.0 mL/min
10 mL 0.010 30.0 mL/min
20 mL 0.020 60.0 mL/min
50 mL 0.050 150.0 mL/min
Key <CLEAR> sets "OFF", i.e.. the rate can be controlled
analogically by means of potentiometer at the Dosimat 776.
If the preset rate is too high to be dosed with the Exchange unit
presently mounted, the rate is set automatically to its maximum.
↓ml/min Filling or aspirating rate
The data input rules are the same as for the expelling rate.
The filling rate is set to maximum on changing the Exchange unit
(e.g. always after no exch. unit! is displayed!).
2.2 Modes
The modes are selected by the inquiry drum <MODE> and
confirmed with <ENTER>.
DOS: DOSing
Dosimat is dosing as long as <GO> is pressed. Result calculation
can be activated.
DIS R: DISpensing, Repetitive
Dosimat is dosing a stored dispensing volume if <GO> is pressed,
the burette cylinder is refilled and display reset to 0.000 mL.
DIS C: DISpensing, Cumulative
Dosimat is dosing a stored dispensing volume if <GO> is pressed,
the dispensed volume (V-DIS) remains displayed.
PIP: PIPetting
Aspirating and subsequent expelling of a stored pipetting volume.
DIL: DILuting
Aspirating a stored pipetting volume and subsequent expelling of the
pipetting and diluting volume.
CNT D: CoNTent Dispenser
Preparation of solutions with preselected content.
RATE
MODE

2.2 Modes
776 Dosimat
7
Example:
Selection of mode "DIS C", cumulative dispensing.
Press <MODE>.
Display shows that mode which has been selected last with key <MODE>, e.g.
DOS .
Press <MODE> repeatedly until display shows DIS C .
Load mode "DIS C" into working memory with <ENTER>.
Display shows DIS C 0.000 ml.
Mode "DIS C" is ready to work, the piston is in zero position.
All modes which are loaded into the working memory by key <MODE> are equipped
with a set of standard parameters:
Mode V-DIS/V-PIP
mL
V-LIM/V-DIL
mL
Rate ↑
mL/min
Rate ↓
mL/min
Calculation
DOS – OFF OFF max. b=0; f=1; s=1
DIS R 1 – OFF max. –
DIS C 0.1 OFF OFF max. –
PIP 0.1 – OFF OFF –
DIL 0.1 1 OFF OFF –
CNT D – – OFF max. –
2.2.1 Mode DOS, Dosing
Dosimat is dosing as long as <GO> is pressed. Result calculation can be activated.
V-LIM OFF ml
Security volume:
Dosing is stopped if V-LIM has been reached.
Input range: 0.001...999.999 mL, OFF
Expelling and filling rate, see page 6.
VOLUME
RATE

2.2. Modes
776 Dosimat
8
Calculation values
b = 0. ml
Blank value
Input range: 0...±999.999 mL
f = 1.
Factor
Input range: 0... ±1E33
s = 1.
Sample size
Input range: 0... ±1E33
unit
Unit
Input range: ppm, %, g, mg, g/L, mg/L, mol, mol/L, mL, L,
/pc, none
Result calculation
If one of the calculation values (blank, factor, smpl) is not set to its standard value, a
result is calculated on filling of the Dosimat according to formula:
(dosed volume – blank)*factor
Result = ————————————————
smpl
The result is recalculated on each entry of a calculation value (blank, factor, smpl).
Pressing <CLEAR> display shows the dosed volume in mL. To start a new dosing, press
<GO> twice, pressing once resets the volume in display to 0.000 mL.
7
BLANK
SMPL
8
FACTOR
UNIT
9
4

2.2 Modes
776 Dosimat
9
2.2.2 Mode DIS R, Repetitive Dispensing
Dosimat is dosing a stored dispensing volume if <GO> is pressed. The burette cylinder
is refilled and display reset to 0.000 mL.
V-DIS 1. ml
Dispensing volume
Input range: 0.001...999.999 mL
Expelling and filling rate, see page 6.
2.2.3 Mode DIS C, Cumulative Dispensing
Dosimat is dosing a stored dispensing volume if <GO> is pressed, and the dispensed
volume (V–DIS) remains displayed.
V-DIS 0.1 ml
V-LIM OFF ml
Dispensing volume
Input range: 0.001...999.999 mL
Security volume
Dispensing is stopped, if V-LIM has been reached.
Input range: 0.001...999.999 mL, OFF
Expelling and filling rate, see page 6.
VOLUME
RATE
VOLUME
RATE

2.2. Modes
776 Dosimat
10
2.2.4 Mode PIP, Pipetting
Aspirating and subsequent expelling of a stored pipetting volume.
V-PIP 0.1 ml
Pipetting volume
Input range depends on the volume of the Exchange unit:
1 mL 0.001... 0.900 mL
5 mL 0.001... 4.900 mL
10 mL 0.001... 9.800 mL
20 mL 0.002... 19.700 mL
50 mL 0.005... 49.500 mL
Note: The liquid of the Exchange unit is mixed with the
pipetted liquid if it is aspirated into the burette cylinder!
The aspiration tube must contain V-PIP!
Expelling and filling rate see page 6.
If mode PIP is loaded, the display shows PIP * 0.000 ml.
The sign * in the display means that mode "PIP" is not yet ready to be used. With a first
<GO>, a preparation step is carried out which is marked in the display with
PIP prep. . This preparation step includes the formation of an air bubble which
serves to separate the transfer solution of the Exchange unit from the sample.
Then display shows PIP 1 0.100 ml, i.e. the Dosimat is ready to aspirate the pipetting
volume (0.1 mL). With <GO> the pipetting volume is aspirated and display shows
PIP 2 0.100 ml which means that the Dosimat is ready to expel the pipetting volume.
With the next <GO>, the volume is expelled and the Dosimat is then ready to aspirate
the next pipetting volume without any preparation step.
If the pipetting volume is changed, a new preparation step is always carried out.
Sequence of PIP
Standard mode PIP.
Preparation step: Hold burette tip free at working
height.
Ready to aspirate the pipetting volume: Immerse
burette tip.
Ready to expel the pipetting volume: Hold
burette tip for pipetting.
VOLUME
RATE
PIP * 0.000 ml
↓
<GO>
↓
PIP prep.
↓
PIP 1 0.100 ml
↓
<GO>
↓
PIP 2 0.100 ml
↓
<GO>
↓

2.2 Modes
776 Dosimat
11
Note
• A new air bubble is built with every preparation step ("prep.") e.g. its volume increases.
If you wish to keep the volume of the air bubble expel it in mode DOS before changing
V-PIP.
• For best pipetting results we recommend Exchange units with volumes ≤20 mL and
pipetting equipment 6.5611.000.
• The aspirating and expelling rates should not be higher than 20 mL/min.
• Hold tubing tip in an angle of app. 45°to the vessel wall during pipetting. Just the
same as you do with glass pipettes!
• The vessel, containing the liquid you want to pipette should stand on the same level as
the vessel into which you are going to expel the liquid in order to ascertain app. the
same level of the pipetting tubing during work.
2.2.5 Mode DIL, Diluting
Aspirating a stored pipetting volume and subsequent expelling of the pipetting and dilut-
ing volume.
V-PIP 0.1 ml
V-DIL 1. ml
Pipetting volume
Input range depends on the volume of the Exchange unit:
1 mL 0.001... 0.900 mL
5 mL 0.001... 4.900 mL
10 mL 0.001... 9.800 mL
20 mL 0.002... 19.700 mL
50 mL 0.005... 49.500 mL
Diluting volume
Input range: 0.001...999.999 mL
Note: The diluting liquid is unintentionally mixed with the
pipetted liquid if it is aspirated into the burette cylinder!
The aspiration tube must contain V-PIP!
Expelling and filling rate see page 6.
If mode DIL is loaded, the display shows DIL * 0.000 ml.
The sign * in the display tells you that mode DIL is not ready to be used. With <GO> a
preparation step is carried out during which V-PIP is expelled into the bottle of the
Exchange unit and an air bubble is built to separate the solution of the Exchange unit
from the sample.
Then the Dosimat is ready to aspirate the pipetting volume (0.1 mL) which is displayed by
DIL 1 0.100 ml and carried out after pressing <GO>.
Then DIL 2 1.100 ml is displayed which means that the Dosimat is ready to expel the
pipetting and the diluting volume (0.1 mL + 1 mL = 1.1 mL). This is executed after
<GO>. The preparation step is now carried out automatically and the Dosimat is ready to
aspirate the next pipetting volume.
VOLUME
RATE

2.2. Modes
776 Dosimat
12
Sequence of DIL
Standard mode DIL.
Preparation step: Hold burette tip free at working
height.
Ready to aspirate the pipetting volume: Immerse
burette tip.
Ready to expel the pipetting and diluting volume:
Hold burette tip for pipetting.
Notes
• If you wish to change V-PIP, it is best to change it during filling in the preparation step,
i.e. when display shows DIL ↓prep..
• If V-PIP is changed at another time, a new preparation step is carried out, which
changes the volume of the air bubble. The first dilution after such a change could be
erroneous and should be discarded. Another possibility is to expel the air bubble in
mode DOS and to start Mode DIL from the beginning. V-DIL can be changed at any
time without a new preparation step.
2.2.6 Mode CNT D, Content Dispenser
Mode CNT D is used to prepare solutions with a particular content. Doing this, the sub-
stance must not be weighed-out to a particular value in order to obtain the preselected
content but the 776 Dosimat dispenses the amount of solvent calculated correspond-
ingly.
Expelling and filling rate see page 6.
RATE
DIL * 0.000 ml
↓
<GO>
↓
DIL prep.
↓
DIL 1 0.100 ml
↓
<GO>
↓
DIL 2 1.100 ml
↓
<GO>
↓
DIL prep.
↓

2.2 Modes
776 Dosimat
13
Content entries which can be implemented in the CNT D mode are summarized below
and designated with a bold frame
Concentration Fraction Molality
Reference quantity
(denominator)
Specified
quantity
(numerator)
Volume
of the solution
V / L
Sum
of the components j
Mass
of the solvent
mk/ kg
Amount of
substance
ni/ mol
Amount of substance
concentration c
ci= ni/V
Units: mol/L, mmol/L
Example: c(NaOH)=0.1
mol/L
Outdated: molarity, molar
Amount of substance
fraction x
xi= ni/Σnj
Unit: 1
Example: x(Au)=0.005
Outdated: mole fraction, mole
percent
Molality b
bi= ni//mk
Unit: mol/kg, mmol/kg
Example: b(KOH, in EtOH) = 1
mol/kg
Mass
mi/ kg
Mass concentration ρ
ρi= mi/V
Units: g/L, mg/L
Example: ρ(Pb2+)= 1 g/L
Outdated: mg%
Mass fraction w
wi= mi/Σmj
Units: %, ppm; 1
Example: w(H2O)= 5%
Outdated: weight percent
Sequence of CNT D
Standard mode CNT D. Display changes
automatically after preparation.
Choose unit by pressing key <UNIT>.
The volume is calculated according to the
chosen unit.
Input of the desired numerical value for the
content.
Depending on the unit selected the following
auxiliary variables are inquired during the first
run:
M 1 g/mol Molar mass of the substance
dens. 1 g/ml Density of the solvent
f 1.00000 Factor for volume contraction
Input of the weight.
The calculated volume is displayed and expelled
with <GO>.
With <CLEAR> the values for "cnt" and/or "s" can
be changed. This gives an idea of the
approximate weighing.
Pressing <MODE>, the mode can be changed.
CNT D 0.000 ml
↓
unit %
↓
↓
<ENTER>
↓
cnt 1 %
↓
Input <ENTER>
↓
↓
↓
↓
↓
↓
s 1 g
↓
Input <ENTER>
↓
add V XXX.XXX ml
↓↓
<GO> <CLEAR>
↓
dosing V

2.2. Modes
776 Dosimat
14
The formulae for calculation of the volume to be dispensed "add V" are shown in the
following table, with
cnt content in the selected unit
M molar mass of substance to be weighed out
f factor
dens density of the solvent
s weight of substance
Unit Formula for
add V =
Amount-of-substance
concentration
mol/L
mmol/L
f·s·103
cnt·M
f·s·106
cnt·M
Mass concentration
g/L
mg/L
f·s·103
cnt
f·s·106
cnt
Mass fraction
%
ppm
f·s(102-cnt)
cnt·dens
f·s(106-cnt)
cnt dens
Molality
mol/kg
mmol/kg
s·103
cnt·M·dens
s·106
cnt·M·dens
Application of factor f
Factor f for ionic standards
With ionic standards, the mass fraction of a single ion A is usually specified. On the other
hand, the solution is prepared from AnBm, e.g. a standard of 10 ppm Pb2+ prepared from
Pb(NO3)2. The factor f is calculated from the formula:
n*M(A) m*M(B)
f = ———— or f = ————
M(AnBm) M(AnBm)
M(A): molar mass of ion A
M(B): molar mass of ion B
M(AnBm): molar mass of substance AnBm

2.2 Modes
776 Dosimat
15
The following table shows factors for the most common ionic standards:
Cation Standard
prepared from:
Factor f Anion Standard
prepared from:
Factor f
Na+NaCl
NaNO3
0.39339
0.27050
F-NaF 0.45245
K+KCl
KNO3
0.52441
0.38670
Cl-NaCl
KCl
0.60666
0.47550
Ca2+ CaCl20.36111 Br-NaBr·2H2O
KBr
0.57514
0.67141
Ba2+ BaCl2·2H2O
Ba(NO3)2
0.56222
0.52550
I-KI 0.76444
Cu2+ Cu(ClO4)2
Cu(NO3)2·6H2O
0.24214
0.21494
SO4
2- K
2SO40.55087
Pb2+ Pb(ClO4)2·3H2O
Pb(NO3)2
0.45028
0.62557
NO3
-NaNO3
KNO3
0.72950
0.61319
PO4
3- Na2HPO4·12H2O
Na3PO4·12H2O
0.26519
0.24985
The factor f as correction for substances with admixtures
e.g. water of crystallization, impurities, moisture.
The factor f as correction for the volume contraction
For the amount-of-substance concentration c (units mol/L and mmol/L) and the mass
concentration ρ(units g/L and mg/L), the concentration is referred to the volume of the
solution.
c
i= ni/V resp. ρi= mi/V
where niamount of substance i
m
imass of substance i
V volume of the solution

2.2. Modes
776 Dosimat
16
Since the volume of the solvent V0is dispensed in the operational method of the CNT D
mode, higher concentrations require a correction factor which takes the difference
between V0and V (volume of the solution) into consideration:
V
0
f = —–
V
This factor can be determined with the Dosimat in the DOS mode:
A solution of the desired concentration is prepared in the conventional manner in a
volumetric flask by dispensing the solvent with the aid of the Dosimat up to the mark of
the flask (V0). If the volume V of the volumetric flask is inputted in the calculation
parameter "s", the factor f is calculated directly by the Dosimat and appears on the
display.
The factor f determined in this manner holds for the appropriate substance/solvent pair in
the measured concentration range with the possibility of linear extrapolations up to
concentrations of ca. 1 mol/L.
Several correction factors are shown in the following table:
Concentration c
Substance/solvent
0.05
mol/L
0.1 mol/L 1 mol/L
Potassium hydrogen
phthalate/water
0.999 0.998 0.982
Na2EDTA·2H2O/water 0.991 0.981 -
NaCl/water 0.999 0.998 0.982
KNO3/water 0.998 0.997 0.960
CuSO45H2O/water 0.995 0.992 0.904