Metrohm 791VA User Manual
791 VA Detector
Manual
8.791.1013
Metrohm AG
CH-9101 Herisau
Switzerland
Phone +41 71 353 85 85
Fax +41 71 353 89 01
info@metrohm.com
www.metrohm.com
791 VA Detector
Manual
8.791.1013 01.2006 chs
Teachware
Metrohm AG
CH-9101 Herisau
teachware@metrohm.com
This documentation is protected by copyright. All rights reserved.
Although all the information given in this documentation has been
checked with great care, errors cannot be entirely excluded. Should you
notice any mistakes please send us your comments using the address
given above.
Documentation in additional languages can be found on
http://products.metrohm.com under Literature/Technical documenta-
tion.
Table of contents
Table of contents
1 Introduction ........................................................................................... 1
1.1 Instrument description .............................................................................1
1.2 Parts and controls.....................................................................................2
1.3 Information on the Instructions for Use ................................................4
1.3.1 Organization ..................................................................................4
1.3.2 Notation and pictograms ..............................................................5
1.4 Safety notes................................................................................................6
1.4.1 Electrical safety..............................................................................6
1.4.2 General precautionary rules..........................................................6
2 Installation.............................................................................................. 7
2.1 Setting up the instrument.........................................................................7
2.1.1 Packaging......................................................................................7
2.1.2 Check ............................................................................................7
2.1.3 Location.........................................................................................7
2.1.4 Arrangement of the instruments....................................................7
2.2 Mains connection ......................................................................................8
2.2.1 Setting the mains voltage.............................................................. 8
2.2.2 Fuses ............................................................................................. 9
2.2.3 Mains cable and mains connection .............................................. 9
2.2.4 Switching the instrument on/off.....................................................9
2.3 656 Electrochemical detector................................................................10
2.3.1 Installation and startup ................................................................10
2.3.2 Connection to 791 VA Detector...................................................10
2.4 6.5303.030 ELCD cell for IC...................................................................11
2.4.1 Assembling the ELCD cell...........................................................11
2.4.2 Connection to 791 VA Detector...................................................13
2.5 Analog output connections ...................................................................14
791 VA Detector
3 Operation...............................................................................................15
3.1 Electrochemical detection .....................................................................15
3.1.1 Classes of substances which can be determined...................... 15
3.1.2 Influence on detector signal........................................................16
3.1.3 Selection of polarization voltage .................................................17
3.1.4 Procedure for unknown substances ...........................................17
3.1.5 Practical information about ELCD...............................................18
3.2 Electrodes.................................................................................................20
3.2.1 Working electrodes .....................................................................20
3.2.2 Reference electrode ....................................................................22
3.2.3 Auxiliary electrode .......................................................................22
3.3 Operating element functions.................................................................23
3.4 Startup.......................................................................................................26
3.4.1 Preparing the ELCD cell..............................................................26
3.4.2 Zero balancing and equilibration phase .....................................27
3.4.3 Measuring procedure..................................................................29
I
Table of contents
4 Maintenance – Malfunctions.......................................... 31
4.1 Maintenance and servicing ...................................................................31
4.2 Shutdown..................................................................................................31
4.3 Malfunctions and their rectification .....................................................32
4.4 Instrument test with the dummy cell.................................................... 34
4.4.1 Check of "meas" and "damp" commutators and
of current amplifier offset ............................................................34
4.4.2 Check output voltage.................................................................. 35
4.4.3 Check of current compensation .................................................36
4.4.4 Check of current and voltage overload ...................................... 38
4.4.5 Check sensitivity knob
4.4.6 Check of noise from current amplifier......................................... 40
8 ............................................................. 39
5 Appendix................................................................................................. 41
5.1 Technical data..........................................................................................41
5.2 Standard equipment ...............................................................................43
5.2.1 2.791.0010 VA Detector for HPLC .............................................. 43
5.2.2 2.791.0020 VA Detector for IC ....................................................44
5.3 Optional accessories.............................................................................. 45
5.4 Warranty and conformity .......................................................................46
5.4.1 Warranty ......................................................................................46
5.4.2 EU Declaration of conformity ...................................................... 47
5.4.3 Certificate of conformity and system validation.......................... 48
5.5 Index..........................................................................................................49
List of figures
Fig. 1: Front of the 791 VA Detector ............................................................................. 2
: Rear of the 791 VA Detector.............................................................................. 3
Fig. 2
Fig. 3
: Setting the mains voltage.................................................................................. 9
Fig. 4
: Connection 656 – 791 .....................................................................................10
Fig. 5
: ELCD cell assembly ........................................................................................12
Fig. 6
: Connection of ELCD cell at detector block..................................................... 13
Fig. 7
: Connection of ELCD cell at 791 VA Detector.................................................. 13
Fig. 8
: Selection of polarization voltage .....................................................................17
Fig. 9
: Circuit of 6.2813.020 Dummy Cell................................................................... 34
791 VA Detector
II
1.1 Instrument description
1 Introduction
1.1 Instrument description
The 791 VA Detector allows the use of electrochemical/amperometric
detection in IC and HPLC; various working electrodes are available depending on the application. It can be used in series with another detector (e.g. 732 Conductivity detector) or simply as a «stand alone» detector.
The self-ventilating measuring cell functions according to the timeproved wall-jet principle with three-electrode technology. A silver/silver
chloride system is used as the reference electrode and a solid gold pin
as the auxiliary electrode. The carbon paste electrode and the silver
electrode have proved to be the best working electrodes; but other
electrode materials such as glassy carbon, gold, platinum and impregnated graphite are available for special applications.
The 791 VA Detector is available in the two following versions:
• 2.791.0010 VA Detector for HPLC
The measuring cell is built into the 656 Electro chemical detector.
• 2.791.0020 VA Detector for IC
The measuring cell belongs to the accessories and
is built into the 733 IC Separation Center.
791 VA Detector
1
1 Introduction
1.2 Parts and controls
13
2 4567
VA Detector791
I
comp
0.02 nA
+
~
+
overload meas
015
U
pol
10 mV
I
0.01
comp
x5damp
.
I
nAx50
50
10
0,5
0,1
5
1
Met rohm
I
(U = 1 V)
out
µ
0,1
0,5
1
5
100
10
A
4
11 89
Fig. 1
Mains pilot lamp
1
Lit up when instrument switched
: Front of the 791 VA Detector
10
7 Commutator
Changing the polarity of I
on
2 Overload display 8 Adjusting knob
Setting the current measuring sensitivity
3 Commutator
Changeover Stand-by/Measure
4 Commutator
Switching on/off damping
5 Commutator
Switching on/off multiplication of
by a factor of 5
I
comp
9 Potentiometer
Setting the absolute compensation
current I
comp
10 Potentiometer
Setting the relative compensation
current I
comp
11 Digital switch
Setting the polarization voltage
comp
6 Commutator
Switching on/off multiplication of
by a factor of 50
I
comp
791 VA Detector
2
1.2 Parts and controls
12
151413
Type 1.791.0010
f = 50-60 Hz Made by Metrohm Herisau Switzerland
S = 5 VA
Fuse
100-240 V: 1A(T)
WARNING - Fire Hazard -
For continued protection replace only
with the same type and rating of fuse
pilot
voltage
Nr.
16 17 18 19
AE RE WE shield
output 0...1 V
com 0...10 mV
Fuse holder
12
changing the fuses, see section 2.2
26 20
25
Fig. 2
: Rear of the 791 VA Detector
20 Selector
Selection of polarity for analog
output
13 Mains voltage indicator 21 Selector
Selection of full-scale deflection for
analog output
14 Earthing socket 22 Analog output (live)
15 Connection AE
23 Analog output (common)
Connection of auxiliary electrode
16 Serial number 24 Pilot voltage
Input for external voltage input for
potentiostat control
17 Connection RE
Connection of reference electrode
25 Mains switch
To switch instrument on/off:
I = ON 0 = OFF
21222324
18 Connection WE
26 Mains connection plug
Connection of working electrode
19 Connection for protective screen
791 VA Detector
Mains connection, see section 2.2
3
1 Introduction
1.3 Information on the Instructions for Use
Please read through these Instructions for Use carefully before you put
the 791 VA Detector into operation. The Instructions for Use contain
information and warnings to which the user must pay attention in order
to assure safe operation of the instrument.
1.3.1 Organization
These 8.791.1013 Instructions for Use for the 791 VA Detector provide a comprehensive overview of the installation, startup procedure,
operation, fault rectification and technical specifications of this instrument. The Instructions for Use are organized as follows:
Section 1 Introduction
General description of instrument, parts and controls
and safety notes
Section 2 Installation
Installation of accessories, connection to IC system
Section 3 Operation
Electrodes, operating element functions,
startup
Section 4 Maintenance – Faults
Maintenance, fault rectification
Section 6 Appendix
Technical data, standard equipment, options, warranty,
declarations of conformity, index
To find the required information on the instruments you will find it an
advantage to use either the Table of contents or the Index at the
back.
791 VA Detector
4
1.3 Information on the Instructions for Use
1.3.2 Notation and pictograms
The following notations and pictograms (symbols) are used in these Instructions for Use:
15 Part or control of 791
Hazard
This symbol draws attention to a
possible danger to life or of injury if
the associated directions are not
followed correctly.
Warning
This symbol draws attention to
possible damage to instruments or
instrument parts if the associated
directions are not followed correctly.
Caution
This symbol marks important
information. First read the associated directions before you continue.
Comment
This symbol marks additional
information and tips.
791 VA Detector
5
1 Introduction
1.4 Safety notes
1.4.1 Electrical safety
While electrical safety in the handling of the 791 VA Detector is assured
in the context of the specifications IEC 1010-1 (protection class 1, degree of protection IP40), the following points should be noted:
• Mains connection
Setting of the mains voltage, checking the mains fuse and the
mains connection must be effected in accordance with the instruc-
tions in section 2.2.
• Opening the 791 VA Detector
If the 791 VA Detector is connected to the power supply, the instrument must not be opened nor must parts be removed from it, otherwise there is a danger of coming into contact with components which
are live. Hence, always disconnect the instrument from all voltage
sources before you open it and ensure that the mains cable is
disconnected from mains connection 26 !
• Protection against static charges
Electronic components are sensitive to static charging and can be
destroyed by discharges. Before you touch any of the components
inside the 791 VA Detector, you should earth yourself and any tools
you are using by touching an earthed object (e.g. housing of the
instrument or a radiator) to eliminate any static charges which exist.
1.4.2 General precautionary rules
• Handling of solvents
Check all lines periodically for possible leaks. Follow the relevant
instructions regarding the handling of flammable and/or toxic solvents
and their disposal.
791 VA Detector
6
2.1 Setting up the instrument
2 Installation
2.1 Setting up the instrument
2.1.1 Packaging
The 791 VA Detector is supplied together with the separately packed
accessories in special packagings containing shock-absorbing foam
linings designed to provide excellent protection. The instrument itself is
packed in an evacuated polyethylene bag to prevent the ingress of
dust. Please store all these special packagings as only they assure
transport of the instrument free from damage.
2.1.2 Check
After receipt, immediately check whether the shipment is complete and
has arrived without damage (compare with delivery note and list of
accessories in section 5.2). In the case of transport damage, see
instructions in section 5.4.1 "Warranty".
2.1.3 Location
Position the instrument in the laboratory at a location convenient for
operation, free from vibrations and protected against a corrosive
atmosphere and contamination by chemicals.
2.1.4 Arrangement of the instruments
The 791 VA Detector can be placed on the 732 IC Detector or the 733
IC Separation Center.
791 VA Detector
7
2 Installation
2.2 Mains connection
Follow the instructions below for connecting to the power supply. If
the instrument is operated with a mains voltage set wrongly and/or
wrong mains fuse, there is a danger of fire!
2.2.1 Setting the mains voltage
Before switching on the 791 VA Detector for the first time, check that the
mains voltage set on the instrument (see Fig. 3) matches the local
mains voltage. If this is not
on the instrument as follows:
the case, you must reset the mains voltage
1 Disconnect mains cable
Disconnect mains cable from mains connection plug 26 of the
791 VA Detector.
2 Remove fuse holder
Using a screwdriver, loosen fuse holder 12 and take out completely.
3 Change mains voltage
Completely remove voltage selection insert 13 by hand, rotate it
through 180° and reinsert it. The required mains voltage (115 or
230 V) must now be visible from the front.
4 Check fuses
Carefully take both fuses out of fuse holder 12 and check their
specifications:
100…240 V 1 A (slow-blow) Metrohm-No. U.600.0016
5 Insert fuses
Change both fuses if necessary and reinsert in fuse holder 12.
6 Install fuse holder
Push fuse holder 12 back into the opening of 791 VA Detector
by hand until it clicks into place properly.
791 VA Detector
8
2.2 Mains connection
100 – 120 V220 – 240 V
13
12
230
115
12 Fuse holder
13 Voltage selection
insert with display
of voltage
25
26
Fig. 3
: Setting the mains voltage
2.2.2 Fuses
Two fuses 1 A/slow-blow for 100…240 V are installed in the fuse holder
12 of the 791 VA Detector as standard.
Ensure that the instrument is never put into operation with fuses of
another type, otherwise there is danger of fire!
For checking or changing fuses, proceed as described in section 2.2.1.
2.2.3 Mains cable and mains connection
Mains cable
The instrument is supplied with one of three mains cables
25 Mains switch
26 Mains connection
plug
• 6.2122.020 with plug SEV 12 (Switzerland, …)
• 6.2122.040 with plug CEE(7), VII (Germany, …)
• 6.2133.070 with plug NEMA 5-15 (USA, …)
which are three-cored and fitted with a plug with an earthing pin. If a different plug has to be fitted, the yellow/green lead (IEC standard) must
be connected to protective earth (protection class 1).
Any break in the earthing inside or outside the instrument can make it
a hazard!
Mains connection
Plug the mains cable into mains connection plug 26 of the 791 VA Detector (see Fig. 3).
2.2.4 Switching the instrument on/off
The 791 VA Detector is switched on and off using mains switch 25.
When the instrument is switched on lamp 1 lights up.
791 VA Detector
9
2 Installation
2.3 656 Electrochemical detector
2.3.1 Installation and startup
Inserting the detector cell in shield housing, fitting the electrodes and
startup of the 656 Electrochemical detector (order number 2.656.0020)
are described in detail in the 656 Instructions for use.
2.3.2 Connection to 791 VA Detector
The electrodes used in the detector cell are each connected to the corresponding connection of the 791 VA Detector with a 6.2120.020 Electrode cable as shown in Fig. 4. In addition the two earthing sockets are
connected with a 6.2106.020 Cable.
6.2120.0 20 6.2106.0 20
656
AE WE RE
Fig. 4
AE RE WE
: Connection 656 – 791
791
791 VA Detector
10
2.4 6.5303.030 ELCD cell for IC
2.4 6.5303.030 ELCD cell for IC
2.4.1 Assembling the ELCD cell
The reference electrode and working electrode must be inserted in the
6.5303.030 ELCD Cell supplied with the 2.791.0020 VA Detector. The
cell is then screwed into the detector block built into the 733 IC Separation Center. Proceed as follows (see Fig. 5 and Fig. 6):
1 Insert reference electrode
Reference electrode 39 (6.0727.000, details see section 3.2.2)
included in the supply is already filled with c(KCl) = 3 mol/L and
protected with a cap. It is assembled as follows (see Fig. 5):
• Screw off the cap of electrolyte storage vessel 41 of reference
electrode 39. Normally PTFE gasket 31 remains in the cap
and can be left there.
• Insert one of the supplied PTFE gaskets 31 into the corre-
sponding opening of cell body 32 and screw reference electrode 39 into this opening.
2 Insert working electrode
Working electrode 28 is not supplied with the 791 VA Detector
and must be ordered separately. Details about the working
electrodes and information about pretreatment (e.g. polishing)
can be found in section 3.2.1. A working electrode is assembled
as follows (see Fig. 5):
• Insert working electrode 28 in screw nipple 29.
• Push one of the supplied PTFE gaskets 31 sufficiently far
along the working electrode from below.
• Carefully insert working electrode 28 into the corresponding
opening of cell body 32 from above and press it in until it
clearly clicks into position.
• Push screw nipple 29 downwards and screw it in.
3 Connect ELCD cell to the detector block
The ELCD cell is screwed onto the 1.733.0X10 Detector block
mounted inside the 733 Separation Center. Proceed as follows
(see Fig. 5 and Fig. 6):
• Screw cell body 32 onto detector block 42 with the help of
the two red knurled screws 43.
• Push one of the supplied PTFE gaskets 31 over screw nipple
33 and screw this into the corresponding opening of cell
body 32.
• Place a screw nipple 36 and a PTFE gasket 35 on the outlet
end of the outlet capillary 37 permanently connected to detector block 42.
• Insert outlet capillary 37 with screw nipple 36 in place into
screw nipple 33 and press in outlet capillary 37 until it
reaches the stop.
791 VA Detector
11
Loading...