Page 1
Digest System K�437
Operation Manual
11593500
en
Page 2
Page 3
Table of contents
3 K-437 Operation Manual, Version A
Table of contents
1 About this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 User qualification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Proper use K-437 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Proper use COD Accessory with K-437 . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4 Improper use COD Accessory with K-437. . . . . . . . . . . . . . . . . . . . . . . . 6
2.5 Warning notices used in this manual . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.6 Product safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.6.1 Instrument-related hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.6.2 Other hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.6.3 Safety measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.7 General safety rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 Scope of delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.1 Standard instrument K-437 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.2 Standard instrument COD Accessory . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1.3 Standard accessories K-437 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1.4 Standard accessories COD Accessory . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1.5 Optional accessories K-437 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2 Technical data overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Materials used. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 Description of function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1 Functional principle of the Digest System . . . . . . . . . . . . . . . . . . . . . . . 14
4.2 Functional principle of the COD Accessory . . . . . . . . . . . . . . . . . . . . . . 15
4.3 Controls of the Digest System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.4 Rear connections of the Digest System . . . . . . . . . . . . . . . . . . . . . . . . 15
5 Putting into operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.1 Installation site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.2 Electrical connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.3 Hose connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Read this manual carefully before installing and running your system and note the safety precautions
in chapter 2 in particular. Store the manual in the immediate vicinity of the instrument, so that it can be
consulted at any time.
No technical modifications may be made to the instrument without the prior written agreement of
BUCHI. Unauthorized modifications may affect the system safety or result in accidents.
This manual is copyright. Information from it may not be reproduced, distributed, or used for competitive purposes, nor made available to third parties. The manufacture of any component with the aid of
this manual without prior written agreement is also prohibited.
The English manual is the original language version and serves as basis for all translations
into other languages. If you need another language version of this manual, you can download available versions at www.buchi.com.
Page 4
Table of contents
4
K-437 Operation Manual, Version A
6 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1 General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2 Kjeldahl digestion process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.3 Operating the K-437 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.4 Service menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.1 Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.2 Glass parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.3 Digestion tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.4 Sealing system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.4.1 Cleaning the seals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.4.2 Replacing the seals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.5 Exhaust unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.6 Power supply fuse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.7 Customer service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.1 Malfunctions and their remedy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9 Shutdown, storage, transport and disposal . . . . . . . . . . . . . . . . . . . . . . . . 27
9.1 Storage and transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
9.2 Disposal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
10 Spare parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
11 Declarations and requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
11.1 FCC requirements (for USA and Canada) . . . . . . . . . . . . . . . . . . . . . . . 30
11.2 Declaration of conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Page 5
1 About this manual
5 K-437 Operation Manual, Version A
1 About this manual
This manual describes the Digest System and provides all information required for its safe operation
and to maintain it in good working order.
It is addressed to laboratory personnel in particular.
NOTE
The symbols pertaining to safety (WARNINGS and ATTENTIONS) are explained in chapter 2.
Reference documents
For information on the Digestion Unit and the Scrubber, please refer to the corresponding manuals
available in English, German, French, Italian and Spanish
Digest Automat K-432/438, Operation Manual numbers 96765 - 96769•
SpeedDigester K-425/K-436, Operation Manual numbers 11593346 - 11593350•
SpeedDigester K-439, Operation Manual numbers 11593351 - 11593355•
Scrubber•
Page 6
2 Safety
6 K-437 Operation Manual, Version A
2 Safety
This chapter points out the safety concept of the instrument and contains general rules of behavior
and warnings from hazards concerning the use of the product.
The safety of users and personnel can only be ensured if these safety instructions and the safetyrelated warnings in the individual chapters are strictly observed and followed. Therefore, the manual
must always be available to all persons performing the tasks described herein.
2.1 User qualification
The instrument may only be used by laboratory personnel and other persons who on account of
training or professional experience have an overview of the dangers which can develop when
operating the instrument.
Personnel without this training or persons who are currently being trained require careful instruction.
The present Operation Manual serves as the basis for this.
2.2 Proper use K-437
The instrument has been designed and built for laboratories. It serves for the heating of concentrated
sulphuric acid for oxidation of organic sample components.
2.3 Proper use COD Accessory with K-437
The instrument has been designed and built for laboratories. It serves for the heating of samples for a
following COD (chemical oxygen demand) determination.
2.4 Improper use COD Accessory with K-437
Applications not mentioned above are improper. Also, applications, which do not comply with the
technical data, are considered improper.
The operator bears the sole risk for any damages caused by such improper use.
The following uses are expressly forbidden:
Use of the instrument in rooms which require ex-protected instruments.•
Use on samples, which can explode or inflame (e.g. explosives, etc.) due to shock, friction, heat or •
spark formation.
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2 Safety
7 K-437 Operation Manual, Version A
2.5 Warning notices used in this manual
WARNING
Generally, the triangular warning symbol indicates the possibility of personal injury or even loss of life
if the instructions are not followed.
WARNING
Hot surface.
WARNING
Electrical hazard.
WARNING
Biohazard.
WARNING
Pinch point. Mechanical hazard.
ATTENTION
With the general “Read this” symbol, ATTENTIONs indicate the possibility of equipment damage,
malfunctions or incorrect process results, if instructions are not followed.
NOTE
Useful tips for the easy operation of the instrument.
2.6 Product safety
The Digest System is designed and built in accordance with state-of-the-art technology. Nevertheless, risks to users, property, and the environment can arise when the instrument is used carelessly or
improperly.
The manufacturer has determined residual dangers emanating from the instrument
if the instrument is operated by insufficiently trained personnel.•
if the instrument is not operated according to its proper use.•
Appropriate warnings in this manual serve to make the user alert to these residual dangers.
2.6.1 Instrument-related hazards
Pay attention to the following safety notices:
WARNING
Potential implosion risk if used with damaged glassware.
Beware of damaged or cracked glass parts.•
WARNING
Potentially hot surfaces during operation, especially at the glass parts or due to hot sulphuric acid.
Always be aware of the risk of being burned.•
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2 Safety
8 K-437 Operation Manual, Version A
WARNING
Potentially lethal voltage inside the instrument.
Do not remove covers and other parts protecting from electricity.•
Always keep the areas of electric parts, such as power supply plug, mains switch, etc. dry.•
WARNING
In order to avoid injuries to the hands and fingers the machine may not be manipulated during the
lifting action.
2.6.2 Other hazards
WARNING
Certain solvents in or in the vicinity of the Digest System can form peroxides and/or are highly inflammable.
Always be aware of the explosion risk when working with hazardous substances or with •
substances of unknown composition.
Always provide a good ventilation within or in the vicinity of the system.•
2.6.3 Safety measures
In case a safe operation of the instrument no longer appears possible, the instrument must be shut
down and secured against inintentional operation.
It must be assumed that safe operation is no longer possible:
if there is visible instrument damage,•
following a long period of storage under unfavorable conditions,•
following transport under difficult conditions.•
Always wear personal protective equipment such as protective eye goggles, protective clothing and
gloves when working with the instrument.
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2 Safety
9 K-437 Operation Manual, Version A
2.7 General safety rules
Responsibility of the operator
The head of laboratory is responsible for training his personnel.
The operator shall inform the manufacturer without delay of any safety-related incidents which might
occur during operation of the instrument. Legal regulations, such as local, state and federal laws
applying to the instrument must be strictly followed.
Duty of maintenance and care
The operator is responsible for ensuring that the instrument is operated in proper condition only, and
that maintenance, service, and repair jobs are performed with care and on schedule, and by authorized personnel only.
Spare parts to be used
Use only genuine consumables and genuine spare parts for maintenance to assure good system
performance and reliability. Any modifications to the spare parts used are only allowed with the prior
written permission of the manufacturer.
Modifications
Modifications to the instrument are only permitted after prior consultation with and with the written
approval of the manufacturer. Modifications and upgrades shall only be carried out by an authorized
BUCHI technical engineer. The manufacturer will decline any claim resulting from unauthorized modifications.
Page 10
3 Technical data
10 K-437 Operation Manual, Version A
3 Technical data
This chapter introduces the reader to the instrument specifications. It contains the scope of delivery,
technical data, requirements and performance data.
3.1 Scope of delivery
Check the scope of delivery according to the order number.
NOTE
For detailed information on the listed products, see www.buchi.com or contact your local dealer.
3.1.1 Standard instrument K-437
Table 3-1: Standard instrument
Product Order number
K-437 230 V 50/60 Hz standard 38584
K-437 230 V 50/60 Hz
with condensate trap
40316
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3 Technical data
11 K-437 Operation Manual, Version A
3.1.2 Standard instrument COD Accessory
Table 3-2: Versions of COD Accessories
Product Order number
COD Accessory for Digestion Sytem
K-437 or Digest Automat K-438
43960
Digest System K-437 with COD Accessories
43963
3.1.3 Standard accessories K-437
Table 3-3: Standard accessories K-437
Product Order number
1 suction module, complete 38561
1 rack, 20 spaces 38621
20 digestion tubes (5 x set of 4 tubes) 37377
1 EPDM hose, 1.5 m, 8 mm 11056005
1 power cable
Type CH 10021
Type Schuko 10029
Type GB 17833
Type USA 33756
Type AUS 17834
1 Operation Manual:
English 11593500
German 11593501
French 11593502
Italian 11593503
Spanish 11593504
1 packaging 35161
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3 Technical data
12 K-437 Operation Manual, Version A
3.1.4 Standard accessories COD Accessory
1
2
3
4
5
7
6
Table 3-4: Standard accessories COD Accessory
Product Order number
a Rack condenser COD 43956
b Condenser COD (set of 4) 43962
c Stand for condenser COD 43957
d Rack COD 11055195
e Digestion tubes COD (set of 4) 43961
f Preparation block COD 43953
g Digestion tube holder COD 43955
3.1.5 Optional accessories K-437
Table 3-5: Optional accessories K-437
Product Order number
Water jet pump made of plastic 02913
PTFE seal for suction tube, set of 20
sealings
38623
Retaining plate, for dishwasher 38559
Stand for racks 38639
Suction tube with condensate trap 38640
Scrubber with condenser, 230 V 37882
Connecting cable to Scrubber 30973
Air supply to external fan 40079
Drip tray 40055
Additional heating block (higher) 40088
Heat isolation cover 40052
Glass caps (4 pieces) 40049
IQ/OQ set (en) 11057092
Repeating OQ (en) 11057093
Condensate bottle 25100
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3 Technical data
13 K-437 Operation Manual, Version A
3.2 Technical data overview
Table 3-6: Technical data K-437
Digest System K-437
Dimensions (W x D x H) 435 x 560 x 780 mm
Connection voltage 200-230 V ± 10 %
Frequency 50/60 Hz
Power consumption max. 2200 W
Power input 10 A
Weight (net) (including digestion tubes) 35 kg
Installation category II
Degree of pollution 2
Environmental conditions
Temperature
Altitude
Humidity
for indoor use only
5 - 40 °C
up to 2000 m
maximum relative humidity 80% for temperatures up to
30°C
Temperature range 50 °C to 420 °C (450 °C)
Temperature drift ± 5 °C > 200 °C / ± 2 °C < 200 °C
Table 3-7: Technical data COD Accessory
COD Accessory
Thermal stability of heating block ± 2 °C at temperatures < 200 °C
Heating up period Up to around 150 °C within 10 minutes
3.3 Materials used
Table 3-8: Materials used for the K-437
Component Material designation Material code
Housing Sheet steel DC01 + EVZ DIN 17162
Coating Polyester/epoxy PEP 31
Heating block Aluminium AlMgSi 1 DIN 3.2315
Insulation Thermal Ceramics 800 X-607
Rack Sheet steel, stainless 1.4301
Glass components Borosilicate 3.3 DIN/ISO 3585
Hose Ethylene/propylene terpolymer rubber EPDM
Table 3-9: Materials used for the COD Accessory
Component Material designation Material code
Rack COD Steel, stainless 1.4301
Digestion tube holder COD Steel, stainless 1.4301
Preparation block COD Aluminium AlMg4.5Mn H111 En-5083
Rack condenser COD PMMA
Stand for condenser COD PP gray
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4 Description of function
14 K-437 Operation Manual, Version A
4 Description of function
This chapter explains the basic principle of the instrument, shows how it is structured and gives a
functional description of the assemblies.
4.1 Functional principle of the Digest System
The Digest System K-437 is suitable for
digestion processes with concentrated boiling
sulphuric acid. The digestion parameters are
listed in the BUCHI application notes.
Fig. 4.1: Overview over the Digest System
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4 Description of function
15 K-437 Operation Manual, Version A
4.2 Functional principle of the COD Accessory
The COD Accessory is suitable for the digestion
of samples for a following COD determination. The digestion is followed by colorimetric
determination or photometric determination.
Application parameters are listed in official
methods or in the BUCHI Application Note
“COD determination”.
Fig. 4.2: Overview of the COD Accessory
4.3 Controls of the Digest System
2
4
3
1
6
5
a Indicator light for heating
b Start/Stop button
c Temp/Time button
d Arrow buttons
e Enter button
f Main switch
Fig. 4.3: Controls of the Digest System
4.4 Rear connections of the Digest System
1
2
a Mains supply with fuse
b Mains socket for Scrubber
Fig. 4.4: Rear connections of the Digest System
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5 Putting into operation
16 K-437 Operation Manual, Version A
5 Putting into operation
This chapter describes how the instrument is installed and gives instructions on initial startup.
NOTE
Inspect the instrument for damages during unpacking. If necessary, prepare a status report immediately to inform the postal company, railway company or transportation company.
Remove the transportation lock at the bottom of the instrument.
Keep the original packaging for future transportation.
5.1 Installation site
Install the instrument on a clean, flat and stable base.
NOTE
We recommend to operate the instrument under a ventilation hood.
ATTENTION
To ensure the instrument safety do not place any object on top of it.
ATTENTION
For safety reasons, make sure that the distance between the instrument and another object or the
instrument and a wall is at least 5 cm.
ATTENTION
If your are working with a Scrubber, place it on the left side of the K-437. The Scrubber ventilation is
located on the left side. In case the Digest System is placed on the left side, cool air will hit the digestion sample and cool it down, so that no digestion can take place.
5.2 Electrical connections
ATTENTION
Make sure that the voltage on the socket corresponds to the voltage given on the type plate of the
instrument (Digest System K-437 and Scrubber).
Always connect the instrument to an earthed socket. External connections and extension cables
must be provided with an earthed conductor lead (3-pole couplings, cable or plug equipment) as the
mains lead has a molded plug, thus avoiding risks due to inadvertent defective wiring.
Make sure that no electric sparks form in the instrument or its surroundings as they might damage
the instrument.
Connect the Digest System K-437 to the mains with the power cord contained in the scope of
delivery. To start the Scrubber automatically at the same time the digestion process starts, connect it
to the Digest System K-437 with the optional connection cable.
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5 Putting into operation
17 K-437 Operation Manual, Version A
5.3 Hose connections
Fit the EPDM hose to the Scrubber or the water jet pump to exhaust the digestion gases.
NOTE
Make sure that the hose connections are as short as possible.
WARNING
Danger of toxication. When working with a water jet pump, poisonous and caustic gases can escape
into the environment.
Make sure that the suction output is sufficient.•
ATTENTION
If the Scrubber is used without condensation step, the condensation that accrues must be caught by
means of a Woulff bottle between the Digest System and the Scrubber.
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6 Operation
18 K-437 Operation Manual, Version A
6 Operation
This chapter gives examples of typical instrument applications and instructions on how to operate the
instrument properly and safely.
WARNING
Risk of injury.
Never operate the instrument when glassware is damaged.•
ATTENTION
Switch on the K-437 before a connected instrument produces gases.
6.1 General information
The condensation zone of the sulphuric acid must not rise too high in the digestion tube (maximum of
5 cm below the rim of the tube).
Normally 18 - 20 ml of H2SO4 is used for a weighed portion of approx. 1 g of organic material. For
weighed portions over and above this, approx. 3 - 5 ml of H2SO4 (5 - 10 ml for greases and mineral
oils) must be used additionally for each additional gram of organic material.
WARNING
A rack filled with sample tubes and samples is heavy. Please consider the weight before transport.
ATTENTION
Hot, caustic sulfuric acid is used for the operation of the instrument. For this reason, personal protective equipment must be worn at all times when using this instrument or working in its immediate
proximity.
Close unused connections with glass caps.
It is absolutely essential that the seals on the suction pipes be properly installed and fit the glass
evenly.
To vaporize larger amounts of water (> 10 ml), it is advisable to use digestion rods as this will prevent
boiling delays. If the distillation temperature is too high, it is likely to cause substantial boiling delays.
The starting temperature should not be higher than 250 °C.
The digestion time depends on the substance to be digested. Information on this can be found in the
BUCHI application notes. If no BUCHI application is available, the digestion time must be ascertained
by means of experiments. (Once the solution has become clear, continue to boil the solution for about
30 minutes.) Once the samples have cooled off, the digestion tube can be connected directly to a
BUCHI distillation unit for distillation.
Due to different contact surfaces between the digestion tubes and the heating block, not all 20
samples boil simultaneously. However, as long as it is ensured that the digestion time and digestion
temperatures are sufficient, the different boiling times have no influence on the results.
If the digested samples are allowed to cool off for a long period of time, the samples might solidify
occasionally.
In this case, the sample must be liquefied again before it can be distilled:
by carefully adding a small quantity of distilled water, or•
by slightly warming it up in the Digest System.•
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6 Operation
19 K-437 Operation Manual, Version A
6.2 Kjeldahl digestion process
ATTENTION
Do not use cold water to cool down hot digestion tubes after digestion. The resulting temperature •
shock might lead to tensions in the glass.
Make sure that the 20 place rack containing the digestion tubes is placed in and removed from •
the digestion block with reasonable care.
Do not use glass beads. If the sample tends to boiling delays, use digestion rods, which are •
gentler for the glass tubes.
To carry out a Kjeldahl digestion, proceed as follows:
Switch the instrument on and preheat it to the required temperature.•
Place the digestion tubes into the rack.•
Pour the samples and reagents into the digestion tubes.•
Fit sealing covers over any vacant rack positions.•
Fit the sample rack into the fixture provided.•
Mount the suction unit, with the seals fitted, onto the digestion tubes.•
When the digestion temperature is reached (READY appears on the display) fit the sample rack, •
with the suction unit fitted, into the heating block and press the START button. (The connected
Scrubber will start automatically.)
Start up the Scrubber or water jet pump before gases can develop.•
After the digestion process is finished, put the sample rack into the cooling position, with the •
suction unit fitted, so that it can cool down.
When the cooling procedure is finished, press the STOP button to end the digestion process. The •
connected Scrubber will switch off.
The blinking LED “HEATING” indicates that the instrument is still hot and is being cooled by the •
ventilator. After the digestion is finished the instrument should remain connected to power for an
additional 30 minutes. Thus it is cooled and the service life of the built-in display is extended.
Repeat the procedure for additional digestion processes.•
6.3 Operating the K-437
Switching on the K-437
420 120
Press the main switch. The switch lights up
green.
The temperature and digestion time last
selected are displayed.
Editing parameters
The inputs can be changed by pressing the TEMP or TIME buttons. Enter the required temperature or
time by pressing the arrow buttons and confirm by pressing ENTER. If “0” is entered for the time, the
timer will be switched off and the operator must observe the digestion time.
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6 Operation
20 K-437 Operation Manual, Version A
Starting digestion
420 120
READY 422
Press the START button to start the heating
interval. The “READY” indicator on the display
shows that the set digestion temperature has
been reached. The samples with the suction module fitted can now be placed into the
digestion block.
The timer is started by pressing the START button again and the remaining digestion time is
indicated in the form of a countdown of figures
on the display. If the Scrubber is connected to
the K-437, it is started as soon as the START
button is pressed. If this is not the case, the
water jet pump must be started manually.
Editing the digestion parameters during the digestion process
420 120
READY 422 115
The inputs can be changed by pressing the
TEMP or TIME buttons. Press ENTER to confirm the changes. 420 120
RUN 422 86
End of digestion
420 120
FINISH 422 0
The heating is switched off at the end of the set
digestion time and a beep sound is audible to
inform the operator that the digestion process
is finished. The Scrubber continues to operate until the cooling time has ended or until the
STOP button is pressed. If “0” is entered for the
digestion time, no beep sound is audible and
the heating will not be switched off. The operator must observe the digestion time and, when
the procedure is finished, switch off the heating
by pressing the STOP button. The Scrubber
will continue to operate until the STOP button is
pressed a second time.
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6 Operation
21 K-437 Operation Manual, Version A
Interrupting the digestion
420 120
ABORT 422 53
The digestion process can be interrupted at
any time by pressing the STOP button. In this
case, the heating is switched off. The Scrubber
will continue to operate until the STOP button is
pressed for a second time.
Cooling the digested samples
Both the sample rack and the fitted suction module are moved into the cooling position. The Scrubber
or the water jet pump will continue to operate. After the cooling procedure is finished the Scrubber
can be switched off by pressing the STOP button.
Removing the sample rack
Swivel back the suction module and remove the sample rack with the cooled samples.
After the digestion is finished the instrument should remain connected to the power for another 30
minutes. Thus the instrument is cooled by a built-in ventilator and the service life of the built-in display
is extended.
Power failure
ERR1 420 20
POWER 401 12
The digestion process is interrupted if a power
failure occurs. The heating is switched off automatically.
Switching off the K-437
Press the main switch. The light in the switch will go off.
Page 22
6 Operation
22 K-437 Operation Manual, Version A
6.4 Service menu
Accessing the service menu
K-437
SERVICE
Press the STOP button for approx. 3 seconds.
The service menu will appear. Use the STOP
button to move to the next submenu.
Contrast
The contrast is corrected by pressing the arrow buttons.
Maximum temperature
MAX 440
TEMP
For safety reasons, the maximum temperature ex works is limited to 420 °C. If a lower or
higher digestion temperature is required, it can
be changed here within a range of between
100 °C minimum and 450 °C maximum.
ATTENTION
Digestion temperatures of over 420 °C may result in a loss of nitrogen. If digestion times exceed 180
minutes, the rise in the temperature at the rack may result in the seals being damaged.
Temperature calibration
OFFSET 420 20
ACTUAL 418 21
If the actual temperature measured is different
from the specified temperature, use the arrow
buttons to correct it.
Page 23
7 Maintenance and repairs
23
K-437 Operation Manual, Version A
7 Maintenance
This chapter gives instructions on all maintenance work to be performed in order to keep the instrument in good working condition.
WARNING
All maintenance and repair work requiring the opening or removal of instrument covers may only be
carried out by trained personnel and with the tools provided for this purpose.
WARNING
Electrical hazard:
Prior to all maintenance work on the instrument switch off the power supply and remove all •
sources of flammable vapor.
ATTENTION
Always wear personal protective equipment such as protective eye goggles, protective clothing and
gloves when maintaining the instrument.
Check the instrument for proper operation after any repair work.
7.1 Housing
Check the housing for defects (switches, plugs) and clean it regularly with a damp cloth.
ATTENTION
Never use solvents as cleaning agents as these might damage the instrument.
As the housing is made of metal and covered with an acid-resistant coating, any acid drops must •
be wiped away immediately with a damp cloth.
7.2 Glass parts
The glass parts can be taken out and cleaned with commercially available cleaning agents or in an
ultrasonic bath. After the glass parts have been cleaned and fully dried, check each part visually for
cracks, scratches and for any parts or sections that might have splintered off. Take out and replace
any damaged glass parts.
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7 Maintenance and repairs
24 K-437 Operation Manual, Version A
7.3 Digestion tubes
ATTENTION
Do not use cold water to cool down hot digestion tubes after digestion. The resulting temperature
shock might lead to tensions in the glass.
incorrect correct
Use the optional retaining plate to wash the digestion tubes
together with the sample rack in the laboratory washing instrument. Thus the tubes will not be damaged during washing.
To clean the tubes, proceed as follows:
Mount the retaining plate onto the rack at the points provided.•
Put the retaining plate with the rack into the laboratory washing •
instrument with the tube openings pointing downwards.
Remove the retaining plate after washing. The digestion tubes •
are now clean and ready for the next analysis.
7.4 Sealing system
ATTENTION
When removing and reinstalling the seals and gaskets, make sure not to damage them. Always move
them perpendicularly to the axis of the glass parts and ensure no damage occurs to the sealing lip.
Never apply grease to the seals and never touch them with sharp objects, otherwise they will get
damaged.
7.4.1 Cleaning the seals
To prolong the lifetime of the seals, rinse them regularly with water, especially if working with crystalline
products. Afterwards, dry them with a soft cloth.
7.4.2 Replacing the seals
Seals are subject to wear and tear, thus you should check them regularly and replace them, if necessary.
7.5 Exhaust unit
The exhaust unit can be cleaned under running water or in the laboratory washing instrument.
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7 Maintenance and repairs
25
K-437 Operation Manual, Version A
7.6 Power supply fuse
To change the fuse, proceed as follows:
Pull out the power supply cable.•
Remove the fuse holder.•
Replace the fuse with a new fuse of the same type •
(230 V, T 10 A L 250 V).
Put the fuse holder back.•
7.7 Customer service
Only authorised service personnel are allowed to perform repair work on the instrument. These
persons have a comprehensive technical training and knowledge of possible dangers which might
arise from the instrument.
Addresses of official BUCHI customer service offices are given on the BUCHI website under:
www.buchi.com. If malfunctions occur on your instrument or you have technical questions or application problems, contact one of these offices.
The customer service offers the following:
Spare part delivery•
Repairs•
Technical advice•
Page 26
8 Troubleshooting
26 K-437 Operation Manual, Version A
8 Troubleshooting
This chapter helps to resume operation after a minor problem has occurred with the instrument. It lists
possible occurrences, their probable cause and suggests how to remedy the problem.
The troubleshooting table below lists possible malfunctions and errors of the instrument. The operator
is enabled to correct some of those problems or errors by him/herself. For this, appropriate corrective
measures are listed in the column “Corrective measure”.
The elimination of more complicated malfunctions or errors is usually performed by a BUCHI technical
engineer who has access to the official service manuals. In this case, please refer to your local BUCHI
customer service agent.
8.1 Malfunctions and their remedy
Table 8-1: General malfunctions and their remedy
Malfunction Possible cause Corrective measure
ERR 1 POWER The digestion process is interrupted
due to a power failure.
The heat is turned off automatically.
Remedy the power failure. Afterwards, delete the error message
from the display by pressing “STOP”.
ERR 2 TEMP The current heating block tempera-
ture exceeds the programmed
temperature by more than 10 °C.
The digestion is automatically
stopped and the heat is switched off.
ERR 3 SHUT OFF MAINS Due to a blocked or defective venti-
lator the internal temperature of the
instrument exceeds 60 °C.
Switch off the instrument immediately and contact the BUCHI
customer service.
Page 27
9 Shutdown, storage, transport and disposal
27 K-437 Operation Manual, Version A
9 Shutdown, storage, transport and disposal
This chapter instructs how to shut down the instrument, how to pack it for storage or transport, and
specifies the storage and shipping conditions.
9.1 Storage and transport
WARNING
Biohazard:
Remove all dangerous substances from the instrument and clean it thoroughly.•
Store and transport the instrument in its original packaging.
WARNING
The K-437 weighs 35 kg. For this reason, manual handling of the instrument should always be done
by at least two people.
9.2 Disposal
To dispose of the instrument in an environmentally friendly manner, a list of materials is given in
chapter 3. This helps to ensure that the components are separated and recycled correctly.
Please follow valid regional and local laws concerning disposal.
Page 28
10 Spare parts
28 K-437 Operation Manual, Version A
10 Spare parts
This chapter lists spare parts, accessories, and options including their ordering information.
Order the spare parts from BUCHI. Always state the product designation and the part number when
ordering spare parts.
Use only genuine BUCHI consumables and genuine spare parts for maintenance and repair to assure
good system performance and reliability. Any modifications to the spare parts used are only allowed
with the prior written permission of the manufacturer.
1
5
3
4
2
6
7
Fig. 10.1: Spare parts K-437
Table 10-1: Spare parts K-437 and general
Position Product Order number
a
Rack, 20 spaces, complete 38621
b
Sample tube, 300 ml 37377
c
Vapor collection tube 38530
d
Suction tube standard 38527
Suction tube with condensate trap 38640
Suction module standard, complete 38561
e
EPDM hose, 1.5 m, 8 mm 11056005
f
Glass caps (4 pieces) 40049
g
Set of sealing rings PTFE, 20 pieces 38623
Fuse, set of 10 fuses 16952
Fixation pins for additional block (10 pieces) 11055194
Metal frame for suction module 11056101
Digestion rods 43087
Kjeldahl tablets
Titanium 11057980
Titanium Micro 11057981
Missouri 11057982
Page 29
10 Spare parts
29 K-437 Operation Manual, Version A
Table 10-1: Spare parts K-437 and general (cont.)
Position Product Order number
ECO 11057983
Antifoam 11057984
Copper Micro 11057985
Page 30
11 Declarations and requirements
30 K-437 Operation Manual, Version A
11 Declarations and requirements
11.1 FCC requirements (for USA and Canada)
English:
This equipment has been tested and found to comply with the limits for a Class A digital device,
pursuant to both Part 15 of the FCC Rules and the radio interference regulations of the Canadian
Department of Communications. These limits are designed to provide reasonable protection against
harmful interference when the equipment is operated in a commercial environment.
This equipment generates, uses and can radiate radio frequency energy and, if not installed and used
in accordance with the instruction manual, may cause harmful interference to radio communications.
Operation of this equipment in a residential area is likely to cause harmful interference in which case
the user will be required to correct the interference at his own expense.
Français:
Cet appareil a été testé et s'est avéré conforme aux limites prévues pour les appareils numériques
de classe A et à la partie 15 des réglementations FCC ainsi qu’à la réglementation des interférences
radio du Canadian Department of Communications. Ces limites sont destinées à fournir une protection adéquate contre les interférences néfastes lorsque l’appareil est utilisé dans un environnement
commercial.
Cet appareil génère, utilise et peut irradier une énergie à fréquence radioélectrique, il est en outre
susceptible d’engendrer des interférences avec les communications radio, s’il n’est pas installé et
utilisé conformément aux instructions du mode d’emploi. L’utilisation de cet appareil dans les zones
résidentielles peut causer des interférences néfastes, auquel cas l’exploitant sera amené à prendre les
dispositions utiles pour palier aux interférences à ses propres frais.
Page 31
11 Declarations and requirements
31 K-437 Operation Manual, Version A
11.2 Declaration of conformity
Page 32
Page 33
Page 34
BÜCHI Labortechnik AG
CH-9230
Flawil 1 / Switzerland
T +41 71 394 63 63
F +41 71 394 65 65
www.buchi.com Quality in your hands
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