Buchi K-435 User manual

1
Digestion Unit K-435 Table of Contents
Table of Contents
Please read these operating instructions carefully before using
the Digestion Unit K-435. Keep these instructions in the
proximity of the apparatus so that you can consult them
immediately whenever necessary.
The apparatus should not be connected to the power supply
and turned on until all of the necessary preparations have
been completed. Chapter 2 contains important safety
instructions. Read them carefully; they are essential for the
safe operation of the apparatus.
Technical changes may be made without prior notice. The
reprinting of these operating instructions or excerpts thereof
is expressly forbidden. They may not, either wholly or in part,
be reproduced or rewritten, copied, or distributed by the use
of electronic or optical systems without the express written
permission of the firm BÜCHI Labortechnik AG. All rights
reserved. Copyright © BÜCHI Labortechnik AG 2008
en, Version E Order code
K-435 Operating Instructions 96721
1Supplied Materials 2
2Safety 3
2.1 Symbols 3
2.2 Requirements for the User 3
2.3 Proper Use 3
2.4 Improper Use 4
2.5 General Risks 4
2.6 Safety Measures 4
3Function 6
3.1 Functional Principle 6
4Installation 7
4.1 Placement 7
4.2. Unpacking 7
4.3 Connections to Power Supply 7
4.4 Hose Connections 8
5Operation 9
5.1 Operational Features 9
5.2 Operational Features and their Function 9
5.3 General 9
5.4 Conducting Kjeldahl Digestion 11
5.5 Conducting Kjeldahl Digestion in
Remote Control Operation 11
5.6 Malfunctions 12
6Maintenance 13
6.1 General 13
6.2 Upkeep 13
6.3 Seals 13
6.4 Changing Insulation 13
6.5 Changing O-rings 14
6.6 Power Supply Fuses 14
6.7 Customer Service 14
7Taking out of operation 15
7.1 Storage/Transport 15
7.2 Disposal 15
8Replacement parts 16
9Appendix 17
9.1 Technical Data 17
9.2 Materials Used 17
9.3 FCC requirements 18
9.4 Declaration of confirmity 19

2
Digestion Unit K-435
1 Scope of delivery
Figure 1: K-435
1Scope of delivery
Description Order code
Version:
K-435 standard 230 V 50/60 Hz 38130
Table1: Apparatus models
Enclosed parts:
4Digestion tubes 37377
2Racks 26730
2Upper insulation plate 26736
2Suction module, complete 26842
2Connections to suction module 26875
2Digestion glass holders, complete 38080
1Contact guard, pre-mounted 26878
1Power cable of the following types:
Type CH 10021
Type Schuko 10029
Type GB 17833
Type AUS 17834
Type USA 33756
1Set of operating instructions in one of
the following languages:
German 96720
English 96721
French 96722
Italian 96723
Spanish 96724
1Packaging 34447
Table 2: Enclosed parts
Optional Accessories:
Water jet pump made of plastic 02913
Cover 17396
Seal PTFE to suction pipe 22442
Collection basin for suction pipe 27737
Condensate flask, complete 25100
Suction module for H2O2digestion 37399
Suction pipe with condensate control 26880
Connecting cable to Scrubber B-414 14738
Control cable to B-436 26849
Büchi Scrubber B-414 37876
Non Kjeldahl digestion set 43677
Suction pipe with ball joint 40158
Table 3: Optional accessories

3
Digestion Unit K-435 2 Safety
2Safety
The apparatus is manufactured according to state-of-the-art
technology and recognized safety regulations.
Nevertheless, using this apparatus can lead to certain risks
and dangers:
•If the apparatus is used by inadequately trained personnel.
•If the apparatus is not used according to these instructions.
2.1 Symbols
Stop
Information about risks which can lead to extensive property
damage or to serious or life-threatening personal injury.
Warning
Information about risks which can lead to personal injury or to
property damage.
Reference
Information which refers to technical requirements. Failure to
heed these requirements can lead to malfunctions, inefficiency,
and production losses.
2.2 Requirements for the User
The apparatus may be used only by laboratory personnel or
other persons who due to their training or professional
experience are capable of recognizing possible dangers which
might arise from the use of the apparatus.
2.3 Proper Use
The apparatus was designed and built for laboratory use. Its
proper use is the heating of concentrated sulfuric acid for
oxidation of organic sample components.

4
Digestion Unit K-4352 Safety
2.4 Improper Use
Any use of the apparatus other than that given above or any
use of the apparatus which is not in accordance with the
technical data shall be regarded as a misuse. The operator
bears the sole responsibility for any and all damage which
may result from such misuse.
In particular, the following uses of the apparatus are prohibited:
•Use of the apparatus in rooms which require ex-protected
apparatus.
•Preparing samples which can explode or ignite due to a
blow, friction, heat, or sparks.
2.5 General Risks
In general, risks can arise from
•Hot sulfuric acid
•Flammable gases or solvent vapors in the immediate vicinity
of the apparatus
•Damaged glass equipment
•Placing the apparatus too close to the wall
(see Chapter 4.1, Placement)
•Burns caused by touching hot glass parts.
The removal of covers using standard tools is prohibited except
for authorized maintenance personnel. The apparatus must
not be started up glass equipment is damaged.
Touching any parts of the apparatus carrying electrical current
can result in fatal injury!
2.6 Safety Measures
It is recommended that the apparatus be operated only under
a ventilation hood.
Protective clothing such as goggles, gloves, and labo-
ratory coats must be worn during operation of the apparatus.
These operating instructions must be regarded as an integral
part of the Digestion Unit K-435 and be available at all times
to operating personnel at the place of operation of the
apparatus. This also applies to instructions in other languages,
which may be ordered separately.

5
Digestion Unit K-435 2 Safety
Modifications
Modifications of the apparatus or of spare parts or accessories
as well as the use of spare parts or accessories other than
those mentioned in these operating instructions is allowed only
with the prior written permission of BÜCHI Labortechnik AG.
Responsibility of the Operator
The operator is responsible for the instruction of his personnel.
Copies of these operating instructions in various languages
can be ordered for this purpose.
The operator shall inform the manufacturer without delay of
any safety-related events which might occur during operation
of the apparatus.
If safe operation of the apparatus no longer appears possible,
the apparatus must be shut down and secured against
unintentional operation.
It must be assumed that safe operation is no longer possible
•if there is visible damage to the apparatus;
•if the apparatus is no longer functioning;
•following a long period of storage under unfavorable
conditions;
•following transport under difficult conditions.
The apparatus must not be operated with flammable
substances.
If it becomes necessary to involve Büchi Service, safety and
environmental protection considerations require that
dangerous substances (e.g., according to EU Regulations L
360, 1976/79, or VBG 16) on or in the apparatus must be
indicated and declared.

6
Digestion Unit K-4353 Function
3Function
Figure 2: Functional Principle of the K-435
The Digestion Unit K-435 is suitable for digestions using boiling
concentrated sulfuric acid within a temperature range of up
to approximately 370° C.
3.1 Functional Principle
aDigestion glasses
bHeating
cSuction module
dHose for water jet pump or to Scrubber B-414
b
a
c
d

7
Digestion Unit K-435 4 Installation
4Installation
4.1 Placement
The apparatus must be set up on a stable, clean, and level
surface.
The apparatus must be placed with its back at a minimum of
30 cm from walls and other objects in order to prevent
damage. Containers, chemicals, or other apparatus may not
be placed behind the unit.
4.2 Unpacking
Keep the original packaging for the event of a later transport.
If the packaging has been damaged, check the apparatus
carefully for glass breakage or damage to the casing.
Ensure that the voltage of the power outlet corresponds to
the voltage given on the apparatus plate. Always connect the
apparatus to a grounded outlet. This will avoid risks due to
internal defects.
4.3 Connection to Power Supply
Before the K-435 is turned on for the first time, ensure that
the power supply voltage corresponds to the voltage given on
the apparatus plate.
Then connect the apparatus to the power supply with the
apparatus cable.

8
Digestion Unit K-435
u
4 Installation
4.4 Hose Connections
Place the contact guard (A) with the pre-mounted hoses on
the apparatus as shown in the photo.
Assemble the connection to the suction module (B) and mount
it on the hose (C) and on the suction module (D).
To exhaust the digestion gases, connect the EPDM hose (E)
to the Scrubber B-414 or a water jet pump (e.g., one made
of plastic, Article No. 02913). Please note that the shortest
possible hose connections should be used.
When a water jet pump is used, unpleasant odors can escape
into the immediate surroundings if the suction is inadequate.
If only a suction module (D) is used, the unused hose (C) must
be closed with a rubber stopper.
The Scrubber B-414 220 V, 240 V can be connected directly
to the K-435 with a connecting cable (Art. No. 14738).
However, care must be taken that the voltage of the scrubber
corresponds to the voltage of the K-435.
If the apparatus is operated without remote control, the control
of the scrubber B-414 is regulated by the main switch on the
Digestive Unit, or in other cases with the Control Unit B-436.
026757 002073
026240 003577
Figure 3: Hose connections, enlarged view
Figure 4: Connection to suction pipe.
uu
u
u
u
u
u
A
E
C
BDDB
C
uD

9
Digestion Unit K-435 5 Operation
5Operation
Figure 6: Placement of the controls and operational elements on the back
d
b
c
Figure 5: Placement of controls and operational elements on the front
Figure 7: Condensation zone for sulfuric acid
5.1 Operational features
aMain switch
bHeat regulator
cWarning light for heating
dPower supply connection with fuse
ePower socket for Scrubber B-414
fConnection for B-436
5.2 Operational features and their function
Main switch a
Turns the apparatus on and off.
Heat regulator b
Regulates the heat in stages from 1-10.
5.3 General
The heating process causes the digestion glasses to be heated
evenly from all sides, ensuring good distillation characteristics
(no retardation of ebullition). Ebullition beads are needed only
for the evaporation of quantities of water greater than 10 ml
(do not use glass beads).
It is important that the condensation zone of the sulfuric acid
in the digestion glass not rise too high (maximum of 5 cm
under the edge of the glass).
As a rule, 18-20 ml H2SO4 will be used for a sample weight of
approximately 1 g of organic material.
If the sample weight is higher, approximately 3-5 ml H2SO4
(for fats and mineral oils, 5-10 ml) must be used for every
additional gram of organic material.
abc
ef

10
Digestion Unit K-4355 Operation
Hot, caustic sulfuric acid is used for the operation of this
apparatus. For this reason, protective goggles must be worn
at all times when using this apparatus or working in its
immediate proximity. Close unused connections with plug caps
(Art. No. 17396).
It is absolutely essential that the seals on the suction pipes be
properly installed and fit the glass evenly!
The proper heat setting is dependent on various factors such
as the digestion quantity, the type of reagents, etc.
Normally digestion of the samples will be conducted at the full
setting in order to minimize the amount of time needed for the
procedure.
The digestion time depends on the material being digested
and must be determined by actual practice (continue boiling
the solution for approximately 15 minutes after it has become
clear). After the sample has cooled, the digestion glass can
be connected directly to a Büchi Distillation Unit for distilling.
If the digested samples are allowed to cool for a long period of
time, the sample will occasionally solidify.
Before it can be distilled, the sample must be liquefied again:
•by carefully adding a small quantity of distilled water, or
•by slightly warming it in the Digestion Unit.
Figure 8: Seals
Figure 9: K-435

11
Digestion Unit K-435 5 Operation
5.4 Conducting Kjeldahl Digestion
•Turn on the apparatus aand preheat it at Setting 10 for
approx. 5 minutes.
•Wear protective goggles!
•Place the digestion glasses in the digestion glass holder b
on the rack c.
•Add the sample and the reagents to the digestion glasses
d.
•Close the unused connecting pieces with plug caps
(Art. No. 17396).
Never operate the apparatus with
empty digestion glasses!
•Place the suction module ewith the mounted seals over
the digestion glass holder..
•Turn on scrubber or water jet pump before any gases form.
5.5 Conducting Kjeldahl Digestion in
Remote Control Operation
•Connect the Büchi Control Unit B-436 to the Digestion
Unit and turn on the apparatus.
•Enter the parameters on the B-436.
•Set the regulator on the Digestion Unit at Setting 0.
•Place the digestion glasses in the digestion glass holder
on the rack.
•Add the samples and the reagents to the digestion glasses.
•Close the unused connecting pieces with plug caps
(Art. No. 17396).
Never operate the apparatus with
empty digestion glasses!
•Place the suction module ewith the mounted seals over
the digestion glass holder.
•Begin digestion by pressing the START button on the
Control Unit B-436 (Scrubber B-414 starts automatically;
manually start the water jet pump before any gases form).
b
c
d
a
Figure 10: Operation of K-435
e

12
Digestion Unit K-4355 Operation
5.6 Malfunctions
Malfunction Possible Cause Correction
Heating elements 1. Apparatus is not connected to -Connect the apparatus to the power supply
do not heat power supply
2. Apparatus is turned off -Turn off apparatus
3. Heat regulator is at setting „0“ -Set to setting "10"
4. Heat regulator is defective -Replace regulator
5. Heating elements are defective -Replace heating elements
Light does not Light is defective Replace light
come on (H 1)
Table 4: Malfunctions

13
Digestion Unit K-435 6 Maintenance
6Maintenance
6.1 General
The casing of the Digestion Unit K-435 is made of metal and
covered with an acid-resistant coating.
To avoid damage to this synthetic coating, any acid drops
should be wiped away with a damp cloth.
Avoid any scratching of the coating whatsoever!
6.2 Upkeep
Daily care:
•Check glass parts for damage.
•Clean synthetic parts with a damp cloth.
The glass parts are cleaned.
6.3 Seals
The seals are expendable material and must be replaced if
they are damaged or no longer seal properly.
Inspection and Maintenance Requirements
Observe all guidelines which aim at maintaining the apparatus
in operable condition. This includes regular cleaning and
inspection for possible damage.
The operator shall carefully check the apparatus for proper
operation following every repair.
6.4 Replacing Insulation
Before changing any components of the apparatus, disconnect
the apparatus from all power sources in order to prevent
possible electric shocks.
Electric and electronic components must be replaced by
authorized personnel only.
Do not attempt to replace any components when the appara-
tus is still hot or warm. Allow it to cool first!
Upper Insulation Plate
This insulation can easily be reached and can be replaced
without using any tools.

14
Digestion Unit K-4356 Maintenance
➬
1
2
ç
Figure 11: Changing O-Rings
6.5 Changing O-Rings
•Cut through the damaged washer with a knife of scalpel
•Remove the glass holder
•Draw the new washer over the suction module (cf. photo)
•Replace glass holder and secure with washer
6.6 Power Supply Fuses
The power supply fuses can be changed by following these
steps:
•Pull out the power supply cable
•Remove the fuse holder a
•Replace the fuse b with a new fuse of the same values:
- 230V:T 10A L 250V
•Replace the fuse holder
6.7 Customer Service
Work on or in the apparatus may be carried out only by
authorized service personnel. These are people with sound
technical vocational training and knowledge of the risks which
result when safety measures are disregarded. BÜCHI customer
service offices have service manuals specific to the various
apparatus; these manuals can be obtained only by authorized
personnel.
The addresses of the official BÜCHI customer service offices
are listed on the last cover page of these operating instructions.
If malfunctions arise or if you have technical questions or
problems in operating the apparatus, please consult these
offices.
BÜCHI’s customer service provides the following services:
•Spare parts service
•Repair service
•Maintenance service
•Technical consulting
Figure 12: Apparatus plug, built-in
a
b

15
Digestion Unit K-435 7 Taking out of operation
7Taking out of operation
Any dangerous substances must be removed and the
apparatus must be cleaned thoroughly. This avoids any risk
that persons could be injured by contact with dangerous
substances.
7.1 Storage/Transport
After it has been cleaned, return the apparatus to the original
packaging for storage and transport.
7.2 Disposal
Chapter 9, Appendix, Table 7 contains a list of the materials
used in the manufacture of the most important parts of the
apparatus so that it can be disposed of in accordance with
environmental regulations. This ensures that the various parts
can be separated and recycled properly. Dispose of electronic
components in accordance with the applicable regulations.
Please observe the valid regional and local statutes in disposing
of the apparatus.

16
Digestion Unit K-435
8 Replacement parts
8Replacement parts
Only original accessories and spare parts from BÜCHI
guarantee that the apparatus will function properly and safely.
Spare parts and accessories from other manufacturers may
be used only with the express permission of the manufacturer.
The above-mentioned spare parts may be used in assembling
or dismantling the apparatus only as described in Chapter 6
of these operating instructions. It is forbidden to allow third
parties to view or possess this manual; production of the
apparatus based on this manual is forbidden.
8.1 Replacement parts
l
j
f
k
c
d
e
g
b
a
i
h
m
e
No.Description Order code
aConnection to suction pipe, complete 26875
bSeals Viton Standard (6 seals) 38122
Seal PTFE (1 seal) 22442
cO-Ring 26785
dSuction pipe 26755
eGlass holder set for suction pipe, 26877
including 2 O-rings (26785)
fUpper insulation plate 26736
gContact guard 26797
hDigestion glass holder, complete 38080
iCap for digestion glass holder 26791
jFlat spring (12 springs) 38123
kPlug cap 17396
lDigestion glasses (4 glasses) 37377
mRack 26730
EPDM hose 8 mm 26275
T-piece Ø 10 mm 26835
Fuses T10A L250V (10 pcs) 16952
Suction pipe with ball joint 40158
Suction module for H2O2 digestion 37399
Rubber gukos for H2O2 suction module 44495
Funnel with frit for H2O2 suction module 44494
Table 5: Replacement parts

17
Digestion Unit K-435 9 Appendix
9Appendix
9.1 Technical Data
Measurements (width x height c depth) 275 x 600 x 570 mm
Voltage 230 V ± 10%, 50/60 Hz
Connected value 2200 Watt
Power input 10 Ampère
Weight (net) approx.. 20,9 kg
Overvoltage category II
Pollution degree 2
Ambient conditions for indoor use only, below 2000 m.s.l.
maximum relativ humidity 80% for temperatures up to 30°C,
temperature 10 - 40°
Table 6: Technical data
9.2 Materials used
Description Materials Material code
Housing Front- and rearside Polyurethane PUR
Side panels Stainless steel / Perfluoralkoxy 1.4435 / PFA
Glass parts Borosilikat-Glas 3.3 DIN/ISO 3585
Contact guard Polyphenylensulfrol PPS
Insulation Saprolan 85K / Porextherm WDS Ultra
Metals Stainless steel
Hoses Ethylene propylene diene monomer EPDM
rubber
Table 7: Materials used

18
Digestion Unit K-435
9 Appendix
9.3 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, pusuant 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 like 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 règlementation FCC à la règlementation des radio-interférences du Canadian Department of
communications. Ces limites sont destinées à fournir une protection odéquate contre les interférences nétastes
lorsque l'appareil est utilisé dans un environnement commercial.
Cet appareil génère, utilise et peut radier une énergie à fréquence radioélectrique, il est en outre susceprible d'engendrer
des interferences 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 nèfastes,
auquel cas l'exploitant sera amené à prendre les dispositions utiles pour polier aux interférences à ses propres frais.