Buchi SpeedDigester K-425 User manual

K-425 / K-436 SpeedDigester
Operation Manual
11593346B en

Imprint
Product Identification:
Operation Manual (Original), SpeedDigester K-425 / K-436
11593346B en
Publication date: 04.2016
BÜCHI Labortechnik AG
Meierseggstrasse 40
Postfach
CH-9230 Flawil 1
E-Mail: [e-mail]
BUCHI reserves the right to make changes to the manual as deemed necessary in the light of experience; espe-
cially in respect to structure, illustrations and technical detail.
This manual is copyright. Information from it may not be reproduced, distributed, or used for competitive purpos-
es, nor made available to third parties. The manufacture of any component with the aid of this manual without
prior written agreement is also prohibited.

Table of contents
3K-425 / K-436 Operation Manual, Version B
Table of contents
1 About this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2 Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.1 User qualification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Proper use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Improper use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4 Safety warnings and safety signs used in this manual . . . . . . . . . . . . . . . . . . 7
2.5 Product safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
2.5.1 General hazards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
2.5.2 Warning labels on housing and assemblies . . . . . . . . . . . . . . . . . . . . . . 10
2.5.3 Personal protective equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.5.4 Built-in safety elements and measures . . . . . . . . . . . . . . . . . . . . . . . . 11
2.6 General safety rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Scope of application and delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.1 Available system configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.2 Accessories for 300 ml sample tubes (for standard applications) . . . . . . . . . . . 14
3.1.3 Accessories for 500 ml sample tubes (for large sample volumes / at low nitrogen level) 15
3.1.4 Accessories for 3rd party production, 250 ml sample tubes . . . . . . . . . . . . . . 15
3.2 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.2.1 SpeedDigester K-425 / 110 – 120 V version . . . . . . . . . . . . . . . . . . . . . . 16
3.2.2 SpeedDigester K-425 / 220 – 240 V version . . . . . . . . . . . . . . . . . . . . . . 17
3.2.3 SpeedDigester K-436 / 220 – 240 V version . . . . . . . . . . . . . . . . . . . . . . 18
3.3 Materials used. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4 Description of function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.1 Functional principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5 Putting into operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1 Installation site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2 System fixation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.3 Electrical connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.1 Operating controls and housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.1.1 SpeedDigester K-425 — front side . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.1.2 SpeedDigester K-425 — rear side. . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.1.3 SpeedDigester K-436 — front side . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.1.4 SpeedDigester K-436 — rear side. . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.2 Preparing of SpeedDigester, suction module(s) and sample tubes. . . . . . . . . . . 27
6.2.1 Kjeldahl digestion —preparing sample tubes. . . . . . . . . . . . . . . . . . . . . . 28
6.2.2 Peroxide digestion—preparing sample tubes . . . . . . . . . . . . . . . . . . . . . 29
6.2.3 Installing a suction module and sample tubes (300 ml). . . . . . . . . . . . . . . . . 29
6.2.4 Installing 500 ml sample tubes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.2.5 Starting up the SpeedDigester . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.3 Performing a Kjeldahl digestion process. . . . . . . . . . . . . . . . . . . . . . . . 34
6.3.1 Preparational steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Table of contents
4K-425 / K-436 Operation Manual, Version B
6.3.2 Starting a digestion process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.4 Performing a peroxide digestion process . . . . . . . . . . . . . . . . . . . . . . . 35
6.4.1 Preparational steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.4.2 Starting a digestion process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.5 Finishing a digestion process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
6.6 Optional 'Stand with drip tray' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
7 Maintenance and repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
7.1 Customer service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2 General condition and cleaning instructions . . . . . . . . . . . . . . . . . . . . . . 42
7.2.1 Breakage of glassware inside a housing chamber . . . . . . . . . . . . . . . . . . . 43
7.2.2 Liquid ingress into the instrument . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.3 Glass component conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.3.1 Sample tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.4 Sealing system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.5 Rack system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.5.1 300 ml sample tube support spring . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.5.2 500 ml sample tube support spring . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.6 Protection cover at the front . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
8 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.1 Malfunctions and their remedy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.2 Device fuses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
9 Shutdown, storage, transport and disposal . . . . . . . . . . . . . . . . . . . . . . . . 49
9.1 Storage and transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
9.2 Disposal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
9.2.1 Thermostat(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
10 Spare parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
10.1 Spare parts, optional accessories and consumables . . . . . . . . . . . . . . . . . 52
11 Declarations and requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
11.1 FCC requirements (for USA and Canada) . . . . . . . . . . . . . . . . . . . . . . . 55

1 About this manual
5K-425 / K-436 Operation Manual, Version B
1 About this manual
This manual describes the SpeedDigester K-425 / K-436 and provides all information required for its
safe operation and to maintain it in good working order.
It is addressed to laboratory personnel and operators in particular.
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. Technical data
are subject to change without notice.
Note
The symbols pertaining to safety (WARNINGS and ATTENTIONS) are explained in chapter 2.
This manual is copyright. Information from it may not be reproduced, distributed or used for competi-
tive 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.

2 Safety
6K-425 / K-436 Operation Manual, Version B
2 Safety
This chapter introduces the safety concept of the instrument and contains general rules of behavior
and warnings from direct and indirect hazards concerning the use of the product.
For the users safety, all safety instructions and safety messages in the individual chapters shall
be strictly observed and followed. Therefore, the manual must always be available to all persons
performing any tasks described herein.
2.1 User qualification
The instrument may only be used by laboratory personnel and other persons who on account of
training and professional experience know the potential dangers that can develop when operating the
instrument.
Untrained personnel, or persons who are currently being trained, require careful supervision by a
qualified person. This Operation Manual serves as a basis for training.
2.2 Proper use
The SpeedDigester K-425 / K-436 has been designed and built for laboratory use only. Its intended
use is to allow digestion of samples with concentrated acids or peroxides by heating up the probe.
A suction unit (e.g. Scrubber or water jet pump) has to be connected to the suction module to safely
withdraw fumes which will emerge during digestion. In any case, all exhausts and fumes leaving the
system or assemblies such as Scrubber or water jet pump have to be removed instantly inside a
fume hood. This is mandatory to remove all possibly hazardous substances (e.g. acid fumes) from the
working area. The ventilation system of the fume hood has to be equipped with safety measures such
as outlet filters to avoid contamination of the environment.
When the SpeedDigester K-425 / K-436 is used in combination with other instruments (e.g. Scrubber
and fume hood) all related manuals are to be fully observed.
2.3 Improper use
Applications not mentioned in section 2.2 are considered to be improper. Applications which do not
comply with the technical data (see section 3 of this manual) are also considered to be improper.
The operator bears the sole risk for any damages or hazards caused by improper use!
The following uses are expressly forbidden:
• Digestion operations outside an active fume hood.
• Digestion of samples (e.g. food and feed) in nitrosulfuric acids which can produce explosive nitro
compounds.
• Digestion of sample material of unknown composition in nitrosulfuric acids.
• Use of samples which can explode or ignite due to shocks, friction, heat or sparks.
• Installation or use of the instrument in rooms, which require ex-protected instruments.
• Use of glassware which is not specified in section 2.5.4.

2 Safety
7K-425 / K-436 Operation Manual, Version B
2.4 Safety warnings and safety signs used in this manual
DANGER, WARNING, CAUTION and NOTICE are standardized signal words for identifying levels of
hazard seriousness of risks related to personal injury and property damage. All signal words, which are
related to personal injury are accompanied by the general safety sign.
For your safety it is important to read and fully understand the table below with the different signal
words and their definitions!
Sign Signal word Definition Risk level
DANGER Indicates a hazardous situation which, if not avoided, will result in
death or serious injury. ★★★★
WARNING Indicates a hazardous situation which, if not avoided, could result
in death or serious injury. ★★★☆
CAUTION Indicates a hazardous situation which, if not avoided, may result
in minor or moderate injury. ★★☆☆
no NOTICE Indicates possible property damage, but no
practices related to personal injury.
★☆☆☆
(property damage only)
Supplementary safety information symbols may be placed in a rectangular panel on the left to the
signal word and the supplementary text (see below example).
Space for
supplementary
safety
information
symbols.
!SIGNAL WORD
Supplementary text, describing the kind and level of hazard/ risk seriousness.
• List of measures to avoid the herein described, hazard or hazardous situation.
• ...
• ...
Table of supplementary safety information symbols
The reference list below incorporates all safety information symbols used in this manual and their
meaning.
Symbol Meaning
General warning
Electrical hazard
Heavy weight, avoid overexertion
Explosive gases, explosive environment

2 Safety
8K-425 / K-436 Operation Manual, Version B
Symbol Meaning
Explosive material
Fire hazard
Harmful to life-forms
Hot item, hot surface
Device damage
Inhalation of substances
Chemical burns by corrosives
Fragile components
Wear laboratory coat
Wear protective goggles
Wear protective gloves
Heavy weight, lifting requires more than one person

2 Safety
9K-425 / K-436 Operation Manual, Version B
Additional user information
Paragraphs starting with Note transport helpful information for working with the device / software or its
supplementaries. Notes are not related to any kind of hazard or damage (see following example).
Note
Useful tips for the easy operation of the instrument / software.
2.5 Product safety
The SpeedDigester K-425 / K-436 has been designed and built in accordance with current state-of-
the-art technology. Safety warnings in this manual (as described in section 2.4) serve to make the user
alert to and avoid hazardous situations emanating from residual dangers by giving appropriate counter
measures.
However, risks to users, property and the environment can arise when the instrument is damaged,
used carelessly or improperly.
2.5.1 General hazards
The following safety messages show hazards of general kind which may occur when handling the
instrument. The user shall observe all listed counter measures in order to achieve and maintain the
lowest possible level of hazard.
Additional warning messages can be found whenever actions and situations described in this manual
are related to situational hazards.
!DANGER
Death or serious injuries by use in explosive environments.
• Do not store or operate the instrument in explosive environments
• Do not store chemicals in the vicinity of the device
• Operate the device in a fume hood with sufficient ventilation to directly withdraw fumes
!WARNING
Death or serious burns by flammable vapors.
• Remove all sources of flammable vapors
• Do not store flammable chemicals in the vicinity of the device

2 Safety
10 K-425 / K-436 Operation Manual, Version B
!WARNING
Risk of death or serious chemical burns by hot acid or peroxide fumes.
• Do not operate the system with faulty parts
• Check instrument setup for proper sealing before use
• Do not inhale process fumes
• Operate the instrument inside an active fume hood
• Do not move the instrument or parts of it during digestion
!CAUTION
Risk of minor or moderate cuts by sharp edges.
• Do not touch defective or broken glassware with bare hands
• Do not touch thin metal edges
!CAUTION
Risk of burns by hot machine parts and glassware.
• Do not touch hot parts or surfaces
• Let the system and inserted glassware cool down safely
• Do not move the instrument or parts of it when hot
NOTICE
Risk of instrument damage by liquids or mechanical shocks.
• Do not spill liquids over the instrument or its components
• Do not move the instrument when it is loaded with sample liquid
• Do not drop the instrument or its components
• Keep external vibrations away from the instrument
• Safely attach the instrument to the bench in earthquake prone regions
• Do not operate the instrument without the protection cover installed at the front
2.5.2 Warning labels on housing and assemblies
The following warning sticker(s) can be found on the housing or assemblies of the SpeedDigester:
Symbol Meaning Location
Hot item, hot surface Sticker / label, located on top of the housing and
at the racks
Do NOT put rack into side cooling position Label on 500 ml racks

2 Safety
11 K-425 / K-436 Operation Manual, Version B
2.5.3 Personal protective equipment
Always wear personal protective equipment such as protective eye goggles, protective clothing and
gloves. The personal protective equipment must meet all requirements of the supplementary data
sheets for the chemicals used.
!WARNING
Serious chemical burns by corrosives.
• Observe supplementary data sheets of all used chemicals.
• Handle corrosives in well ventilated environments only.
• Always wear protective goggles.
• Always wear protective gloves.
• Always wear protective clothes.
• Do not use damaged glassware.
2.5.4 Built-in safety elements and measures
Buchi glassware design
• All original Buchi digestion glassparts are made of high temperature and chemical resistant borosili-
cate glass.
• Acid fumes generated during digestion accumulate in the suction module
• The fumes must be safely withdrawn from the suction module via one or more hoses to a Scrubber
(e.g. Scrubber B-414) or via water jet pump into a sink or sufficient suction flow.
3rd party glassware
The quality of the material is an essential part of the safety concept of the SpeedDigester
K-425 / K-436. For the special rack (order no. 11055440), the following qualified vendors offer sample
tubes of sufficient quality grade to withstand the temperatures and the aggressive chemical digestion
agents:
Qualified vendor Tested sample tube(s)
Gerhardt 250 ml / 6100
Velp ø42×300 mm / A00000144
Foss 250 ml / 10014278
Heater
Each heating chamber is equipped with a safety overtemperature switch. In case of an emergency the
switch cuts off the power of the corresponding chamber and the 'Heating indicator' light.

2 Safety
12 K-425 / K-436 Operation Manual, Version B
2.6 General safety rules
Responsibility of the operator
The head of the laboratory is responsible for training his/her personnel.
The operator shall inform the manufacturer without delay of any safety-related incidents which might
occur during operation of the instrument or its accessories. Legal regulations, such as local, state and
federal laws applying to the instrument or its accessories must be strictly followed.
Duty of maintenance and care
The operator is responsible for the proper condition of instrument. This includes maintenance, service
and repair jobs that are performed and on schedule by authorized personnel only.
Spare parts to be used
Use only genuine consumables and spare parts for maintenance to assure good system performance,
reliability and safety. Any modifications of spare parts or assemblies are only allowed with the prior
written permission of the manufacturer.
Modifications
Modifications to the instrument are only permitted after prior consultation and with the written approval
of the manufacturer. Modifications and upgrades shall only be carried out by an authorized Buchi tech-
nical engineer. The manufacturer will decline any claim resulting from unauthorized modifications.

3 Technical data
13 K-425 / K-436 Operation Manual, Version B
3 Technical data
This chapter introduces the reader to the SpeedDigester K-425 / K-436 and its specifications. It
contains the scope of delivery, technical data, requirements and performance data.
3.1 Scope of application and delivery
All system configurations come with a limited set of accessories as a starter kit. Within a system family,
additionally available accessories (see section 3.1.2 and the following) can be used to easily recon-
figure your system to every configuration listed in section 3.1.1.
Parts that are required to change a system configuration:
• Rack
• Suction module
• Insulation plate (fireclay insert)
• Sample tubes
The scope of delivery depends on the ordered system configuration and can be checked according to
the individual delivery note and the listed order numbers.
Note
For additional information about the listed products, see www.buchi.com or contact your local dealer.
3.1.1 Available system configurations
SpeedDigester K- 425
Configuration
order number
Sample
positions Sample tube sizes Suction modules
110 – 120V 220 – 240V 5 6 250 ml 300 ml 500 ml Standard Condensate
trap H2O2
Module for
3rd party
tubes
1154251500 1154252500 • • •
1154251100 1154252100 • • •
1154251200 1154252200 • • •
1154251300 1154252300 • • •
1154251400 1154252400 • •*•*
* Third party sample tubes require special accessories such as the BUCHI “Module for 3rd party
tubes” and the matching rack / insulation plate. Tubes are not included in the set!
Note
The SpeedDigester K-425 is available in different versions for 110 – 120 V or 220 – 240 V mains supply.
Check your local voltage requirements and order accordingly!

3 Technical data
14 K-425 / K-436 Operation Manual, Version B
SpeedDigester K- 436
Configuration
order number
Sample
positions Sample tube sizes Suction modules
110 – 120V 220 – 240V 10 12 250 ml 300 ml 500 ml Standard Condensate
trap H2O2
Module for
3rd party
tubes
n.a. 1154362500 • • •
n.a. 1154362100 • • •
n.a. 1154362200 • • •
n.a. 1154362300 • • •
n.a. 1154362400 • •*•*
* Third party sample tubes require special accessories such as the BUCHI “Module for 3rd party
tubes” and the matching rack / insulation plate. Tubes are not included in the set!
Note
The SpeedDigester K-436 is only available for 220 – 240 Vmains supply. Check if a voltage converter
is necessary to adapt your local mains level before connecting the instrument!
3.1.2 Accessories for 300 ml sample tubes (for standard applications)
Item Additional info Order number Recommended quantity
to order
K-425 K-436
Set of sample tubes 300 ml, 4 tubes 037377 2× 3×
Suction module standard 6 place 11055849 1× 2×
Suction module condensate trap 6 place 11055865 1× 2×
Suction module H2O26 place, cpl. 11055853 1× 2×
Connectors to suction module Adapter and plug 11055367 1× 2×
EPDM hose Set for K-425 11056005 1× —
EPDM hose set Set for K-436 11056219 — 1×
Insulation plate (fireclay) Insertion, for 300 ml tubes 11055142 1× 2×
Rack 6 place, for 300 ml tubes 11055248 1× 2×
Glass caps (set of 4) OPTIONAL 040049 — —
Insulation cap OPTIONAL 11056024 — —
Sealing FKM (set of 6) Spare part 038122 — —
Sealing PTFE (1 pcs) OPTIONAL 022442 — —
Rubber GUKOs for H2O2suc. mod. Spare part set of 6 044495 — —
Filter funnel for H2O2suc. mod. Spare part set of 6 044494
Set circular spring and holder Spare part set of 6 11055984 — —
Bed-plate for 300ml racks OPTIONAL 11055943 — —

3 Technical data
15 K-425 / K-436 Operation Manual, Version B
3.1.3 Accessories for 500 ml sample tubes (for large sample volumes / at low nitrogen level)
Standard items Additional info Order number Recommended quantity
to order
K-425 K-436
Sample tubes 500 ml, single tube 026128 5× 10×
Set of sample tubes 500 ml, 4 tubes 043982 2× 3×
Suction module condensate trap 5 place 11055851 1× 2×
Connectors to suction module Adapter and plug 11055367 1× 2×
EPDM hose Set for K-425 11056005 1× —
EPDM hose set Set for K-436 11056219 — 1×
Insulation plate (fireclay) Insertion, for 500 ml tubes 11055143 1× 2×
Rack 5 place, for 500 ml tubes 11055327 1× 2×
Base for rack For 500ml tubes rack 11055612 1× 1×
Glass caps (set of 4) OPTIONAL 040049 — —
Insulation cap OPTIONAL 11056024 — —
Sealing FKM (set of 6) Spare part 038122 — —
Sealing PTFE (1 pcs) OPTIONAL 022442 — —
Interlock spring for 500 ml rack Spare part 11055385 — —
3.1.4 Accessories for 3rd party production, 250 ml sample tubes
Item Additional info Order number Recommended quantity
to order
K-425 K-436
3rd party sample tubes 250 ml n.a. 6× 12×
Suction module for 3rd party tubes 6 place 11055850 1× 2×
Connectors to suction module Adapter and plug 11055367 1× 2×
EPDM hose Set for K-425 11056005 1× —
EPDM hose set Set for K-436 11056219 — 1×
Insulation plate (fireclay) Insertion, for 250 ml tubes 11055877 1× 2×
Rack 6 place, for 250 ml tubes 11055440 1× 2×
Sealing FKM (set of 6) Spare part 038125 — —
Set circular spring and holder 6× Spare part 11055985 — —
Note
3rd party sample tubes are not available at Buchi. Please contact your local OEM vendor for these
type of tubes.

3 Technical data
16 K-425 / K-436 Operation Manual, Version B
3.2 Technical data
3.2.1 SpeedDigester K-425 / 110 – 120 V version
Technical data
Power consumption max. 1280 W
Temperature control range level 1 to 10 (70 – 580°C typically)
Connection voltage 110 – 120VAC
Input fuse T 10A L 250V
Frequency 50 / 60 Hz
IP degree of protection (two digits) IP 20
Explanation of protection level:
2 Protection provided by the enclosure against access
to hazardous parts (e.g., electrical conductors,
moving parts) and the ingress of solid foreign objects
with a diameter of > 12,5 mm.
0 No protection of the equipment inside the enclosure
against harmful ingress of water.
Insulation category II
Environmental conditions:
Pollution degree 2 (for indoor use only)
Temperature 5 – 40 °C
Altitude (above sea level) up to 2000 m
Humidity (curve parameter) Maximum relative humidity 80% up to 31 °C, then
decreasing linearly to 50% relative humidity at 40 °C
Dimensions in mm (W ×D ×H) 310 × 620 × 540
Net weight 12 kg
Rack (without glassware) 2,5 kg

3 Technical data
17 K-425 / K-436 Operation Manual, Version B
3.2.2 SpeedDigester K-425 / 220 – 240 V version
Technical data
Power consumption max. 1280 W
Temperature control range level 1 to 10 (70 – 580°C typically)
Connection voltage 220 – 240VAC
Input fuse T 10A L 250V
Frequency 50 / 60 Hz
IP degree of protection (two digits) IP 20
Explanation of protection level:
2 Protection provided by the enclosure against access
to hazardous parts (e.g., electrical conductors,
moving parts) and the ingress of solid foreign objects
with a diameter of > 12,5 mm.
0 No protection of the equipment inside the enclosure
against harmful ingress of water.
Insulation category II
Environmental conditions:
Pollution degree 2 (for indoor use only)
Temperature 5 – 40 °C
Altitude (above sea level) up to 2000 m
Humidity (curve parameter) Maximum relative humidity 80% up to 31 °C, then
decreasing linearly to 50% relative humidity at 40 °C
Dimensions in mm (W ×D ×H) 310 × 620 × 540
Net weight 12 kg
Rack (without glassware) 2,5 kg

3 Technical data
18 K-425 / K-436 Operation Manual, Version B
3.2.3 SpeedDigester K-436 / 220 – 240 V version
Technical data
Power consumption max. 2550 W
Temperature control range level 1 to 10 (70 – 580°C typically)
Connection voltage 220 – 240VAC
Input fuse T 10A L 250V
Frequency 50 / 60 Hz
IP degree of protection (two digits) IP 20
Explanation of protection level:
2 Protection provided by the enclosure against access
to hazardous parts (e.g., electrical conductors,
moving parts) and the ingress of solid foreign objects
with a diameter of > 12,5 mm.
0 No protection of the equipment inside the enclosure
against harmful ingress of water.
Insulation category II
Environmental conditions:
Pollution degree 2 (for indoor use only)
Temperature 5 – 40 °C
Altitude (above sea level) up to 2000 m
Humidity (curve parameter) Maximum relative humidity 80% up to 31 °C, then
decreasing linearly to 50% relative humidity at 40 °C
Dimensions in mm (W ×D ×H) 310 × 620 × 540
Net weight 15,5 kg
Rack (without glassware) 2× 2,5 kg

3 Technical data
19 K-425 / K-436 Operation Manual, Version B
3.3 Materials used
Materials used
Component Material designation Material code Hazards substances
Stainless steel Housing
Heating chamber
Heating element
Rack
Front panel under
thermostat(s)
Silicic acid Heating chamber SiO2, SiC
Ceramic fiber felt Heating chamber
Calcium silicate Insulation plate
Phlogopite mica Preheat cover
Plastic Front hood PBT
Suction hoses EPDM
Drip tray PP
Rack PPS
Sealings suction tube FKM/PFE
Hose coupling PP
Borosilicate glass 3.3 Suction tube
Digestion tubes
Aluminium Front bottom
Heat sink front
Sodium Capillary temperature
controller
Na 67/548/EWG:
R : 29
S : 12-23-37-65-103
Potassium Capillary temperature
controller
K 67/548/EWG:
R : 29
S : 12-23-37-65-103

4 Description of function
20 K-425 / K-436 Operation Manual, Version B
4 Description of function
This chapter explains the basic working principle of the SpeedDigester K-425 / K-436. It also shows
how the instrument is structured and provides a general functional description of its assemblies.
4.1 Functional principle
The SpeedDigester K-425 / K-436 is a special heating device to digest samples. It can generate max.
temperatures of 580°C typically. This allows e.g. acid digestion of organic sample components in a
concentrated sulfuric acid / catalyst mixture, known as 'Kjeldahl digestion'. During the processing the
sample material can reach peak temperatures of up to 370 °C at the bottom area of the sample tubes.
The maximum temperature of the sample highly depends on its composition i.e. the ratio of catalyst to
acid and can change during the digestion process.
Digestion process overview
3
2
1
4
Environmental
air inlet
dangerous vapors are drawn away
Condensing
zone
Infrared heating
Boiling / digesting
sample
Insulation plate
(fireclay insertion)
Acid vapor
outlet to
suction unit
(e.g. Scrubber)
(≈5 cm) Safety
zone
Processing steps:
• The infrared heating 1 generates high temperatures in the sample.
• Inside the sample tubes the digestion process takes place 2 while the acid is constantly boiling.
• Hot acid fumes rise into the condensing zone 3. After reflux, the acid flows back down to the
sample material, establishing a constant cycle.
• Residual fumes which escape the condensation zone are highly corrosive (!) and hazardous to life
forms. It must be withdrawn by a suction unit that deliveres sufficient flow (i.e. with a Scrubber
B-414 or a water jet pump) 4.
Note
The condensation should not take place inside the safety zone in order to prevent digestion of the
sealing rings. In case the condensation is too close to the suction module (e.g. due to very high
temperature settings) the digestion fumes may escape and the sample can dry out!