Milestone SK-15 eT User manual

SK-15 eT
User Manual
MA209
MILESTONE
HELPING
CHEMISTS

Milestone Srl MA209-003 –SK-15 eT –User Manual
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Thank you for selecting our microwave system.
We are sure that you will be completely satisfied with the performance of this new unit entering your
laboratory. We invite you to read carefully this user manual and to keep it in reach for convenient and fast
consulting. The person who will be using this unit should have received an appropriate training from a
Milestone trained technician. For any possible clarification or any request for assistance please contact either
our Representative in your country:
or Milestone at the following address:
Milestone Srl
Via Fatebenefratelli, 1/5
24010 Sorisole (BG) Italy
Tel [phone]
Fax [phone]
Website www.milestonesrl.com
E-mail [e-mail]
ETHICS
The instruments commercialized by Milestone are intended for the use in strict compliance with
all applicable laws and in a manner that promotes public safety and/or linked to approved
scientific or medical research purposes.
Milestone does not endorse, encourage or promote the use of its instruments for any illegal
activities.
No liability for any consequences, direct or indirect, is accepted if the SK-15 eT is used in any
way in which the instrument is not intended to be used.
Publication date (gg/mm/aaaa) 15/10/2021

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1SAFETY RULES ................................................... 6
1.1 GENERAL INFORMATION...................................6
1.2 SAFETY IN OPERATIONS ................................... 6
1.3 ANY UNIT MANIPULATION ALLOWED ...............7
1.4 MAINTENANCE AND PARTS REPLACEMENT.......7
1.5 CUSTOMER SUPPORT.........................................7
1.6 OTHER HINTS ....................................................7
1.6.1 Working with accessories.......................................................7
2DESCRIPTION OF THE SYSTEM..........................8
2.1 OVERVIEW .........................................................8
2.1.1 Technical Specifications .........................................................8
2.2 SK-15 TECHNOLOGY ..........................................9
2.2.1 Components .........................................................................9
2.2.2 "Vent and reseal" system..................................................... 11
2.3 TEMPERATURE CONTROL ................................11
3OPERATIONS ...................................................13
3.1 OPERATIONS WITH MILESTONE SEGMENTED
ROTORS ...................................................................13
3.1.1 Sample weighing, reagents addition and vessel capping ........ 13
3.1.2 Cooling down and uncapping the vessels .............................. 17
3.1.3 Summary of the working parameters for SK-15 ..................... 19
4CARE AND MAINTENANCE INSTRUCTIONS .....20

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4.1 GENERAL CLEANING ........................................20
4.2 CARE AND MAINTENANCE OF IR (EASYTEMP)
SENSOR ...................................................................20
4.2.1 Cleaning of IR (easyTEMP) sensors ...................................... 20
4.2.2 EasyTEMP Calibration Test instructions ................................. 21
4.2.3 eT Calibration Test procedure .............................................. 22
4.2.4 eT protection cover ( SL0239C )............................................. 23
4.3 TFM COVER ......................................................23
4.4 PROTECTION SHIELD ......................................23
4.5 SAFETY SPRING ...............................................23
4.6 PRESSURE SCREW ...........................................24
4.7 ROTOR BODY ...................................................24
4.8 CLEANING OF TFM VESSELS ............................24
4.8.1 Cleaning procedure ............................................................. 24
4.8.2 “US EPA” recommended cleaning procedure ......................... 25
4.8.3 Microwave absorption.......................................................... 25
5GUIDELINES FOR MICROWAVE ACID
DIGESTION.............................................................. 26
5.1 INTRODUCTION TO THE MOST COMMONLY
USED REAGENTS IN MICROWAVE DIGESTION .......26
5.2 NITRIC ACID....................................................26
5.3 HYDROGEN PEROXIDE ....................................27
5.4 HYDROCHLORIC ACID .....................................27

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5.5 HYDROFLUORIC ACID .....................................28
5.5.1 Acid digestion ..................................................................... 28
5.5.2 Evaporation/Concentration................................................... 28
5.5.3 Complexation...................................................................... 28
5.6 AQUA REGIA ....................................................29
5.7 PERCHLORIC ACID ..........................................30
6REGULAR TESTS
ACCESSORIES/VESSELS/ROTORS...........................31
7SK-15 ET ROTOR TIPS AND TECHNIQUES .......32
7.1 GENERAL WORKING SPECIFICATIONS ...........32
7.1.1 Sample amount................................................................... 32
7.1.2 Volumes ............................................................................. 32
7.1.3 Temperature....................................................................... 32
7.1.4 Pressure ............................................................................. 32
7.1.5 Acid solutions...................................................................... 32
7.2 SK-15 ET SEGMENTS........................................32
7.3 COMPONENTS ..................................................33
7.3.1 Labeling.............................................................................. 33
7.3.2 Usage Log .......................................................................... 34
7.3.3 Examining the Spring –what to look for ............................... 34
7.4 APC REFERENCE VESSEL COVER......................34
7.4.1 APC reference vessel and cover as a set ............................... 34
7.4.2 APC tube positioning ........................................................... 35
7.4.3 Cleaning the pressure line.................................................... 35
7.4.4 Checking the pressure line for leaks ..................................... 35

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7.5 OPERATING TIPS .............................................36
7.5.1 Sample Weighing ................................................................ 36
7.5.2 Acid additions and digestion temperature ............................. 36
7.5.3 Small volume processing...................................................... 37
7.5.4 Vessels closure.................................................................... 37
7.5.5 Vessels opening (slow and gentle, avoid vapours) ................. 38
7.6 MAINTENANCE AND CARE ...............................38
7.6.1 Active cooling after every run............................................... 39
7.6.2 Clean and dry between runs ................................................ 39
7.6.3 Cleaning Safety springs ....................................................... 39
7.6.4 Cleaning vessels and covers................................................. 39
7.6.5 Surface Cleaning ................................................................. 39
7.6.6 Alternative Cleaning Procedures ........................................... 40
7.6.7 Cleaning vessels and covers from NOx contamination............ 41
7.6.8 Microwave absorption test ................................................... 41
7.6.9 NOx decontamination procedure .......................................... 42

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1SAFETY RULES
1.1 General Information
▪Please read carefully this operator manual before starting the system and follow its prescriptions
with the utmost care.
▪In case the system was delivered with additional accessories, also read carefully the instruction
manuals of such accessories.
▪Follow particularly the recommended instructions for Service and Maintenance.
▪This Operator Manual is part of the delivery, hence shall be always kept together with the
instrument on its working place.
▪It is imperative that every person operating this system has read and fully understood this manual.
▪The non-observance of the instructions contained herein or improper use may involve
damages/injuries not covered by product liability!
The national ruling and international safety norms in working environment shall in any case be observed
under user’s responsibility.
▪It is also user’s responsibility to keep constantly updated all safety norms ruling in the country or
operation.
Information= indicates important information/recommendation for the user.
Attention = means that the warning non-observance may cause damages to unit or properties.
Warning = means that the warning non-observance may cause injuries, even severe, to people.
1.2 Safety in operations
▪The unit shall be operated only according to its intended purpose.
▪The unit shall only be operated within the power limits set by technical specifications.
▪The unit shall be operated exclusively by specially trained people.
▪All electrical parts shall always be protected from wet and humidity.
▪The unit shall be kept clean.
▪Basic rules of chemistry will always apply. The basic rules of chemistry are valid also for chemicals
handling. Working with chemicals, always take into account all safety measures usually required
(e.g. lab coat, protective gloves, protective glasses/mask, exhausts hood, etc.)

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1.3 Any unit manipulation allowed
▪Constructive changes/modifications of the unit and its accessories are forbidden.
1.4 Maintenance and parts replacement
▪In order to guarantee the good functioning of the unit and user’s safety, all replacement parts
shall be exclusively original supplied by the manufacturer. The original parts are produced with
particular attention to quality and manufactory production.
1.5 Customer support
▪The warranty certificate and qc report are included in the documents supplied with the unit.
▪In case of unit reparation, please send us a service report with complete problem or damage
description.
▪For any question or spare parts order, please contact our representative in your country or directly
Milestone.
1.6 Other hints
▪Please take into account all the safety measures when filling in the vessels before the run or
when opening the vessel, once completed the run.
Don’t label the vessels. Discoloration may occur on protection shield with the consequent
damage.
1.6.1 Working with accessories
▪The complete vessel system must be treated with the utmost care and regularly tested. In case
of damage, the corresponding components must be replaced. Please pay particular attention to
the chapter “Care and maintenance instructions”.

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2DESCRIPTION OF THE SYSTEM
2.1 Overview
SK-15 High pressure rotor
The SK-15 (high pressure segmented rotor) contains 15 vessels for acid digestion of easy to medium-difficult
samples, such as soils, sludges, sediments, wastewater, food and feed, metals, alloys, etc. and of difficult
samples, such as coals, coke, ashes, rocks, plastics, lubrificants, pharmaceuticals, ceramics, etc.
Internal Pressure control can be provided optionally by an appropriate reference cover.
2.1.1 Technical Specifications
Min
volume
Vessel
volume
Max
temperature
Recommanded
working
temperature
Max
working
pressure
Recommanded Max
holding time at
220°C
5 ml
100 ml
300°C
240°C
100 bar
30 min
When exceeding the limit value, take into accounts that some parts could be stressed or damaged.
If you set the maximum routine conditions, a regular test of the vessel system is necessary. All
maximum values can be reached only by using material in perfect conditions. This includes as
well system maintenance, as usual in an analytical lab.

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2.2 SK-15 Technology
Milestone microwave rotor (MDR) technology provides analysts with unsurpassed performance capabilities
and the highest standard of safety in closed vessel. The vessels used in MDR rotors have no molded or
machined threads to be chemically attacked and weakened by hot vapours during vessel venting and
opening. This unique feature is an important factor in the durability and safety of Milestone vessels.
All vessels in MDR rotors are protected by a re-closing (vent and reseal) relief valve mechanism.
Vessels fitted into a MDR rotor body are sealed and have a relief valve functioning using a calibrated torque
wrench. The torque wrench ensures vessels are sealed for maximum operating pressure and will safely vent
when gases in excess are generated
2.2.1 Components
The rotor segment consists of a mould of high-density polypropylene charged with 30% of glass fiber.
The compact mould has the required strength to withstand the elevated pressure generated inside the
vessel during extraction.
The moulded rotor segment tolerates this pressure without any deformation and therefore with high safety.
Special plastic compression screws are located on the top of the segment.
Suitable pressure is applied to the safety spring holding the cover to the top of the vessel by tightening the
screws to the appropriate degree (10Nm).
The safety spring is the “heart” of the MDR technology. Due to its deformation, in case of overpressure
inside the vessel, it allows a safe and controlled release of gases inside the cavity and a perfect reseal when
the pressure returns under the operating limit.

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The safety spring (upper part)
The safety spring (bottom)
The cover has a flat bottom rim and perfectly fits the top rim of the vessel.
Warning
To avoid the wrong positioning of the safety spring on the top of the cover, the bottom of it is
marked with the word “down”.
The “down” side of the spring must be turned towards the cover.
Warning
Milestone recommend to replace safety springs after 500 runs or one year of work.
Warning
The springs MUST be completely dry from any acids and water drops.
Drops of liquids in contact with the internal spring, could generate a hotspot with consequently
damages of the whole spring.
Discolored, cracked, deformed, corroded of springs must be replaced
NEVER clean the springs with water, acids or solvents
Sealing between cover and vessel takes place on a very large surface area without any intermediate seal
ring, which could deteriorate in contact with hot vapors.

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Vessels and covers are made of TFM Teflon, chemically modified PTFE, which has a very dense structure
with smooth surface and low permeability to gases and vapours. TFM Teflon is chemically inert to most
organic solvents and combinations of them. It is a thermal insulator with a very high stability to temperature
extremes.
TFM Teflon is microwave transparent.
Safety shields are made of high resistant PEEK (Polyether ether ketone) and prevents lateral deformation of
the vessels.
2.2.2 "Vent and reseal" system
The drawing below clearly show the instantaneous release of overpressure due to the deformation of the
safety spring. The figure at left represents a vessel in normal working conditions. When pressure increases
over the maximum spring working pressure (figure in the center), the entire cover is allowed to lift up
because of the elastic deformation of the safety spring. The overpressure is instantaneously released thanks
to the large surface area. The larger the surface area the shorter the time required to release the pressure.
Once the pressure inside the vessel has returned within the vessel limit, the cover reseals the vessel,
permitting the operator to continue with the digestion without any loss (figure at right).
This is the unique operating principle of the microwave rotor technology of Milestone.
2.3 Temperature control
SK eT rotor is totally controlled by easyTEMP infrared sensor.
The sensor is positioned on the back side of the
bottom cavity in correspondence of the rotor ring.

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The easyTEMP contactless sensor directly controls
the temperature in all vessels through TFM vessels
bottom.
Warning
Please, refer to Ethos UP/Ethos EASY User manual for detailed info on the sensors.
eT protection cover
In order to protect the eT sensor lenses, a
protection cover (SL0239C) is placed on sensor
window. The conditions of the protection cover
must be periodically checked and, in case, it must
be replaced.
Warning
Please, refer to eT Calibration Test instructions for more details.

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3OPERATIONS
3.1 Operations with MILESTONE segmented rotors
When working with Milestone rotors, observe all safety indications and specifications. The user must be
familiar with the operations with vessel systems. In addition, follow the operating instructions reported in
the microwave system user manual.
3.1.1 Sample weighing, reagents addition and vessel capping
Introduce the rotor bottom plate into the microwave cavity
of the Milestone unit.
Milestone suggests to leave the rotor body always inside the
microwave cavity.
Place a Teflon vessel directly on the balance plate.
The weight of the Teflon vessel is about 115 g, therefore
most of the analytical balances may used for the purpose.
Tare the vessel and directly weigh the sample by placing it
inside the vessel.
Try to reduce as much as possible sample transfer, to avoid
contamination.
Add suitable reagents to the sample. When part of the
sample is left on the inner wall of the Teflon vessel, try to
wet it by adding acids drop by drop.
Introduce the Teflon vessel into the PEEK protection shield.

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The shields must be oriented with the bevel down
Warning
The wall surface of PEEK protection shield, as well as the outer wall of the Teflon vessel, must
be dry and clean. Damages may occur otherwise.
Gently swirl the solution to homogeneize the sample with the
acid.
Place the Teflon cover on the Teflon vessel.
Place the safety spring onto the Teflon cover.
Warning
The safety spring must be dry and clean.
Be careful to avoid to wet the inner parts of safety spring; if this should happen be sure to dry it
very well ! Damages may occur otherwise.

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Introduce the vessel into the polypropylene rotor segment.
Take the torque wrench and set the indicator to the “close”
position, as shown in the picture.
Put the polypropilene segment with the vessel onto the
workstation.
It’s possible to use the “manual” adapter (P/N 934063C) to
initially close the vessel screw.
Vessel must be anyway closed with the torque wrench!
Tighten the safety screw using the torque wrench.
Make long rotations instead of short ones and do proceed
slowly until you hear a clicking sound informing that the
vessel is properly close.

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Warning
Stop turning the torque wrench when a click is heard. The torque wrench may overload the safety
spring if further tightening is applied, compromising its correct work.
Place the segment into the rotor bottom plate.
Select the positions directly from the rotor page. The plate moves to
the selected position in order to facilitate the introduction of the
vessel.
Alternatively, switch on the "exhaust" (see picture) in order to start
the continuous rotation of the rotor plate.
Warning
Never force the rotation of rotor by hand. This could
damage the central PEEK adapter
Repeat the same procedure for all the remaining standard vessels.

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Warning
Never use vessel / vessels standing in a fix position. Always use the rotating rotor plate (rotor body).
Introduce the top rotor plate; the plate is fixed by the
connectors to each individual polypropylene segment.
Select a method from the software library (the method
should be marked with “eT”).
Start the digestion method, and introduce the number of
vessels that you have loaded on the rotor plate and wait the
end of the program.
Press start and wait the end of the digestion program. It’s
possible to monitor the internal temperature of each vessels
from the sample list / rotor window (see the Ethos UP user
manual for more details).
Wait for the end of the digestion program.
Warning
Open the vessels only when the internal
temperature is 80°C
3.1.2 Cooling down and uncapping the vessels
After the heating cycle has been completed, leave the vessels into the microwave cavity for the cooling time.
Set the cooling time (ventilation) in the terminal of the system, see Software manual.
Once the microwave program is completed, high temperature and pressure are reached inside the vessels,
according to the sample preparation procedure applied.

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It is therefore necessary to cool down the rotor before opening the vessels. The rotor may be air cooled
inside the ETHOS unit and in such case the cooling time is around 15 minutes. Once reached a temperature
less than 80°C the vessels can be opened.
Remove the vessels one by one, rotating the motor through the software
Remove the vessels one by one, rotating the motor through
the software.
Take the torque wrench and set the indicator to the “open”
position, as shown in the next picture.
Place the work station under a fume hood, and carefully
loosen the screw in the upper part of each individual
segment, by using the torque wrench.
Open the vessels very slowly, since a certain pressure may
still be present, depending on the sample type, even if the
temperature is as low as room temperature. Open the vessel
opposite to your position.
Remove the vessel from the polypropylene segment.
Slide the vessel from the protection shield and remove the
safety spring.
Carefully lift up the vessel cover and rinse the lower part of
the TFM Teflon cover with distilled water, collecting the same
inside the vessel.