Scuba Force SF2 ECCR User manual

SF2 ECCR
OPERATION MANUAL

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SF2 ECCR OPERATION MANUAL
Table of Contents
Copyright / Warning 4
Safety 5
Preface 7
Chapter 1 –How the SF2 works 8
Chapter 2 –Soda Lime 11
2.1 Scrubber Duration Time 12
2.2 Storage 13
2.3 Influence of temperature on the Soda Lime output 13
2.4 Influence of exertion on scrubber duration time 13
2.5 SF2 scrubber duration time 13
Chapter 3 –Oxygen sensors 14
3.1 Functional principle and design of a sensor 15
3.2 Influence of pressure 16
3.3 Influence of moisture and water 16
3.4 Aging oxygen sensors 17
Chapter 4 –SF2 Components 18
4.1 Head 19
4.2 Midpart 19
4.3 Frame and accessoires 20
Chapter 5 –SF2 Assembly 21
5.1 Cylinder assembly 21
5.2 Bellow assembly 21
5.3 Scrubber and carbon fiber tube assembly 23
5.4 Battrey solenoid assembly 24
5.5 Sensor assembly 24
5.6 Loop assembly 26
Chapter 6 –Assembly accessories 29
6.1 Manual Add Kit & Off Board Gas 29
6.2 Assembly regulators, wing & harness 30
Chapter 7 - Calibration oxygen sensors 33
Chapter 8 –Predive Saftey Check 35
8.1 Check gas flow / gas direction 35
8.2 Positive- and negative test 36
8.3 Assembly Check 37
8.4 Predive Check 37
8.5 Prejump Check 38
Chapter 9 –After the dive 39
9.1 Disassembly of the SF2 39
9.2 Cleaning of the SF2 40
9.3 Disinfict 40
9.4 Transport and storage 41
Chapter 10 –Maintenance 41
Chapter 11 –Attachement 42
12.1 Checklist 42
12.2 Aditional Operation Manuals 43

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Congratulations on purchasing your SF2 ECCR rebreather. This unit has been
carefully manufactured to exact standards using high quality materials. When used
as directed, the SF2 ECCR will make diving more comfortable, enjoyable and
exciting.
The SF2 ECCR is intended for use by certified divers who are trained in the use of
rebreather systems or those divers who are under the direct supervision of a
qualified instructor.
Even if you are experienced in using rebreather systems, we strongly recommend
that you take the time to read these instructions. It contains many important safety
instructions and techniques that will help to extend the life of your rebreather.
On-line manual can be located on our website www.scubaforce.eu
For further questions, we can be contacted at:
SCUBA FORCE
Dive2gether.net Tauchsport GmbH
Reststrauch 197
41199 Mönchengladbach
Tel.: [phone]
Email: [email protected]
Der SF2 ECCR certified after EN 14143:20132-10 regulation (EU) 2016/425
Implementing test institute:
DEKRA
Testing and Certification GmbH
Adlerstrasse 29
45307 Essen
We would like to thank Dr. Frank Hartig, Dr. Andrea Köhler and Uwe Breidenstein for
providing texts, photos and graphics. And to all the photographers worldwide who
keep providing us with fantastic images, thank you.

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Copyright
All rights, intellectual property, and technical design reserved. No part of this
publication may be reproduced, distributed, or transmitted in any form or by any
means, including photocopying, recording, or other electronic or mechanical
methods, without the prior written permission of the publisher, SCUBA FORCE –
dive2gether.net Tauchsport GmbH.
Please read operating instructions carefully before using your rebreather.
Operating instructions are not a substitute for a general training manual for
rebreather units. You must be properly trained by an authorized SF2
instructor.
Warning, caution and notes
Pay particular attention to all information marked with warning, caution and note
according to the following symbols:
WARNING
A WARNING indicates a practice or situation which, if not avoided
could result in hazardous or unsafe practices that may result in severe
personal injury or death
CAUTION
CAUTION indicates a situation or usage
instruction that could damage
the product and result in injury to the user.
NOTE
NOTE emphasizes important points, notes,
and reminders.
WARNING
These operating procedures contain important
instructions for the correct use and care of your
new rebreather. It is therefore extremely
important that you take the time to read this
manual so that you can fully understand and
enjoy all of the features of your rebreather.
Improper use of your rebreather can result in
serious injury or death.
TECHNICAL HELP
If there is any ambiguity in this manual, or if you do not get sufficient answers from
your dive shop or diving instructor, please contact us

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Safety
Important Safety Instruction
This rebreather is intended for use by certified scuba divers who have completed a
rebreather course, or those who are being trained and supervised by a qualified
instructor.
WARNING
Follow all instructions and adhere to these safety measures.
Incorrect or improper handling of the rebreather can result
in serious injury or death.
WARNING
This manual is NOT a substitute for a rebreather training course
administrated by a qualified instructor. DO NOT USE a
rebreather until you have practiced and perfected practical skills,
including emergency skills, in a supervised environment and
under the supervision of an instructor who is certified by a
nationally recognized diving training organization and authorized
to train in SF2 rebreather use.
WARNING
Careless use of the SF2 can cause unconsciousness due to lack
of oxygen in any environment without prior warning signs.
Careless use of the SF2 at depths underwater greater than 6
MSW (meters of sea water) [20 FSW (feet of sea water)] can
cause unconsciousness without warning. Either of these
situations can cause serious injury or death. The SF2 is equipped
with a sophisticated electronic control system that enables a
properly trained user to avoid these situations. It is the sole
responsibility of the user to carefully monitor the displays on this
system while using the SF2 and to have a knowledge of response
measures in the event of a problem.

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Welcome to a new, quiet world of diving. With the acquisition of the SF2
ECCR you have taken another big step in your diving development.
New adventures are waiting for you. With a rebreather you can reach regions
that were previously unavailable to you.
The SF2 ECCR is one of the most popular and best-selling rebreather devices
worldwide. Straightforward design, high reliability, and simple pre dive
preparation and post dive follow-up are just a few of the points that have led
to the SF2 ECCR having a large fan base among sport, wreck and cave
divers. Whenever high reliability and special performance is required, the SF2
is used.
Soon you too will be one of the enthusiastic fans of rebreather diving in
general and the SF2 in particular.
But first you have to study and work. Your SF2 diving course will start
shortly and within a short period of time you will be confronted with many
new theoretical and practical knowledge and skills.
Rebreather diving is fun, but knowledge and skills are important to make it
safe. We believe the well-trained diver is one who is willing to commit to
continuous learning and safe training programs to perfect his/her skills.
Diving equipment, including a rebreather, are tools the diver must learn to
master - not the other way around.

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Chapter 1 - How the SF2 works
The SF2 belongs to the CCR rebreather category: Closed Circuit Rebreather This
describes a completely closed loop system in which only the metabolized oxygen
used (consumed) is added, this can be done manually (described as MCCR) or
electronically as with the SF2 ECCR.
The SF2 is an ECCR Electronic Closed Circuit Rebreather. The basic principle is
actually relatively simple and has been tried and tested for decades. The O2 content
in the breathing gas is measured via oxygen sensors - more on this later. If this
proportion falls below a pre-set value, oxygen flows into the system via an
electronically controlled solenoid valve (solenoid) until it again corresponds to the set
value.
What sounds simple in theory is influenced by various factors in practice, for
example increasing or decreasing pressure when descending or ascending.
In contrast to the open circuit system, the diver does not release any gas into the
environment when diving, so he breathes in a closed loop circuit which explains the
name. (If there is overpressure in the system, for example when surfacing, gas is
released into the environment even with a closed rebreather.)
Maintaining this circuit is important and must be checked before every dive. With the
SF2, the flutter valves, also called directional membranes, are located in the
mouthpiece. From the diver's point of view, i.e. with the device on his back, gas flows
from right to left.

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Our body consumes (metabolizes) the oxygen we breathe. This creates carbon
dioxide - CO2. We normally release this gas back into the environment when we
breathe. But since our breathing circuit is closed, the CO2 also remains in the
system. Hypercapnia, i.e. an increase in the level of carbon dioxide in the blood
(approx. 45 mmHg) can quickly lead to life-threatening situations, especially under
water. To prevent this from happening, the resulting CO2 is bound in a canister with
soda lime, which we will also go into briefly later.

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Since we can only
breathe in a circuit if
the gas has a flexible
volume in which to
collect it, in our body
that flexible volume is
the lungs. The SF2
has a "counterlung" in
the form of a bellows.
This type of
counterlung
configuration is unique
in the rebreather world
and has various
advantages: It is
compact, easy to
assemble, protected
by the lower carbon
tube. Last but not
least, an important
feature of the
counterlung is a huge
water trap at the
lowest point of where
the pressure relief
valve is located.
This describes the most important components of the SF2 and a rebreather in
general. The only thing missing is the gas addition supply. As mentioned at the
beginning, the consumed oxygen is added back to the system in pure form. The SF2
has an oxygen cylinder which, again from the perspective of the diver, wearing the
device located on the divers’ right side. Pure oxygen becomes "toxic" from a depth of
about twenty feet (six meters) and can no longer be breathed safely. So the oxygen
has to be diluted. In English this is called dilute and that is why the term diluent bottle
has established itself. Two gases are used as diluent in the SF2: On the one hand,
normal air and, on the other, trimix mixtures, i.e. a gas consisting of oxygen, nitrogen
and helium.
The diagram on the next page gives a good overview of the structure of the SF2

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SCHEMATIC REPRESENTATION SF2 ECCR

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Chapter 2 - The soda lime
The filtering out of the carbon dioxide (CO2) in the rebreather takes place with the
help of the soda lime through a chemical reaction. The soda lime reacts with the
CO2 in several stages and produces calcium carbonate (lime), water and heat. The
moisture and heat in turn enable the calcium reaction.
Put simply, CO2 and calcium hydroxide ultimately result in calcium carbonate. This
requires water (approx. 14-18% moisture) and a little sodium hydroxide (approx. 3%)
as a reaction accelerator.
Carbon dioxide reacts with water to form carbonic acid. Therefore, a certain basic
moisture content of the lime (as well as the moisture in the breathable air) is
necessary to start the reaction.
CO2+ H2O H2CO3(carbonic acid)
In a further step, the carbonic acid reacts with the caustic sodium hydroxide to form
sodium carbonate. This creates water again.
H2CO3+ 2 NaOH (Natriumhydroxyd)Na2CO3(Natriumkarbonat) + 2 H2O
Ultimately, the sodium carbonate reacts with the calcium hydroxide to form lime and the
sodium hydroxide is regenerated again.
Na2CO3+ Ca (OH)2(Calciumhydroxyd) CaCO3(Calciumcarbonat)+ 2 NaOH
The reaction substances water and sodium hydroxide are constantly renewed during
the process and are included in the reaction again. Only the calcium hydroxide is
consumed and therefore limits the absorption capacity (service life) of the lime. To
understand: The soda lime does not bind the CO2 in a gaseous state, e.g. Filter
cartridges in the compressor. Due to the completely different type of binding, filter
cartridges release the filtered CO2 back into the ambient air over time. The chemical
reaction of soda lime, on the other hand, leads to a complete conversion of the
gaseous CO2 from the air you breathe into a solid component, calcium carbonate.
No gaseous CO2 is present in fresh, wet or used lime.
The exothermic (= heat-releasing) chemical reaction generates heat. You can tell
that the scrubber is lukewarm after a dive, even in icy water. This heat prevents the
breathing gas from cooling down and significantly minimizes heat loss through the
lungs. The lime is used up in layers. The CO2 from the exhaled air flows into the
fresh soda lime and immediately reacts to calcium carbonate. If the lime has already
been used up a bit, the reaction zone (reacting layer of soda lime) moves further
forward accordingly. The soda lime is used up when the reaction zone nears the end
of the scrubber. The thickness of the reaction zone depends on various factors such
as the type of lime (particle size), reactivity (reaction temperature) and gas flow rate
(gas density).

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2.1 Lime duration time
The lime life of a scrubber depends on many different factors. The absorption
capacity depends primarily on the type or manufacturer, but storage, filling of the
scrubber, immersion conditions, temperature, exertion etc. Many factors have a
major influence on the nominal values of soda lime durations determined under
standard conditions.
2.2 Storage
To start the calcium reaction, moisture is required (CO2 reacts with water to form
carbonic acid). Therefore soda lime contains between 14-20% water. Incorrect
storage leads to drying out and thus to a loss of reactivity of the lime. Fresh lime, if it
is not stored airtight, will have dried out after 4 weeks at the latest. In addition, the
lime would bind the CO2 from the air and thus lose its absorption capacity. A filled
scrubber should therefore not be left standing around for too long. This is okay for a
repetitive dive on the weekend, but it should be replaced after 2 weeks at the latest.
2.3 Influence of temperature on the soda lime output
The soda lime output is particularly temperature-dependent. The lower the ambient
temperature, the worse the calcium reaction. This means that the soda lime filter
performance is significantly lower in cold water than in hot water. A canister filled and
used in warm Mexico waters could be used for 6 hours. The same canister filled and
used in 37 degrees Fahrenheit (3°C) cold mountain lake would be enough for 3
hours.
At 20 ° C e.g. the lime filtration rate is 100%, at 15 ° C it drops to around 80%, at 10
° C to around 65% and at 4 ° C to less than 50%.
In terms of temperature-dependent filtering performance, it is essential to note that
the filter rate per unit of time is meant here. The lime is not consumed faster in the
cold, but only reacts more slowly or the reaction zone becomes larger.
2.4 Influence of exertion on standing time
Another important point for the lime service life is physical activity and thus CO2
production. This can increase by up to tenfold with exertion and stress! Deep CCR
dives in cold water with stress and exertion are therefore high risk factors for a CO2
breakthrough or for hypercapnia. At rest, a person consumes about 0.3 l / min of
oxygen and converts this (depending on the respiratory quotient) into CO2. When
exercising, the O2 consumption or CO2 production increases to around 3.0 l / min,
top athletes can do even more. An average scrubber holds around 2 kg of lime, so it
has an absorption capacity of around 300 l of CO2 (approx. 150 l / kg). Usually one
produces an average CO2 production of 1.0 - 1.5 l / min during one dive. This means
that a fresh scrubber filling lasts for about 200-300 minutes. If the oxygen
consumption or CO2 production doubles due to exertion, the dive time is halved
accordingly. Depending on your personal consumption rate, diving conditions
(temperature, exertion, stress, etc.) and safety margin, you reduce the dive times.

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2.5 Endurance time SF2 Scrubber
According to the soda lime manufacturer, 1 kg of soda lime can bind approx. 110-
150 l of CO2. The approximate lime time can now be calculated using the
metabolism. The scrubber of the SF2 can hold up to 2.2 kg. The theoretical CO2
absorption capacity is about 330 l CO2. (2.2 x 150). Normally, one produces with 1-
1.5 l / min oxygen consumption or CO2 production, corresponding to physical activity
of about 100 watts. That means the theoretical lime filtering time is about 3.5 hours
(330 / 1.5 = 220 min).
CAUTION
The lime shouldn't under normal conditions Be used for more than
three hours. This is true both for repetitive dives as well as for single
dives corridors.
WARNING
Under extreme conditions, the lime Enormous service life. As part
of the CE test, the Lime at 50 meters ambient pressure, one
Water temperature of 4 ° Celsius and one Breathing minute
volume of 40 liters per minute tested: the lime service life is reduced
under these conditions on 60 minutes:
.

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Chapter 3 - Oxygen Sensors
Since the oxygen content in the breathing gas of rebreather systems has to be
measured reliably and permanently, oxygen sensors are used for this. To increase
the safety and accuracy of the O2 measurement, three oxygen sensors are built into
the SF2-CCR. The sensors are located in the head, where they are well protected
and yet easily accessible. The measured values are permanently transmitted to the
controller, which then regulates the setpoint via the solenoid if necessary. If a sensor
becomes defective, it can be voted out by the controller logic.
Nevertheless, two sensors are still available and the dive can be ended.
There are many different types of oxygen sensors, but galvanic oxygen sensors
have become established for use in diving for many reasons. These are built as a
complete unit and are thrown away and replaced when the internal components are
used up.
3.1 Functional principle and structure of a sensor
A galvanic oxygen sensor is a type of fuel cell that converts chemical reaction energy
into electrical energy (like a battery). This means that these sensors do not need an
external energization voltage, but are the power source themselves. Oxygen reacts
with the components of the cell (redox reaction) which creates a current that is
proportional to the prevailing oxygen partial pressure.
A cathode transfers electrons to the oxygen (reduction). The resulting hydroxide ions
(OH-) migrate in an electrolyte to the anode and there release the electrons again
(oxidation of the anode). This means that the anode is chemically changed or used
up. The electrons released in the reaction create an electrical current that is directly
proportional to the oxygen partial pressure. Practically all oxygen sensors measure
the partial pressure and not the percentage of the gas. This also makes sense there
the human body also reacts to the actual oxygen partial pressure and not to the
percentage in the breathing gas. Only if the ambient pressure is 1 bar and does not
vary between calibration and measurement, the percentage display (or fraction) is
equal to the partial pressure.

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3.2 Influence of pressure
Oxygen sensors usually measure the partial pressure of oxygen and not the percent.
The ambient air pressure therefore has a significant influence on the measurement
and calibration. At sea level there is an oxygen partial pressure of 0.209 bar. A
calibrated oxygen analyzer would show 20.9% accordingly. If the sensor were now
exposed to a pressure of 2 bar, it would display 41.8% (corresponding to 0.418 bar),
although the air composition has not changed.
In 5000 m, however, it would only show 10.45% (0.1045 bar). As a result, if the sea
level changes or if there are strong weather fluctuations, it must be recalibrated. Air
pressure fluctuations of 30 mbar due to changes in the weather lead to a
measurement error of around 3% (1 mbar pressure change corresponds to an error
of 0.1%). This means that the measurement of the oxygen content must always take
place under the same conditions as was previously calibrated. Most newer oxygen
analyzers, however, have
meanwhile a pressure sensor / barometer has been integrated so that the analyzer
corrects pressure fluctuations by itself.
Pressure fluctuations of this magnitude can also occur if the sensor is held directly
on a bottle valve or a mouthpiece for measurement. If the gas flow is too high (or if
gas flows directly onto the membrane), more gas flows onto the membrane than gas
can escape. This causes you "Back pressure" on the membrane, which is registered
by the sensor as an increased partial pressure. As a result, this leads to incorrect
measured values and can also lead to the destruction of the membrane.
A flow rate of 0.1-5 l / min neither affects the measurement accuracy nor does it
destroy the sensor membrane.

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In order to be able to compensate for various pressure fluctuations, a compensating
membrane is built into most sensors on the back. This is also necessary to cushion
volume fluctuations due to temperature changes. But that means that the
compensating membrane is always the same Pressure must be exposed like the
sensor membrane. If a sensor is installed in such a way that the compensation
membrane is not exposed to the ambient pressure, this not only leads to incorrect
measured values but also to the destruction of the sensor.
Oxygen sensors behave like a human body underwater. Since the main component
of the sensors is a liquid, they absorb gas when descending and release it again
when ascending.
To do this, they need time to stabilize. Rapid changes in pressure or temperature
can therefore lead to a "DCS" and influence the function of the sensor. Above all,
reducing the pressure too quickly can lead to the formation of bubbles in the
electrolyte. Bubbles in the sensor prevent the diffusion of the
Oxygen. The oxygen measurement stops and the output drops.
3.3 Influence of moisture and water
Moisture does not directly affect the accuracy of a good sensor. However, the
moisture in the gas takes up a certain proportion of the volume and thus also exerts
a partial pressure. The partial pressures of the remaining gas components are
reduced accordingly and the sensor shows less oxygen
increasing humidity (in the same environment).
However, extreme humidity or even condensation on the sensor surface significantly
impair the sensor function. Water on the sensor membrane prevents the diffusion of
oxygen so that the sensor becomes inoperable. In environments with extremely high
humidity, the membrane should be used before
Calibration or measurement can either be carefully wiped off with a soft, lint-free
cloth and / or the sensor held down during the measurement. This can cause drops
to form due to the surface tension of the water, which fall downwards. Also the slight
(!) Flow of dry gas from a diving cylinder across the Membrane can lead to drying of
the moisture.
Rebreather systems in particular have the problem of high gas humidity (due to
breathing) and condensation (due to the cold surrounding water). To prevent
malfunction of the sensors due to condensation, they are usually built into the head
in a special way. During calibration, the humidity would have an influence on the
result. But since you (at least When rebreather diving) calibrated with dry diving
gases, this problem is usually eliminated. However, due to the high humidity in the
circuit, calibration should never be carried out after a dive.

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3.4 Aging of oxygen sensors
Oxygen sensors begin to age from the point of production. The rapidity of aging, i.e.
the course of the chemical reaction and thus the consumption of the anode depends
on the surrounding environment Oxygen content and temperature. Usually, the
sensor output in air drops by around 5-10% per year. This means that the output of
an R-17 / R-22 sensor drops by approx. 1 mV per year in air (e.g. from 10 mV to 9
mV) or 5 mV in pure oxygen (from 50 mV to 45 mV). If oxygen sensors are stored in
pure oxygen, the service life is shortened by about a fifth. In the original packaging,
sensors age much more slowly, but they do not rest completely.
NOTE
The aging process of an oxygen sensor does not begin with
unpacking but with the date of manufacture!
WARNING
The SF2 sensors have an imprint:
DO NOT USE AFTER - followed by a date.
When the date is reached, the sensor must be replaced.
The use of an expired sensor can lead to dangerous situations.

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Chapter 4 - SF2 single components
FRONT VIEW
Accessoires:
Wing, Backplate, Harness, SPG´s
SF2 Components:
Loop, Controller, Fischercable
BACK VIEW
Accessories:
Diluent-and Oxygen Cylinder
SF2 Components:
Lower Carbon Fiber Tube (Counterlung); Upper
Carbon Fiber Tube (Scrubber); Head (Electronics
and Sensors)

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4.1 Head
4.2 Midpart
1
2
3
4
5
6
7
1. Sensor cover –underneath are the
oxygen sensors.
2. Sensor cable
3. Exhalation side –with oxygen
injection.
4. Inhale side
5. Battery box
6. Solenoid
7. Oxygen supply connection
1
2
3
4
1. ADV
2. ADV supply connection
3. Manual injection connection
4. Bellow / Counterlung

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4.3 Frame and accessoires
1
2
5
4
3
1. Backmount Frame incl. female pony
clamps
2. Manual Add Kit incl. Offboard Gas
3. Hose clamps and oxygen hose
4. Hose clamps and diluent hose
5. Breathing Loop with DSV
mouthpiece and connectors
Scrubber
Pony Clamp male
3 liter cylinders. The
picture shows G5 / 8
valves on both sides.
Within the EU, the bottles
for the oxygen side are
delivered with an M26x2
valve