BÜHLMANN Decompression 01 User manual

USER MANUAL BUEHLMANN DECOMPRESSION 01
Your Bühlmann Decompression 01 is a watch for demanding sportsmen and -
women. Please read this user manual to get acquainted with the functioning of your
watch and take note of all disclaimers, caution items and security recommendations.
Disclaimer
Whilst the Bühlmann Decompression 01 is a diver watch according to traditional
watchmaking industry standards, it is not a dive computer nor a professional diving
watch according to ISO or any other official - private or public - certification agency
or institution. It should UNDER NO CIRCUMSTANCE be used as the only diving
instrument or to replace a dive computer. It should also UNDER NO
CIRCUMSTANCE be used as the only diving instrument for managing diving at
altitude over 700m above sea level and to decide whether to fly or not to fly after a
dive.
Diving is an inherently dangerous sport and exposes one-self to the risk of
permanent injury and/or death. GFF Suisse SA t/a Watch Angels and Cronatec LLC
will not accept any liability for injury or death caused whilst engaging directly or
indirectly in any diving activities with the use of the Bühlmann Decompression 01
watch.
There are no warranties or guarantees, either expressed or implied that the
information contained in this user manual or our website www.watchangels.ch site is
accurate, correct, updated or reliable.
You are responsible for using your own good judgement. You should be in good
physical condition, enjoying good health, have a certification from a recognized
training organization and sufficient knowledge to participate in every dive. Your level
of fitness and experience is an essential requirement for your dive plans. You should
dive within your limits at all times, protect yourself from natures elements and stay
hydrated to maintain your physical condition.
Caution 01: Use a diving computer
Despite being, horologically speaking a professional diving watch, the Bühlmann
Decompression 01 should never replace a professional diving computer. Only dive
computers collect and calculate all the elements you need for secure diving. The
main goal of the Bühlmann Decompression 01 watch is therefore to help the diver
understand and apply the modern security instruments for free diving and UNDER
NO CIRCUMSTANCE to replace or being used as a diving computer.

Caution 02: No dive without serious planning
Planning your dive is essential for your personal security. Depending on the way you
are breathing, on the air pressure in your air tank, on temperature, currents etc. you
will develop a sound feeling how long your dive trip can last. From this complete
cycle you must deduct your way down to the ground, the bottom time, the ascent
time and all the security stops you find on the bezel for the maximum depth of your
dive excursion.
Let’s make an example:
You want to go down to a maximum depth of 40 m. Your experience tells you that
normally your air reserve lasts for 40 minutes. Always keep a reserve! Descent will
take let’s say 6 minutes. The ascent control on the watch indicates that you cannot
ascend faster than 10m per minute. So, coming up takes another 4 minutes. The
three necessary security stops for a 40 m dive will sum up 55 minutes. This of
course cannot work. The total necessary time by summing the necessary steps is of
65 minutes and your air reserve is of 40min. Consequently, you must replan your
adventure completely, organize a bigger air reserve and a secure ascent to enjoy a
reasonable bottom time.
Caution 03: Screw down the crowns
The main cause of damaged dive watches is water entering the watch and damaging
the movement. To avoid this risk, you must screw down all the three crowns of your
Bühlmann Decompression 01 tightly before entering the water and lock them with
the bezel push-lock system. Never open a crown once you are under water!
Only the decompression bezel can be turned during a dive. As a security measure
the decompression bezel only turns clockwise. This means that, for your safety, it
can only extend but never shorten your security stops.
The Bühlmann Decompression 01 is a self-winding automatic mechanical watch. For
precautionary reasons, even if an automatic watch winds under-water, be sure not to
stay near to the end of its power reserve when you start diving by rewinding the
watch before every dive.
1. DECOMPRESSION STOPS TURNING BEZEL
Why a decompression stops turning bezel?
Decompression tables allow divers to plan the depth and duration for dives and the
required decompression stops. On your Bühlmann Decompression 01 watch the
decompression table is executed as a circular calculator.
The information on the bezels for 20, 30 and 40m is taken from Bühlmann's 1974
calculation disk. Since there is limited space for data on the watch, the

decompression data on the bezels for 20, 30 and 40m are only given for the longest
possible bottom times of the Bühlmann decompression calculation disk.
Attention! The breathing gas will therefore most likely not be sufficient for a dive
with this bottom time
1.1 Description of the information on your watch (Fig. 1)

Example valid for the depicted 40m bezel
(a) Luminous dot at 12 o’clock (same for all bezels)
Once the minutes hand aligns with this dot when you are measuring your
decompression stop time, it means your decompression time has been reached and
you can proceed to the next decompression stop.
(b) Depth 40 m
This indication helps you to identify the correct bezel for your planned dive. For
example, if you decide to dive to 40m you will mount the 40m decompression bezel
on your watch.
(c) BT 40 min
BT stands for bottom time. If you dive to 40m the maximum bottom time (meaning
your planned work time on the ground) is 40 minutes. All security stops are
calculated with this long stay at 40 m deep.
(d) RG K, L (same for all bezels)
If you do repetitive dives over a limited period, your body will be saturated with
additional gas for each dive. With each further dive it is therefore necessary to
calculate longer safety stops. Repetitive groups (designated with capital letters) are
used for this purpose. The repetitive groups K and L result in the longest time
surcharges. As a result, on your bezel you have the longest security stops previewed
by the original 1974 Bühlmann calculation disk.
(e) 0-700 m ASL (same for all bezels)
This indication stands for 0-700 m altitude above sea level. On the Bühlmann
watches we calculate with decompression stops on sea level or not higher than 700
m. Attention: if you dive in higher altitudes like mountain lakes, you cannot use the
bezels of the watch but must use specialized decompression tables which calculate
longer security stops.
(f) Security decompression stops 1 (9m), 2 (6m), 3(3m)
These number shows you the sequence of the decompression stops, 1 is the first, 2
the second and 3 the third stop. Left of the number you see the depth of the stop.
The number below the depth in meters shows you the total time of stand still at the
indicated depth in minutes: 5 minutes at 9m, 15min at 6m and 35min at 3m.
1.2 How to use the decompression turning bezel
Your Bühlmann Decompression 01 comes with three exchangeable decompression
bezels for dives at 20, 30 and 40m. They can be exchanged by unscrewing the 4

screws on the side of the bezel using the provided screwdriver. Do not use any other
screwdrivers to avoid the risk of damaging the screws.
Each bezel should ONLY be used for a dive at the specified depth (or shallower)
indicated on the bezel (a.) and at sea level or at maximum 700m above sea level
(b.) If you use a bezel specified for a specific depth for a dive to deeper depth, the
information will be wrong and if it is used for managing a dive this could lead to
permanent injury or death.
Attention!
Before each dive, check that you have mounted the correct bezel for the dive.
To calculate your decompression stops on a dive you must stop at EACH
decompression stop indicated on the bezel and, at each stop, bring the
corresponding depth/time marker in front of the minutes hand by turning the bezel.
You then must stay at the given depth until the minute hand reaches the luminous
dot on the bezel. When the minute hand reaches the luminous dot, you can then
proceed to the next decompression stop and at repeat the same process.
Example 1: dive to 40m (Fig. 2)
The 40m bezel shows a MAXIMUM bottom time of 40min and three security stops.
1) Choose the 40m bezel and fix it to your watch
2) You will see on the bezel that there are 3 decompression stops markers for
such dive: 1 = -9m (5min); 2 = -6m (15min) and 3 = -3m (35min)
3) When you reach stop 1 on your ascent, you stop and set the -9m/5min
decompression stop marker (b) on the bezel in front of the minutes hand by
turning the bezel. The 5 minutes will have elapsed when the minute hand
aligns with the luminous dot on the bezel (a). Only then you can proceed to
the next stop
4) When you reach stop 2 and 3, repeat the same process, using
decompression stop markers (c) and (d)

Example 2: dive to 30m (Fig. 3)
The 30m bezel shows a MAXIMUM bottom time of 75 minutes and three security
stops.
1) Choose the 30m bezel and fix it to your watch
2) You will see on the bezel that there are 3 decompression stops markers for
such dive: 1 = -9m (7min); 2= -6m (15min) and 3 = -3m (42 min)
3) When you reach stop 1 on your ascent, you stop and set the -9m/7min
decompression stop marker (b) on the bezel in front of the minutes hand by
turning the bezel. The 7 minutes will have elapsed when the minute hand
aligns with the luminous dot on the bezel (a). Only then you can proceed to
the next decompression stop
4) When you reach stop 2 and 3, repeat the same process, using
decompression stop markers (c) and (d)

Example 3: dive to 20m (Fig.4)
The 20m bezel shows a MAXIMUM bottom time of 105 minutes and two security
stops.
1) Choose the 20m bezel and fix it to your watch
2) You will see on the bezel that there are 2 decompression stops markers for
such dive: 1 = -6m (3min) and 2= -3m (31min)
3) When you reach stop 1 on your ascent, you stop and set the -6m/3min
decompression stop marker (b) on the bezel in front of the minutes hand by
turning the bezel. The 3 minutes will have elapsed when the minute hand
aligns with the luminous dot on the bezel (a). Only then you can proceed to
the next decompression stop
4) When you reach stop 2, repeat the same process, using decompression stop
marker (c)

2. THE ACUAL DIVE TIME (ADT) INDICATOR
Why the actual dive time indicator?
The actual dive time indicator measures our total elapsed dive time to make sure
that you do not exceed the maximum time you can stay underwater. Never stay
longer under water as your expected air reserve! If necessary, organize a spare air
tank. Actual dive time is measured with the aid of the internal turning bezel of the
watch.
How to use Actual Dive Time indicator (Fig. 5)
The actual dive time (ADT) can be calculated by using the inner turning bezel (a).
The inner turning bezel is operated by the crown on the top right (b) which is marked
with ADT.
To measure your ADT, you proceed as follows:
1) Before starting your dive, you place the triangle (c) on the inner turning bezel
in front of the minutes hand
2) During the dive you can at any moment read your ADT by reading the elapsed
time on the scale in front of the minutes hand
In the example on Fig. 5 the ADT is 20 minutes.
Attention do not operate crown b under water! This could cause the water-resistance
of your watch to be compromised and your security put in danger.

3. THE LOCK-UNLOCK SYSTEM FOR THE CROWNS AND HELIUM VALVE
Why a security system for the crowns and valve?
The security system is important to make sure that a wrong manipulation or any type
of shock does not accidentally move the minutes hand and the inner turning bezel.
This would change the ADT and decompression information and compromise the
water-resistance of the watch. The consequences of this could put your health or life
at risk.
Attention: Never operate the lock-unlock system under water!
How to use the lock and unlock system (Fig. 6)
The security system is provided by the bezel. It is the bezel which locks or releases
the crowns and valve. You must operate the bezel to use the crowns to set the time
(and the position of the minutes hand), to set the ADT turning bezel and to open or
close the helium valve.
To unlock the crowns and valve you proceed as follows:
Step 1: Rotate the bezel clockwise until the luminous dot (a) aligns with the 1h index
(b)
Step 2: When you reach this position press down the bezel
Step 3: With the bezel pressed down, turn it clockwise until it comes to a stop at
position (c) (block point (c) is after a ca 10° rotation)
Step 4: The crowns and valve are now unlocked and can be operated by first
unscrewing them
To lock the crowns and valve proceed in the reverse sequence:
Step 1: First screw back in the crowns and the valve in case they have been
unscrewed
Step 2: Turn the bezel anticlockwise until the luminous dot (a) is aligned with the 1h
index (b)
Step 3: The bezel will automatically lift blocking the crowns
Step 4: Turn the bezel to the initial position or in a position of your choice

Bezel exchange
To remove the bezels, use only the screwdriver provided and unscrew the 4 screws
(d). Remove the bezel and replace it with another one and screw the 4 screws (d)
back-on
4. THE FLY-NO FLY INDICATOR
Why a fly-no-fly indicator?
Flying after scuba diving is one of the more widely known risks to divers. This issue
comes up frequently in the diving world because divers want to take full advantage of
their vacations and get the most diving time in while they can.
The main reason for this is the pressure inside the airplane’s cabin. It lessens as you
reach altitude. When you’re flying in a plane right after diving, the increase in altitude
would result in a drop in of pressure, a risk for decompression sickness.
The nitrogen can form bubbles in your body which can be painful and possibly fatal.
Waiting the correct amount of time before flying will reduce the nitrogen in your body.

As a general rule it is recommended to wait at least 24 to 48 hours before flying after
doing any type of diving. This rule covers all types of dives and adds extra time as a
safeguard.
How to use the fly-no-fly indicator (Fig. 7)
The fly-no-fly indicator (a) is located in the dial aperture at 9’o clock.
The indicator is a disk with red, orange, and green segments. The disk is operated
by the center crown when unscrewed and pulled in position 2 (see paragraph 5
below).
To operate the indicator, you proceed as follows:
1) After the dive you turn the disk to red by turning the crown
2) When the indicator on your watch turns to green you are safe to fly*
*Attention: The no-fly time might be different from individual to individual and from
one type of dive to another. When the indicator shows green it means that min. 36h
have elapsed since the end of your dive. When the indicator shows orange, it
means that between min. 12 and max 24 hours have elapsed since the end of
your dive and that it might not be safe to fly. Orange therefore means NO FLY.

5. HELIUM ESCAPE VALVE
Why a helium escape valve?
When working at great depths, professional divers stay in a diving bell for days,
breathing a mixture of gases containing a high proportion of helium. The pressure is
gradually increased to reach the pressure at the working depth.
The divers, still inside the bell, are then lowered to the working site. They leave the
bell to carry out their work. Once their work is complete, they re-enter the bell, which
is then raised to the surface. Pressure is then returned to atmospheric levels, and
this is when the escape valve must be opened. The helium molecules diffuse and
penetrate the material of the gaskets. The quantity is sufficient to push out the crystal
during the return to atmospheric pressure. To avoid this, the Bühlmann
Decompression 01 is equipped with a valve helium escape valve.
How to use the helium escape valve? (fig. 8)
The helium valve should be used only in a decompression chamber. It should never
be operated underwater so as not to compromise the water-resistance of the watch.
In its normal position (phase a.), the helium escape valve is perfectly watertight
thanks to the gaskets (1), but it is not functional since it is screwed down.

During the decompression phase in the decompression chamber, unscrew the crown
of the valve (phase b) in order to release the mechanism. As the interior pressure
becomes greater than the exterior pressure, it pushes the gasket (2) out of its
seating, thus releasing the gas. Once the pressure is equalized, gasket (2) returns to
its original position, pushed by the spring. This operation is automatically repeated
several times during the decompression phase. Once atmospheric pressure is
reached, screw down the crown of the valve to close it.
6. ASCENT CONTROL (Fig. 9)
When you ascend from the bottom depth of your dive trip, your organism must
constantly lower its gas pression and transport the additionally absorbed gas to the
lungs.
This process needs time. If you do not give your body the necessary time gas might
form gas bubbles in your body that can cause disastrous damages in your organs.
To avoid this risk, you should NEVER ASCEND FASTER THAN 10m PER MINUTE.
Your depth gauge should never go up more than 10m in 60 seconds.
To control ascent speed, you can use the seconds counter at 3 o’clock (a). When the
hand has made one full 360° turn it means that 60 seconds have elapsed.

7. SETTING THE TIME, THE FLY NO FLY INDICATOR AND MANUAL
WINDING (Fig. 10)
For these operations you use the center crown. To set the crown in position 1, 2
and 3 you first unlock the crown (see paragraph 3), then you unscrew the crown, and
then:
a) To manually wind the watch: pull the crown in position 1 and turn anti-
clockwise
b) To turn the fly-no-fly indicator: pull the crown in position 2 and turn
clockwise
c) To set time: pull the crown into position 3 and turn the hands in the desired
position

8. ADDITIONAL NOTES
9.1 The case-back (Fig. 11)
The shape of the case-back gives a 5-degree inclination to the watch for optimized
readability and increased wear comfort.
The formula pt tol i.g. = (p amb/b) + a which is engraved on the case-back is the
decompression algorithm developed by Dr. Bühlmann. It has a decorative purpose to
honor his legacy.
9.2 Service
In order to ensure that your watch remains watertight, we recommend that you have
it checked every two years.
9.3 Recommendation
For safe diving we recommend you follow the advice and directives of official and
recognized diving institutions like the PADI, NAUI, CMAS, SSI, the Divers Alert
Network (DAN) or other official and accredited institutions. Always use the
recommended dive plan schemes and register your dives in your log
Zürich, 26.10.2022