MARES CXR-I : How-To Guide : Page 10

•

PART

II

8.2. ALTITUDE

Atmospheric

pressure

is a function of

altitude

and of

weather conditions.

This is an

import

ant

aspect

to

consider

for diving,

because the

atmospheric pressure surrounding

you has

an

influence

on

uptake

and

subsequent

r

el

ease

of

nitrogen.

Above a

certain altitude,

the

decompression algorithm

has to

change in

order

to

account

for the effect of the

change in

atmospheric pressure.

CXR-I

aut

omatic

all

y

adapts

the

algorithm

by

sensing

the

ambient

pressure

every 20

seconds

even when it

is

turned

off

.

8.5. ALARMS

CXR-I can

alert

you of

pot

entiall

y

danger

ous

situations.

There are six

different

alarms:

•

8.

DIVING WITH

CXR-I

-

Ascent

rate alarm;

Exceeding

a safe ppO /MOD;

2

CNS =75%;

Missed

decompression

s

t

op;

Lo

w tank

pr

es

sur

e/RG

T

< 3

min;

Low

battery

during the

div

e.

8.1.

A FEW WORDS ABOUT

NITRO

X

Nitrox is the

term

used to

describe

br

eathing

gases made

of

oxygen-nitrogen

mixes

with

an oxygen

percentage higher

than 21%

(air).

Because

Nitrox

contains less nitrogen

than

air,

there

is

less nitrogen

loading on

the

diver’s

body at the

same

depth as

compared

t

o

breathing air

.

However, the

increase

in oxygen

conc

entr

ation

in Nitrox implies an

increase

in oxygen

partial

pressure

in the

breathing

mix at the

same

depth. At

higher

than

atmospheric partial

pressures,

oxygen can have toxic

effects

on

the

human

body. These can be

lumped

into

two

c

at

egories:

8.3. LOGBOOK

From

the home

screen, press

the

LOG

butt

on

to

access

the

logbook.

CXR-I can

record

the

profiles

of over

1000

hours

of diving, at a

sampling rate

of

5

seconds.

The

information

can be

tr

ansf

err

ed

to a

Smartphone

(MySSI

app, via

bluet

ooth),

PC (Dive

Organizer software, Bluetooth

or USB

cable) or Mac (DiversDiary

software, Bluetooth

or USB cable). In addition, CXR-I can

sho

w

most of the

information

directly on the

display

.

On the main page of the logbook you will see

a

listing of all dives, including date, time the

div

e

started,

depth and dive

time.

By

pressing

SELECT

you will

access

the

det

ails

of the dive, and from

here

you can view

the

depth profile with

either

the

temperature or

tank

pressure

data by

pressing

PROFILE.

-

Sudden effects

due to oxygen

partial

pressure

over 1.4bar. These are not

r

elat

ed

to the

length

of the

exposure

to high

partial

pressure

oxygen, and can vary in

terms

of

the

exact level of

partial pressure

they

happen

at. It is

commonl

y

accepted

that

partial

pressures

up to 1.4bar are

tolerable, and

se

v

er

al

training agencies advocate maximum

oxygen

partial pressures

up to

1.6bar.

Long

exposure effects

to oxygen

partial

pressures

over 0.5bar due to

repeated and/

or long dives. These can affect the

c

entr

al

nervous system, cause damage

to lungs

or

to

other

vital

or

gans.

8.5.1.

ASCENT

RATE

As soon as depth

decreases

CXR-I

activ

at

es

the

ascent rate control algorithm

and

displays

the

calculated

value both

numericall

y

and

gr

aphic

all

y

.

-

CXR-I

keeps

you safe with

respect

to

these

two

effects

in the following ways (as long as

it

is set to

either

AIR

or

NITRO

X

):

•

Against

sudden effects:

CXR-I has an MOD

alarm

set for a

user-defined

ppO max. As

2

you

enter

the oxygen

concentration

for

the

dive, CXR-I shows you the

c

orr

esponding

MOD

for the defined ppO max. The

def

ault

8.4.

DIVE

PLANNER

From

the home

screen, press

and hold

the

PLAN

button to

access

the dive

planner

.

This function allows you to plan your next

div

e.

In

case

you dived

r

ec

entl

y

,

you can

enter an

additional surface

interval

between

now

and

when you intend to dive: the

residual nitr

ogen

load will be

adapted ac

c

or

dingl

y

.

CXR-I will

consider

all active

gases

and set

gr

adient

f

act

or

s,

listed for

reference

at the top of

the

screen.

Hit the

SELECT

button then use

the

and buttons

to define the

additional

surf

ac

e

interval in

15-minute increments.

BACK

and use the and

buttons

to

scr

oll

through

the no

decompression

limits for

all

depths,

in 3m

/

10ft

increments,

up to

the

MOD

for the gas in use. If you wish to see

what

would

happen

if for a given depth you

e

xt

ended

your dive time beyond the no

decompr

es

sion

limit,

press

the right

button, labelled

DEC

O

.

Use

the to

increase

your dive time

and

see what your

corresponding decompr

es

sion

obligation would be.

Press

BACK

to

return

t

o

the no

decompression limits.

If CXR-I

determines

an

ascent rate higher

than set limits, the fast

ascent alarm is

triggered:

an

audible alarm

goes off,

the

arrows

on the left side bar turn

red

and

the

message

SLOW DOWN

is

displayed

in

the

middle of the

screen

of the

screen

(Fig. 8).

This

persists

until the

ascent rate

is

r

educed

to below the

pertinent

limit. The limits

are

dependent

on the

current

depth as

f

ollo

w:

2

value of ppO max from the factory is

1.4bar

.

2

This can be

adjusted

to your

pr

ef

er

enc

e

between

1.2 and 1.6bar.

Please refer

t

o

section

2.1 for more

information

on how

t

o

change

this

setting.

If CXR-I is set to AIR,

the ppO max is set to 1.4bar by

def

ault.

2

Against long

exposure effects: CXR-I

“tracks”

the

exposure

by

means

of

the

CNS %

(Central Nervous

System). At

l

e

v

els

of 100% and

higher there

is risk of

l

ong

exposure effects,

and

c

onsequentl

y

CXR-I

will

activate

an

alarm

when this level of

CNS% is

reached.

CXR-I also

warns

y

ou

when the CNS level

reaches

75%. Note

that

the CNS% is

independent

of the value of

ppO max set by the

user

.

•

Depth

in

m

Speed

in

m/min

Depth

in

f

eet

Speed

in

ft/min

> 50

m

20

> 165 ft

60

30 – 50

m

15

100

–

165

ft

45

10 – 30

m

10

30 – 100 ft

30

<

10m

5

<

30ft

15

2

11

W

ARNING

A

rapid ascent increases

the risk of

decompression sicknes

s.

NOTE

-

Alarms are both visual and

audible,

as

described

in detail

bel

o

w

.

-

If you are in any

graphic

display

mode

(compass,

dive profile, map viewing

or

tissue

graph) when an

alarm

is

triggered,

you will be kicked out of that mode

and

back to the

standard numeric

display

.

-

Ascent

rate alarm

has priority

o

v

er

other alarms

if they are

triggered

simultaneousl

y

.

NOTE

We do not

recommend

diving at

altitudes

above 3700m

/

12100ft. If you do,

set

CXR-I to

BOTTOM TIMER

and find

appropriate altitude

dive

t

abl

es.

W

ARNING

When in bottom timer mode, all

warnings

and all

alarms

are

OFF

aside for the

lo

w

battery

alarm

.