test Flashcards
what’s the most important rule in scuba diving? ⚠️⛔️
never hold your breath 😮💨🫁
what happens when you hold your breath? 😶🥱😮💨
it blocks you airways and your lungs over expand (lung rupture) forcing air into the blood stream and chest cavities causing paralysis and death 💀
what’s a reverse block? 🔄
when expanding air gets trapped in a body air space
why shouldn’t you use decongestants? 🤧🥴
they can wear out and stop ascent by causing reverse block
what should you do if you get reverse block?
descend a metre and wait for the air to work its way out
why shouldn’t you dive with a cold or allergy? 🤧🤒🥴
it can cause congestion making it difficult or impossible to equalize
how do you equalize your lungs?
by simply continuously breathing, litch you don’t need to do anything 😮😮
why shouldn’t you use ear plugs? 👂
they create air spaces which you cant equalise
how do you equalise your ears mask and sinus on ascent?
air works it’s way out naturally, you don’t need to do anything 🥽
what’s a squeeze?
when you don’t adjust for increasing pressure compressing a body airspace and there is greater pressure outside the airspace than in it
what’s an ear squeeze?
pressure pushing your eardrum and surrounding tissue inward
how do you know if it’s a sinus squeeze?
you feel discomfort in your cheeks, central forehead and along the nose
what happens if it’s a mask squeeze?
a pulling or sucking sensation on your face
what happens if you don’t equalize your mask?
unequalised mask can cause facial bruising 😣
how do you prevent squeezes?
add air to air spaces to keep the pressure equal with the outside pressure
how do you equalise your… ?
• nose
• sinus
• mask
- pinch your nose and blow or wiggle your jaw and swallow
- pinch your nose and blow or wiggle your jaw and swallow
- gently blow bubbles through your nose
why cant swimming goggles be used?
as they don’t cover the nose you cant equalise
when should you equalize?
every meter, before you feel discomfort
what should you do if you’re struggling to equalise?
ascend until you can’t feel discomfort and try again, if unable to stop the dive 🛑
what injuries occurs if you dive without equalising?
fluid accumulating in the middle ear and eardrum rupture which causes severe vertigo
the deeper you go the _________ you use your air.
faster
what fraction of the original time would your air last at 30m?
1/4
what happens to air as you go further down
the pressure compresses the molecules making the air denser and harder to breathe, breathing in this air takes more energy
If an object weighs less than the water it displaces, it _____. This is
_________ buoyancy.
- floats
* positive
If an object weighs more than the
water it displaces, it _____. This is
____________ buoyancy.
- sinks
* negative
If an object weighs the same as the
water it displaces, it neither floats nor sinks. This is _________ buoyancy.
•neutral
what’s buoyancy
an upward force acting on an object in water, the force being equal to the weight of the water displaced
why is salt water more buoyant?
salt water has minerals (salt) dissolved in it so a given volume weighs more than fresh water.
what does the weight system do?
has just enough weight to offset positive buoyancy and make it neutral
what inflating and deflating your BCD do?
increases and decreases your volume - how much water you displace.
why does breathing affect you buoyancy?
when you inhale you chest expands displacing more water and when you exhale your chest contracts.
what does buoyancy allow you to do?
• Descend and ascend at a slow, controlled rate.
• Stop a descent or ascent and maintain your depth with little effort.
• Float comfortably on the surface.
• Save energy and avoid harming
sensitive aquatic organisms by swimming neutrally buoyant and
controlling your movements.
• Maintain the underwater visibility by helping you not stir up the bottom.
• Enjoy one of the sensations unique to diving - “weightlessness.
When I descend, my buoyancy tends to ________.
When I ascend, it tends to ________.
decrease, increase
what are the 3 primary considerations when buying scuba equipment?
- suitability
- fit
- comfort
what are the 4 secondary considerations for scuba equipment? (idrk if u need this)
cost and features
serviceability
colour and style
accessories
how should you care for your equipment?
- inspect it to make sure of proper operation, wear and damage
- rinse in fresh water
- don’t leave in direct sunlight for long periods of time
- some equipment required professional servicing
what are the 3 benefits of the buddy system?
- practicality- assist eachother before, during and after each dive
- safety- help prevent problems and assist in an emergency
- fun- have someone to share dive adventures with
what do dive buddies do? 👯♀️
- plan dives
- help each other gear up
- remind each other of dive time and depth limit
- assist if there a problem
- assist each other with what they want to do on the dive
how should your mask fit? 🤿
snug but not overly tight
why are snorkels used in scuba? 🤿
to preserve air supply when near the surface
what side does your snorkel go? 🤿
left because your regulator is on your right
what do fins do? 🏊♀️
provide a large surface area for your legs to push against so you move more efficiently through the water
what are the two fin types?
adjustable strap
full foot
what are the two primary considerations when buying fins?
fit and blade size
what four equipment systems combine to make a scuba kit?
BCD
regulator
cylinder
weight system
what should you consider when buying scuba kit?
size preferences and the dive adventures that appeal to you
what 5 components make up a BCD?
inflatable bladder cylinder band LPI (low pressure inflator) overpressure/quick exhaust valves weight system
how should u store a BCD
partially inflated so the sides don’t stick together
what are the 5 stages that make up a regulator
hub, supplies air to all of the components regulator alternate air source supplies air to BCD the spg/computer - air u have left
what do the first and second stage of a regulator do regarding pressure
the first stage rises the pressure to 7-10 bars above the surrounding pressure and the second stage (the regulator) brings it down to the surrounding pressure
where does your primary second stage come from (the one you breathe from)
over your right shoulder
where is your alternate air source?
in a quick release in the triangle zone
where does an SPG go
under your left arm secured
what two components make up a cylinder?
- the cylinder itself
* the valve
what do the markings on the cylinder tell you?
- serial number
- working pressure
- hydrostatic test date
how to take care of your cylinder
• never leave it unattended
• don’t leave it standing, lay it down BCD up
• always have it secure on transport
or boats
how do you maintain your cylinders?
- have the cylinder pressure tested (hydrostatics test)
- annual visual checks
- close and open the valve gently
- never leave the cylinder completely empty to stop moisture for getting in
- store the cylinder standing where it won’t get knocked over
- keep it out of high heat so the pressure won’t get affected
what’s the most important feature in a weight system? 🏋️♀️🏋️♂️🏋️
a quick release as it allows you to drop the weights and float in an emergency
what’s trim?
the right distribution of weights
when should you inflate your BCD
when entering the water
return to the surface add or vent air in small amounts when underwater
how should you kick
the flutter kick, kick from your hip with very little bend to the knee
how do you inflate your BCD orally
press the button you would usually use to deflate and blow into it releasing the button between breaths
water is magnified by 1/3, water is 800 times denser than air, light gets absorbed in roygbv
bwraf blue wales really are friendly
bcd weight review air final check
