Archive for the ‘Safety’ Category

Shallow Water Blackout

Sunday, February 8th, 2015

Shallow Water Blackout

Shallow water blackout, the sudden loss of consciousness due to oxygen starvation.

The sudden loss of consciousness due to oxygen starvation

If you’re like most Scuba Divers, what you likely remember about shallow water blackout – the sudden loss of consciousness due to oxygen starvation – is that it happens in shallow water while free diving. But given the growing interest in snorkelling and free diving, especially as a family activity, your working knowledge of this life-threatening malady needs to be more than just a vague memory.

The form of shallow water blackout that most of us are familiar with occurs primarily among breath-hold divers. A common technique when free diving is to hyperventilate before a dive – increasing the rate and depth of respirations. This “blows off” carbon dioxide in the system so that you start the dive with less carbon dioxide in your blood than you would otherwise. This technique allows you to stay down longer because it is elevated carbon dioxide levels in the blood that signal the brain that the body needs to breathe. By starting a breath-hold dive with less carbon dioxide in your blood, it takes you longer to build up carbon dioxide to the point where you feel the urge to breathe.

How Hyperventilation Causes Shallow Water Blackout:
The downside is that hyperventilation can bring on the condition of hypoxia, or lack of oxygen. The partial pressure of oxygen at sea level is .21 atmospheres (ATA). The brain requires a minimum partial pressure of oxygen of .10 ATA in order for you to remain conscious. Hyperventilation can drop you below that level.

Here’s what usually happens:
When a diver hyperventilates to reduce his body’s carbon dioxide level, he also slightly increases his oxygen partial pressure level to around .24 ATA. He then dives to a depth of 33 feet, doubling the pressure he is under, which also doubles the partial pressure of oxygen in his lungs to .48, according to Boyle’s Law. During the dive he extracts oxygen from his lungs, and slowly replaces it with carbon dioxide. By the time carbon dioxide accumulates sufficiently that the diver needs to surface, the oxygen partial pressure in his lungs is .15 ATA, but the diver is still at 33 feet. As he ascends, both he and the gas in his lungs are under less and less pressure, until he reaches the surface where, assuming an oxygen partial pressure of .15 ATA at depth, he would now have an oxygen partial pressure of .075 – less than that needed to maintain consciousness. Therefore, at some point before reaching the surface (usually between 10 and 15 feet), this diver would black out, instantaneously and without warning.

Diving and Snorkelling:

Is It Safe? What are the risks then, if any, of diving after snorkelling, or vice versa? Recreational snorkelling and free diving, because of the relatively short time spent at depth, do not result in any significant nitrogen build up in the blood or tissues. Therefore, there is little to no risk in diving after snorkelling.
However, the reverse is not necessarily true. It is well-known that tiny bubbles appear in many divers’ bloodstreams after diving. These bubbles are usually filtered from the blood as it passes through the lungs without causing any problems.

But if a diver with these micro-bubbles were to dive to a depth where the pressure forced these bubbles back into solution, and then ascend rapidly – as breath-hold divers do – these bubbles would come back out of solution, potentially as much larger bubbles that could result in symptoms of DCS. The depths at which the tiny bubbles would be forced back into solution are variable, but could occur at depths as shallow as 30 feet, well within the range of most snorkelers.

This potential risk can be easily eliminated by avoiding any deep free dives (below 15 feet) after scuba diving. So enjoy your snorkelling surface intervals, but remember to stay close to the surface and to wear a skin or T-shirt to protect your back from the sun.

shallow water blackouts

Padi Open Water Diver Course – Padi Neutral Buoyancy

Tuesday, November 4th, 2014

Padi Neutral Buoyancy -Instructor Development Skills.

Padi Open Water Diver Course – Neutral Buoyancy (Dive 3)

In the Open Water Diver course, Open Water Dive 3 neutral buoyancy skill underwater, the standard states: Become neutrally buoyant and hover by inflating the BCD orally.

The intent of the skill is to ensure that the student diver can use BCD oral inflation to attain neutral buoyancy in open water, as was mastered first in confined water.

You may also conduct this skill by:
1. having student divers demonstrate padi neutral buoyancy via oral BCD inflation (fin pivoting, for example). This demonstrates that the student can use controlled manual inflation underwater in the event of an inflator freeze or malfunction. Once the student is neutrally buoyant, then

2. having the student demonstrate hovering – using either BCD oral inflation, BCD LPI inflation, or dry suit inflation.

This offers a practical option in areas where student divers dive in dry suits that you can use now. The
amendment will be included in future editions of the Padi Open Water Diver Course Instructor Guide, Padi Neutral Buoyancy Skills.

Luxfer Carbon Composite Cylinders

Sunday, November 2nd, 2014

NOT FOR Underwater use of Luxfer full-wrap Type 3 carbon composite cylinders

Luxfer carbon composite cylinders Thursday, 01 May 2014 22:47

Luxfer carbon composite cylinders. Luxfer Gas Cylinders has received an increased number of inquiries about underwater use of full-wrapped Type 3 carbon composite cylinders. A Type 3 cylinder is a high-pressure cylinder composed of an all-aluminum liner fully overwrapped with layers of carbon fiber and fiberglass.

Rebreather Divers…
A warning notice from Luxfer about composite cylinder use

According to governing standards to which Luxfer’s Type 3 cylinders are designed and approved, these cylinders are not approved for underwater service and should not under any circumstances be used for SCUBA diving, closed-circuit rebreather devices, underwater gas storage or any related underwater applications. These limitations apply to both fresh water and salt water. Aforementioned standards include but may extend beyond ISO 11119, DOT-CFFC, HSE-AL-FW2 and EN12245.

If a Luxfer Type 3 cylinder has been used in underwater service, the cylinder should be immediately removed from service and presented to an authorized retest company for a thorough visual inspection and hydrostatic test.

For additional information, please contact Luxfer Gas Cylinders Customer Service at +1 (800) 764-0366.

PADI SIDEMOUNT DIVER COURSE CYPRUS

Friday, October 10th, 2014

Learn padi sidemount diver skills during your next course in Cyprus with Easy Divers Cyprus

SIDEMOUNT DIVER COURSE With the popularity of the Padi Sidemount course increasing, it’s only fair to give it a try and see how much fun sidemount diver course can be!

At Easy Divers Cyprus we have been teaching sidemount course for four years. Our number of Padi sidemount diver courses that train with sidemount equipment is increasing. We have a variety of different styles of sidemount diving BCD to suit all levels and sizes of divers. You shouldn’t just take sidemount harness without trying others.

During your course you will have a chance to see what type of sidemount gear that suits you.

Who should take this course?

Having scuba tanks on your back isn’t a requirement for exploring the underwater world. Many scuba divers have discovered the joy of mounting cylinders on their sides. Sidemount diving gives you flexibility and streamlining options. Plus, you don’t have to walk with heavy cylinders on your back – just enter the water, clip them on and go. Sound interesting?

Sign up for the PADI Sidemount Diver Specialty course with Easy Divers in Cyprus.

How can you start learning now?

Visit Easy Divers Shop in Protaras or email us to enroll in the Sidenount course and get your PADI Sidemount Diver or Tec Sidemount Diver Course. You need to read chapter one before meeting with your instructor to review key points. By studying ahead in your own time, you’ll be better prepared to start using your sidemount gear when you join your course.

If technical diving interests you, chapters two and three of your manual apply to the Tec Sidemount Diver course.

What scuba gear will you use?

You’ll want to use your own mask, fins, snorkel and exposure suit. Your PADI Instructor at Easy Divers will explain the sidemount equipment you’ll need, such as a BCD and harness configured for sidemount diving along with cylinders, each with a regulator and SPG.

Next Step

Configure yourself differently and earn your next certification:

3 Factors Ruining Your Scuba Education

Monday, September 22nd, 2014

3 Factors Ruining Your Scuba Education