Frequently asked questions

 

What is IANTD?

Born in 1985, IANTD (International Association of Nitrox and Technical Divers) is a scuba diving training agency which develops programmes for recreational, technical and free diving activities. It was the first agency to introduce the recreational diving community to the technology of EANx and the first to offer training programmes in all aspects of technical diving.

IANTD offers wide and exhaustive training possibilities from free diving, a broad range of recreational diving programmes to advanced technical diving courses and dive professional training. The flexibility and extensiveness of its curriculum allows satisfying the most demanding divers and underwater world enthusiasts. Through very high training standards, IANTD aims at training individuals to become confident, competent, knowledgeable and responsible instructors and divers.

IANTD has Licensed offices worldwide which are able to issue certification cards to give its members a better service.

You need Nitrox to go deep. Is that right?

Actually no, it’s actually quite the opposite. Oxygen becomes increasingly more toxic the deeper it is breathed. In fact 100% Oxygen when used as a decompression gas by technical divers is considered seriously unsafe to breath deeper than 6m. It follows then that Nitrox having a greater percentage of Oxygen than the 20.9% of Oxygen found in air is also increasingly more toxic than air when breathed at depth.

If you can’t dive deeper with Nitrox, why use it?

While you can’t dive deeper with Nitrox than air, you can stay longer at the same depth within the depth limits of Nitrox. During a dive a diver absorbs dissolved nitrogen from the gas being breathed into the bloodstream and body’s tissues. This nitrogen can cause serious problems if not allowed to escape from the diver’s body on ascent. Dive tables (and dive computers) give a diver an indication of what is generally considered safe exposures to nitrogen at various depths. If there is less nitrogen in the breathing gas, then those limits are longer as there is less nitrogen exposure (due to the fact that the Oxygen is metabolised).

Is it true that cave diving is the world’s most dangerous sport?

No, the sport worldwide with the most fatalities while being played is in fact crown green bowling! Surprising? Not so surprising really when you consider the average age of the participants! Of course, it is ridiculous to make one sport appear safe just because another has a higher statistical risk of death or injury.

So the question is really, “Just how dangerous is cave diving?”

The answer is that there are certainly occasional fatalities, but the reputation of cave diving as being the pastime of the suicidal is very much based on the statistics from the early days of cave diving from the 1970’s through to the mid 1990’s. Modern equipment and more importantly advances in training and procedures through detailed accident analysis have contributed almost entirely to a massive drop of incidents in relation to the number of individuals enjoying the sport.

What is Nitrogen Narcosis?

Nitrogen narcosis or inert gas narcosis is the often pleasant but very dangerous feeling that arises from the absorption of nitrogen at depth. The effect as the name implies is narcotic. Also known as ‘rapture of the deep’ or the narcs, nitrogen narcosis can lead to a false sense of security and the feeling of being superhuman. The ability to complete simple tasks and the diver’s ability to stay focused are lessened increasingly with depth until a point where the diver is pretty much diving drunk, a condition that can be extremely dangerous to both the diver and the buddies that are relying upon him. The pleasant effects of Nitrogen Narcosis can quickly turn to anxiety and paranoia when faced with the smallest of problems.
The only way to treat nitrogen narcosis is to ascend until the effects diminish.

Why dive with Rebreathers?

Rebreathers offer a new experience and /or challenge and enable you to get much closer to marine life as there are fewer bubbles and less noise. Rebreathers have practical benefits such as greater dive duration, longer no stop time, more efficient inert gas management and more efficient use of your breathing gas as well as the physiological benefits of Nitrox diving. In addition, if you are planning to dive in colder waters the warmer breathing gas gives some benefits.

Why must you have Nitrox knowledge to dive Rebreathers?

Mixes other than Air (20.9% Oxygen and 79% Nitrogen) are generally used with Rebreathers and therefore the diver must understand the considerations of using Nitrox for recreational diving.

What are the basic differences between closed and semi closed circuits?

Semi Closed Circuit Rebreather (SCR) units such as the Dräger Dolphin and the San-o-Sub Azimuth use a pre-selected, constant flow, Nitrox mix that is chosen to match the Maximum Operating Depth (MOD) of the planned dive. Venting of excess gas occurs periodically during the dive and ascent.

Closed Circuit Rebreather (CCR) units dynamically mix 100% Oxygen with a diluent to form a breathable gas mix. For entry-level Rebreather diving, the diluent used is air and this combines with 100% Oxygen to form a Nitrox mix. For deeper dives the diluent gas may be Heliox or Trimix, depending on the Rebreather manufacturers’ recommendations. This mix varies continuously with depth to maintain a pre-selected PO2 set point. Venting of gas only occurs on ascent due to expansion.

What are the main differences of Rebreathers compared to a normal diving set?

The diver no longer experiences a change in buoyancy when breathing in and out. Furthermore the diver’s buoyancy can now affected by up to three independent gas volumes, namely the diver’s lung / Rebreather counter-lung, the BCD or wing and the dry suit. These all have to be considered, particularly in an emergency.

What are the main considerations of Rebreathers when compared to a normal diving set?

Considerations are the same as open circuit air, Nitrox or mixed gas plus a few more. These additional factors include increased risk of hyperoxia, hypoxia, and hypercapnia. The diver must take a meticulous approach to both diving equipment and diving practises when diving with any form of Rebreather. Consequently adequate consideration should be given to: using a stable dive platform; avoiding task loading during all stages of the dive including the preparation of the unit; avoiding adverse diving conditions such as dives with “saw-tooth profiles”; ensuring good buoyancy control especially during ascent and descent.

Why is there a maximum depth limit for Nitrox mixes in Rebreather diving?

The entry level Rebreather training for both SCR and CCR Rebreathers provided by the recognised training agencies generally qualify Rebreather users to dive Nitrox mixes to 40 metres, with minimal decompression diving. The 40 metre limit is based on the risk of carbon dioxide retention (hypercapnia) and the pre-disposition because of this to CNS Oxygen toxicity.

What is mixed gas?

The term mixed gas is generally used to mean a helium based gas, either Trimix (Oxygen, Helium and Nitrogen) or Heliox (Oxygen & Helium).

Can I dive with mixed gas in my Rebreather if I have an open circuit mixed gas certification?

Whilst there are many common factors in open circuit and Rebreather mixed gas diving there are also significant differences. The bailout and emergency strategies can vary considerably, partly due to the huge difference between gas efficiency when using the Rebreather (on loop) and when having to bailout to open circuit.

To what depths can a mixed gas certified Rebreather diver go to?

To a maximum of 80 metres or to the maximum depth allowed by his/her qualification, whichever is the shallower depth. Typically divers with Rebreather full mixed gas qualifications will therefore be able to go to 80 metres. Divers holding Rebreather Normoxic/Intermediate mixed gas qualifications are normally limited to approximately 60 metres by their qualification.

Why is the maximum set point limited to 1.3 bar for the target operating depth?

A maximum set-point of 1.3 bar is recommended for closed circuit Rebreathers with electronically selectable set points to ensure a safety margin against over-shoot of the PO2 – particularly critical if the descent is too fast. However, a set-point of 1.4 is allowed for decompression to facilitate the efficient off- gassing of inert gas providing this does not exceed 80% CNS toxicity.

In addition, breathing inspired PO2 above this level for extended periods significantly increases the risks of CNS Oxygen toxicity. It should be remembered that relatively high percentages of CNS can be achieved when mixed gas is used for relatively longer dives with extended decompression schedules on high PO2. Consequently, it may be wise to choose a lower set-point than 1.3 when conducting such dives.

What is the generally accepted maximum PO2 that can be used with Rebreathers on dives?

  • SCR:
    • 1.5 bar during the dive
    • 1.6 bar during decompression stops
  • CCR:
    • 1.3 bar during the dive
    • 1.4 bar during decompression stops
    • 1.6 bar during flush and open circuit bailout

Can 100% Oxygen be used for open circuit bailout from a CCR Rebreather?

CCR diving to 40 metres with minimal decompression diving, as per entry level Rebreather qualifications, does not necessarily warrant the use of open circuit Oxygen for emergency purposes. However, if the mixed gas certified Rebreather diver chooses to have access to any or all gases carried, whether on-board or off-board, appropriate safeguards should be utilised to avoid inadvertent gas loss and incorrect selection of gas for maximum operating depth.

What is generally the maximum PO2 that can be used by Rebreather divers for open circuit bailout?

1.6 bar for mixed gas qualified Rebreather divers. 1.4 bar for entry level Rebreather divers. The bailout plan of a mixed gas Rebreather diver will possibly involve the use of multiple bailout gases. Choice of the bailout gases should be carefully planned in line with the diver’s qualifications and not exceed the PO2 of 1.6 bar.

Is there a maximum decompression for the open circuit diving buddy?

The maximum decompression limit of the dive plan should be based on the most conservative case taking into consideration the qualifications and experience of both open circuit and Rebreather divers.

I’ve seen a lot of articles about Rebreather divers being solo, can you explain?

In accordance with generally recognised procedures solo diving is considered to be outside normal recreation sport diving parameters and not permitted. Owing to the possible increased risk of hypercapnia, hypoxia and hyperoxia, it is particularly important to ensure good buddy monitoring. Unfortunately, many of the early Rebreather fatalities occurred while diving solo – it is impossible to say whether these events could have been avoided. It is essential that the buddy be appropriately qualified, experienced and properly briefed prior to the dive.

Why should a Rebreather diver always pre-breathe the Rebreather before diving?

Pre-breathing the Rebreather warms up the absorbent material towards its optimum working temperature before the dive begins. Pre-breathing also allows the diver to confirm that the Rebreather is functioning correctly whilst you are safely out of the water. Very importantly, pre-breathing is your only check for CO2 contamination before your dive. If you get a CO2 hit whilst pre-breathing on the boat or land you will survive. Underwater might result in a different outcome!

Why should the diluent cylinder of a CCR be full at the start of a dive?

The diluent may be used for suit inflation and be performing the function of bailout gas. It is therefore good practice to have the maximum bailout available to the diver in case a bailout situation and/or if the need for the buddy to perform a controlled buoyant lift arises. In these cases a typical 2 or 3 litre, 232bar cylinder will be barely sufficient. Hence, it is recommended to use of an additional (off-board) bailout cylinder when diving deeper than 15 metres.

In the case of mixed gas, the CCR diver may choose to use an independent off board source so that the mixed gas is not used for suit or BC inflation, since the poor thermal qualities of helium make it less suitable for suit inflation. The situation is more flexible in relation to the O2 cylinder since normally very little O2 is used during a dive. Occasionally, 232 bar fills are not always available. However, since there is typically only a 2L or 3L Oxygen cylinder, it is prudent to maximise the O2 available to the diver .In particular in the case of a leaking mask or diluent flushes at depth or even leaks in the loop then the cylinder can be depleted quickly.

Many Rebreather divers consider it good practice to carry a small cylinder of Oxygen or >70 % Nitrox that can be plugged into the CCR Rebreather as back up should the main O2 supply be lost for any reason.

Can a mixed gas Rebreather diver safely dive with a Trimix open circuit diver?

Yes. Care should be taken to ensure that decompression schedules and bailout plans are similar to facilitate efficient buddy diving but with good planning it is perfectly possible. Obviously, it is preferable for two mixed gas Rebreather divers to dive together using similar diluent mixes and similar decompression tools. In this case, the decompression and bailout run time schedules will be similar and dive planning is simplified.

Can a mixed gas Rebreather diver dive with a Nitrox Rebreather diver?

This is also possible, but it does have its limitations. Decompression and bailout schedules may vary slightly. Care should be taken in the planning to ensure that they are similar and do not impair buddy diving. This is also simplified if both divers are using the same decompression tool.

Can a mixed gas Rebreather diver dive with an open circuit air diver?

Again, this is quite possible, but as the depth and duration of the dive increases the planning considerations increase. However, as the pair will be limited by the maximum depth of either 35 metres or 50 metres for the open circuit air diver the problem is minimised and can be overcome by careful planning.

It should be remembered that the lower molecular mass of helium means that the characteristics of on and off gassing of the Rebreather diver may vary from that of the air diver. As a consequence the decompression schedule for similar bottom times will differ. The main differences are likely to be that the mixed gas Rebreather diluent diver will have stops at deeper depths and a longer decompressions schedule for a similar bottom time than the air diver. This will become more pronounced as the depths and bottom times become more adventurous. The mixed gas diver may accrue deeper decompression stops than the air diver. On staying together the air divers shall consequently accrue a larger decompression penalty over and above their own dive plan. The key to this is as always to be meticulous in dive planning and to adjust bottom times accordingly.

Why should SCR diving be a progressive step towards CCR diving?

It is clearly not a requirement to learn SCR diving prior to CCR diving, however, certain aspects of Rebreather diving are generic to all Rebreathers:

  • the need to prepare the equipment properly – especially regarding the scrubber duration
  • positive & negative checks
  • understanding the loop
  • the lack of buoyancy changes with breath control
  • the static lung loading experienced
  • the need to monitor hyperoxia, hypercapnia, and hypoxia
  • the familiarity with PO2 monitoring

Clearly each unit needs specific training and experience, but the learning curve for a SCR diver to become a CCR diver is less steep than from an open circuit diver to a CCR diver – as many experienced CCR divers and instructors will confirm.

How many dives can a Rebreather diver perform each day?

The entry level Rebreather diver will be governed by the normal considerations of Nitrox diving such as CNS loading, UPTDs and decompression considerations. Mixed gas use in sport diving is still in its infancy. Mixed gas computers will allow the diver to conduct more than one mixed gas dive per day. However, it is good practice to limit deep diving to one excursion per day.

Are Rebreather divers subject to similar surface interval requirements as ordinary divers?

Yes. No different to the principles of planning Nitrox or mixed gas diving.

Can I use PC programmes for Rebreather dive planning?

Yes – “commercially” recognised PC based dive planning tools can be used. Appropriate instruments (computers or depth-timers) should be used to ensure compliance with the dive plan in the normal manner. When carrying out mixed gas diving it is strongly recommended that multiple decompression tools are carried – for example at least one computer could be carried in addition to a dive timer/depth gauge with (cut) hard tables showing run times for back-up. The dive planning must also take into consideration the experience, interests, equipment and ability of the buddy as in normal dive planning.

How do tables and computer fit together?

In each case the dive plan should be discussed and the most conservative dive plan agreed between the divers in accordance with the dive pairing guidelines provided. It is worth noting that some computers and PC based decompression tools will have differing decompression stop depths. An example of this is that many computers have stops based at 12, 9, 6 and 3 metres. Some programmes and computers will have much deeper but short stops within their schedules. This must be carefully considered when planning a dive. It is much better to have both divers of a buddy pair using the same decompression tool.

How does the buddy check differ for a buddy pair with different gear configurations?

Review / modify the buddy check procedure to accommodate the Rebreather layout especially the shutdown operation of the mouthpiece. The buddy check should ensure the buddy is aware of the risks and knows the appropriate emergency procedures. For example; the Rebreather user should state the possible additional problems with a Rebreather (hypoxia, hyperoxia, hypercapnia) and brief / demonstrate the appropriate action for each.

I have lost my certification card. What do I do?

You can contact IANTD Egypt for a replacement at the current price list cost.

I want to advertise my company on the IANTD Egypt website. What sort of options are available for me?

Contact the office to receive information about the prices.

Am I insured for sport diving?

You have to check your travel insurance and if necessary contact your insurance provider to make sure that you are covered for the type of diving you are doing and for the depth you plan to go to.

Does a recreational diver require dive insurance?

I can’t think of a technical or cave diver that I know that does not have insurance against accidents caused directly by diving, basically hyperbaric chamber insurance. I would advise strongly that a diver owes it to themselves and their families to be properly insured. I say this from witnessing firsthand the denial that an uninsured, but clearly injured diver goes through while being persuaded to go to a chamber. While denial, is a common symptom of DCS it is far easier to coax an insured diver to the chamber who has only to worry about the inconvenience of the chamber ride as opposed to the significant financial burden it can bring to bear. Extensive dive insurance covering all levels of diving can be arranged. Both DAN and PADI offer respected insurance.

Some people are mistakenly under the impression that they are covered by household or credit card insurance. Be sure to check the fine print and particularly the depth limits. An elderly British diver in 2005 faced a bill of 20,000 GBP from a DCS incident in Egypt, because his household insurance had a depth limit of 40m.

Am I insured for technical diving?

Again please check with your insurance provider that you will be covered for this activity and for the planned depths.

How do I get diving professional insurance?

There are many types of insurance available for both recreational and professional divers. DAN offers different levels of both as do several other insurance providers.

I am already qualified with another diving agency. How do I crossover to IANTD?

The crossover is not a complicated step. Normally a crossover requires a maximum of three to four days. The intent is to show the correct use of IANTD Standards plus the explanations of the differences in training.

What happens if a student diver signs the Medical Self-Declaration Form stating that all is OK, but is hiding a past illness?

The Form is a legal declaration. If a diver is found to have been untruthful and an accident occurs then that diver will be uninsured and may be held individually liable for the consequences.

What if I have had DCI but been cleared to dive? OR What if I have a condition listed on the Medical Self-Declaration Form but have been cleared to dive by a Medical Doctor?

The Medical Doctor will have issued you with a Certificate of Fitness to Dive. This certificate may cover a certain time period or be a clearance that self-declaration can be completed by the diver for the future. Provided the Medical Doctor has given you the all clear, then there should not be a
problem.

What about medical conditions such as high blood pressure, mental problems or substance abuse that may be missed by using Self-Declarations?

There have been instances of hypertensive divers developing acute pulmonary oedema (fluid on the lungs) from left ventricular failure when diving in cold water. This was mostly in the days of the neoprene wet suit. Now that dry suits are more common, this is no longer such a problem. In any case, the current medical system does not prevent the occasional diver developing pulmonary oedema.

Mental problems significant in a diving context would normally be detected during training.

Substance abuse is a fact of life these days and a medical examination would not normally detect it. Do not forget that by far the commonest drug to be abused is alcohol and the night in the pub before diving is often a silent contributing factor to diving accidents the following day.

Shouldn’t anyone partaking in a physical sport be health conscious as a matter of course?

As with all sports, the participants should be generally fit to partake in that sport. Health is an individual’s responsibility but any questions of concern that relate to health and diving can be directed to a suitably qualified Medical Doctor.

Are there any recompression chambers in Egypt which can treat DCI following the use of mixed gases?

Yes! There are chambers located in Marsa Alam, Safaga, Hurghada, El Gouna, Sharm El Sheikh and Dahab who are able to treat all types of diving accidents. Please remember to check your diving insurance before you travel. Some dive centres are able to offer insurance in resort so make enquiries to make sure you are covered.

What are the guidelines for flying after diving?

  • For a single no-decompression dive, a minimum preflight surface interval of 12 hours is suggested.
  • For multiple dives per day or multiple days of diving, a minimum preflight surface interval of 18 hours is suggested.
  • For dives requiring decompression stops, there is little evidence on which to base a recommendation and a preflight surface interval substantially longer than 18 hours appears prudent.

The recommended preflight surface intervals do not guarantee avoidance of DCS. Longer surface intervals will reduce DCS risk further.

I have just finished training a holidaymaker in Egypt. Should they receive their certification from Egypt or from their home country?

They should receive their certification from IANTD Egypt if the training was completed in Egypt.

I am an Instructor in Egypt currently training a sport diver who does not have time to complete their training with me. They will finish their course in their home country. Should the certification card come from IANTD Egypt?

No! If they complete their training in another Region, then the certification card should come from the Region in which the training was completed. 

I am an Instructor from Europe and am bringing a private group for training in Egypt. What should I do about registering the training and certifying the students?

You will need to notify IANTD Egypt and give details of what you will be doing. Please also check the IANTD Standards page 14 for the Cross Border Policy. If you complete the training in Egypt the certifications will be processed in Egypt.