In 1997, after many years of intensive R&D, Ambient Pressure Diving (APD) launched the world’s first production closed circuit rebreather – the award-winning and best-selling INSPIRATION CCR.

With 3 litre cylinders, easy maintenance and simple preparation - the Inspiration brought the benefits of optimal gas consumption and gas mix at all depths to the forefront of diving.

Quickly becoming the choice of expedition divers, film makers and sports divers alike, ranging from beach diving to RIB diving. right up to 100m expedition dives.

The Inspiration was the first...

...to achieve CE certification; the first (and only) CCR to feature dual independent oxygen controllers (Patented), the CCR to set the standard in PO2 control accuracy and scrubber duration; the first to achieve minimal breathing resistance in all diver positions and attitudes, the first mass produced and affordable CCR on the market.

The first to achieve worldwide distributorship with all that entails, including the development of the first unit-specific training courses by the major training agencies; and not least, the innumerable individual firsts that have been achieved by the many thousands of INSPIRATION CCR divers in the world today - from the discovery of virgin wrecks to personal depth and exploration records.

Vision or Classic?

The Inspiration is now available as the Inspiration Vision - with all the innovations and options detailed on this site and the Inspiration Classic - with the original electronics and twin handsets:

Go to Vision Electronics >>

Go to Inspiration Classic >>

View the APD Rebreather Comparison table for features and specs (opens in new window) >>

Retro-fit Vision

Existing Inspiration units can be retro-fitted with the Vision package.

This upgrade consists of the Vision electronics head on a new Inspiration-size 2.5kg scrubber unit, the Head Up Displays, wristset display and all the options including integrated decompression and CO2 scrubber monitor.

For further details on retro-fitting existing Inspiration, please contact Ambient Pressure Diving >>

WHAT IS A CCR????

Closed Circuit Rebreathers

In contrast to conventional scuba or open circuit where most of the breathing gas is wasted on exhalation into the surrounding water, APD rebreathers are all fully closed circuit systems in which all of the exhaled breath is retained within a closed loop.

It is then filtered and refreshed and recycled back to the diver for further use, giving the ultimate endurance of any breathing apparatus.

Only during ascent and mask clearing are bubbles emitted.

A. Exhaled breath leaves the diver’s lungs and is directed into a one-way loop or closed circuit starting at the unit’s exhale counterlung.

B. It then travels, via a water-trap, over the right shoulder into the scrubber unit where it passes upwards through a chemical (Sofnolime) filter stack. This effectively scrubs the breathing gas of carbon dioxide.

C. Inside the mixing chamber, three independent oxygen sensors measure the oxygen pressure, the PO2, of the mix. If the PO2 drops (due to the diver’s metabolism or due to ascending) below a predetermined target level called the PO2 setpoint the oxygen controller opens an oxygen valve or solenoid bringing the PO2 back up to the setpoint – a very simple system.

D. Scrubbed and refreshed the breathing gas returns via another water-trap to the inhale counterlung ready for use in the next cycle.

Diluent Gas

There are two onboard cylinders (3 litres on the Inspiration, 2 litres on the Evolution). One contains pure Oxygen, the other a diluent Gas - usually Air.

The diluent has several functions:

• Automatically injected into the inhale counterlung by the ADV (Auto Diluent addition Valve) on descent in order to maintain counterlung volume (or manually injected by the diver if no ADV is fitted). It is also used for BCD and dry-suit inflation. Only small quantities are used – typically 30-40 bar per dive.

• As a ‘diluent’ or dilutant it dilutes the gas mix so that it is safe to breathe at depths greater than 6m.

• The third and extremely important function is that it provides a reserve gas supply for either a ‘diluent flush’ or open circuit bailout if needed. (See Safety & Bailout)

Oxygen Control

Both the Inspiration and Evolution with Vision electronics utilise the same oxygen control program as the Classic Inspiration – an oxygen controller which was developed specifically for APD and has set new standards for Sport and Military rebreathers in terms of holding and maintaining the PO2 close to the target pressure (setpoint) in all phases of the dive.

It features a variable inject time depending on the variance of the O2 level from the chosen setpoint: the further from the setpoint, the longer the oxygen valve opens. So even during fast ascents or periods of high workload, the controller is easily able to maintain the setpoint without manual intervention by the diver. The APD oxygen controller is unique among closed circuit systems in that it holds the O2 pressure at the mouthpiece within an extremely tight tolerance band – typically ± 0.02 bar.

Dual Control

Although the new Vision hardware is quite different to the Classic Inspiration (in brief: a wristset Primary Display and Head up displays – showing both controllers – replace the separate Master & Slave handsets, an intelligent battery system, built-in deco computation and a host of other new features) in essence, both systems feature two independent control systems: one Master (primary control) and one Slave (back-up control) each with it’s own power supply.

APD CCRs are the ONLY rebreathers with two independent oxygen controllers (patented). The Slave controller, with its own power supply, not only monitors the Master controller but it also monitors the PO2 independently, giving warnings when appropriate (independently) and opens the solenoid (independently) if the PO2 drops to 80% of setpoint. In the event of the Master shutting down, the Slave will instantly take over and control the PO2 in the loop.

Real Time PO2 Display

The display shows all three PO2 sensor readings in real-time – not hugely averaged out to show a “rock steady” display - as do other makes of rebreather. We give you the facts as they happen. This allows you to compare response rates as well as sensor values and validate or sanity-check the displayed readings before and during the dive against known values.

Warnings designed to grab your attention

By sounding the audible alarm in combination with a flashing light in the head up display, the Vision really attracts your attention when it needs to. Warnings are given for Low Oxygen at 0.4 bar, High Oxygen at 1.6 bar, PO2 deviation set at 0.2 bar below setpoint, Battery, Oxygen sensor, Scrubber, as well as CNS and OTU warnings.

A Simple HUD System

SOLID GREEN for GO, anything else - “Check the Handset”. In the unlikely event that the handset has failed the HUDs are still independently providing information about the unit and will tell you enough about battery, cell and PO2 status to enable the closed circuit dive to be aborted on CCR. In total there are THREE independent monitoring systems and displays available to the diver! The Vision electronics also feature many other suppressible and non-suppressible warnings and fail-safe systems.

In total there are THREE independent monitoring systems and displays available to the diver! The Vision electronics also feature many other suppressible and non-suppressible warnings and fail-safe systems.

To sum up: all APD ccrs have multiple systems providing warnings that give you adequate time to assess a problem and take appropriate action.

Redundancy Built In

Three oxygen sensors, two oxygen controllers, two batteries with cross feed capability, two Head up displays built into one neat unit combined with the multi-function wristset ensure back up.

Combine this the two methods of adding oxygen to the breathing circuit and the two methods of adding diluent to the breathing circuit, both allowing for external feed of any number of external cylinders makes the APD CCRS incredibly versatile.

Constant Partial Pressure of Oxygen (PO2)

The APD controller maintains a constant PO2 at the chosen setpoint throughout the dive. This gives the advantages of oxygen-rich diving at every stage of the dive down to 50m.

How does this work?

On open circuit scuba the gas mix is constant (approx. 21% O2 in air) at all depths while the PO2 is variable – i.e. 0.21 bar at the surface, 0.42 at 10m, 0.63 at 20m and so on.

With APD CCRs it is the opposite case: the PO2 is constant and the mix or fraction (FO2) is variable. The PO2 is held at the chosen setpoint by the controller injecting oxygen into the breathing loop. The result is that the FO2 varies with depth.

This can be better understood if you imagine a diver ascending from 50m...

At 50m the ambient pressure is 6 bar. The Inspiration controller maintains the PO2 at the chosen default setpoint of 1.3 bar* - so, the fraction of oxygen in the loop is 1.3 ÷ 6 = approx. 0.21 or 21%. As the diver ascends the ambient pressure drops so oxygen is injected by the controller in order to maintain the PO2 at 1.3 bar. So, as the diver ascends the percentage of oxygen in the mix rises. For example: at 30m (4 bar) you would breathe 1.3 ÷ 4 = 32%, at 16m : 50%, at 6m : 81% and at 4m : 93% O2.

*APD CCRs have 2 default setpoints: 0.7 bar used at the surface and the descent and 1.3 bar for the dive. Both setpoints are user adjustable (underwater if necessary): the lower from 0.5 to 0.9 bar and the higher from 0.9 to 1.5 bar.

In other words...

APD closed circuit rebreathers deliver super-Nitrox – the optimum oxygen-rich mix at every depth throughout the dive and a super-O2-rich mix during decompression.

Trimix/Heliox

For Trimix dives it is necessary to pre-mix a diluent that is suitable for the target depth in terms of PO2 and PH2. Although, on these dives there is no increase in deco-free bottom times compared to open circuit, the fact that the breathing mixture is optimised during the ascent reduces dive planning, simplifies the logisitics, reduces the gas cost exponentially, can reduce the deco times and gives the diver the stress-reducing flexibility of extended gas durations.

ADVANTAGES

Dramatically Increased No-Stop Times

The significance of diving with an oxygen-rich breathing gas is that the percentage of inert gas is considerably lower. Consequently, the time allowed to dive before decompression is required – no-stop time – is dramatically increased.

Down to 30m these benefits are huge. For example you could stay for nearly 3 hours at 20m (with the Inspiration, or about 2.5 hours with the Evolution - due to the smaller scrubber unit) without requiring deco compared to just 36 minutes on open circuit.

Below 30m APD CCRs significantly extend no-stop times – typically twice the dive times at air-range depths currently dived on open circuit.

Greatly Reduced Deco

If you do stay down long enough to incur deco penalties, these obligations are greatly reduced. To give just one example:

A dive to 30m for an hour will incur only 11 minutes stop time compared to about 74 minutes deco on open circuit air.

Decreased Gas Consumption

One of the most significant advantages of fully closed circuit diving is the massive increase in gas efficiency.

Open circuit SCUBA is extremely wasteful of gas and this waste increases dramatically with depth. At 30m a typical open circuit diver breathes at the rate of 100 litres per minute: 98.9% of which is just volume make-up and is simply bubbled away – every minute!

In contrast, the APD CCR diver’s breathing volume normally only needs to be made up once and the metabolised oxygen replaced as the dive progresses (average metabolic consumption = about 1 litre/min) - reducing the gas demands to a fraction of open circuit levels. Greater gas endurance, smaller cylinders, less visits to the filling station and cheaper fills (particularly when using Trimix) are just some of the benefits of APD closed circuit rebreather diving.