Tourill MK 1.5 rebreather

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Passive addition rebreathers are used more and more. There have been several developments recently. The latest to add to the list is the Tourill MK 1.5. The rebreather is a nice German design that offers a large group of people access to this kind units. The very affordable unit has a very nice quality finish and is well worth to have a second look at. Christoph Hellwig managed to improve the original design and called is Tourill MK 1.5. The unit can be bought direct from: http://www.wassersport-hellwig.de/
I hope you enjoy the teardown. You can ask any question about the unit direct to Christoph here.

The Tourill MK 1.5 passive addition rebreather.

text by Christoph Hellwig
2004

The Tourill MK1.5 was born out of the “design study” called “Sphere” from Deep Access. Four friends and me bought such units in the beginning of 2004. After my third dive with the unit, I did a complete teardown of my unit, because the unit was heavy leaking. I found some major bugs in my unit…We got really a prototype of a “design study :-((

The other guys who bought such a unit had also problems with the units. I decided to built a unit which is more safe and dive able and more easy to configure. Two other guys where also very active to eliminate the bugs in their units. I put the best ideas together and built my new unit. After several diving, and testing hours and changes in the unit, the Tourill MK 1.5 was born.

So let’s do a teardown:

Here you see the unit complete with gas switch block and DSV in the frame. This is the new frame, which is very stable and electro polished for corrosion reasons:

Therebreathersite Tourill MK1.5 001
One of my frames with 40cu.ft. tanks used for shallow lake diving. Since I use this frame only in fresh water, it is not electro polished, only pickled.
Therebreathersite Tourill MK1.5 002
To bridge the tanks, I use the “standard” way. Two isolation manifolds with Swagelok pipe connectors.
Therebreathersite Tourill MK1.5 003
The unit without the frame.
Therebreathersite Tourill MK1.5 004

The gas switch block is shown here. The hoses between switch block and the unit are without o-ring sealing.  The 90° connectors are made in the same way and are also provided with the unit.  

Therebreathersite Tourill MK1.5 005
To drive the gas switch block I use standard QC6 connectors with adapters made by Swagelok. If you drill  the 9/16” UNF adapter to 9.5mm it fits perfect a standard low pressure hose.
Therebreathersite Tourill MK1.5 006
The DSV. The threat’s in the union nut’s are coded, to prevent the user to mount the DSV in the wrong direction
Therebreathersite Tourill MK1.5 007
Therebreathersite Tourill MK1.5 008
To open the unit, just turn the head 1,5-3 times and pull it. The exhaled gas flows between the scrubber canister and the body through the Dräger one way mushroom valves. By using this way of gas routing, the scrubber is better insulated when you are diving in cold water environments.
Therebreathersite Tourill MK1.5 010
Here you can see the rebreather head with the scrubber canister, the spring loaded lower sift and the centered thread rod. These thread rod is used to adjust and spring load the lower scrubber sift. You can fill the unit with much sorb as you need for the dives (1,5-3,3KG). Also the thread rod is use as the “close mechanism”.
Therebreathersite Tourill MK1.5 009
If you look into the unit, you can see both the gas addition valves, the valve lifters, the overflow pips and in the center the one way valve cover which is also used as the “close mechanism”. The pipes prevent the Water to get in the large bellow. It flows from the tapered area in the minor bellow where the water is dumped, during the divers next inhale phase.
Therebreathersite Tourill MK1.5 011
Here again, the spring loaded lower sift
Therebreathersite Tourill MK1.5 012
The dismantled lower sift. The upper sift is self-supporting. No force is assigned on the scrubber canister lid or the head (because it is only POM 🙂 )
Therebreathersite Tourill MK1.5 014
The water trap downside, you can see the custom fittings for the gas addition valves include the 90° connectors (without O-ring seal) for the gas switch block, the overflow pipes, the valve lifters and one of the both Dräger one way mushroom valves, also the lock against rotation for the “close mechanism”. The black sleeves on the valve lifters are for fixing the lifters and limiter for the levers from the gas addition valves
Therebreathersite Tourill MK1.5 013
To come up to the counter-lungs just screw off the bottom pipe. To dismantle the bellows, just screw them off via the union nut.
Therebreathersite Tourill MK1.5 015
The dismantled counter lungs. The counter lungs are made from polyurethane which is very flexible (easy to breathe) and food-safe. Ratio of the lungs is 1:10, other ratio is possible.
Therebreathersite Tourill MK1.5 016
Therebreathersite Tourill MK1.5 017

If you need more information about the unit or want to do a test dive please contact me by email info@wassersport-hellwig.de.
Training for this unit is available in Germany only till now, but I’m working to increase the training network and work together with a official training organization.

The unit WAS sold for 3000,- to 4000,- euro* depending on the configuration.
Check out Christoph’s website here: http://www.wassersport-hellwig.de/

Christoph, thank you for your contribution to my website!
(2022: UNFORTUNATELY THE WEBSITE IS NO LONGER ACTIVE)

JW

Therebreathersite was founded by Jan Willem Bech in 1999. After a diving career of many years, he decided to start technical diving in 1999. He immediately noticed that at that time there was almost no website that contained the history of closed breathing systems. The start for the website led to a huge collection that offered about 1,300 pages of information until 2019. In 2019, a fresh start was made with the website now freely available online for everyone. Therebreathersite is a source of information for divers, researchers, technicians and students. I hope you enjoy browsing the content!

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