Diver Daves' Mark-15 DSV Page 2

The Dive-Surface Valve (DSV) is really the divers 'window to the loop'. The original Mark-15 used the old Scott DSV, which is a fairly inefficient design. This shows the original DSV, with the brass flip-lever for opening and closing it on the lower left. Most all of these have been retired from service, in favor or large diameter hoses and big-bore DSV's.

This is an example of a more modern large-bore DSV. This one was manufactured by Halcyon, and originally incorporated an open-circuit regulator mounted on the bottom as well. This type of design is used with larger diameter hoses, and provides better work of breathing than the old Scott DSV. Similar DSV's are available from Divematics, and from a small number of other suppliers.

Yet another DSV is this custom example made for me by Tracy Robinette at Divematics. It incorporates a Poseidon Cyklon second stage mounted on the bottom, with the DSV constructed so that selection of 'loop off' results in an instant selection of 'open circuit on'. This system is an essential part of closed circuit diving when using a full face mask, and some like to use it at all times. I prefer a more simple design for use with a normal mask, however this design allows removal of the regulator and substitution of a blanking plate for use without the regulator attached.

Connection large-bore hoses to the Mark-15 center section has been the subject of several different solutions. One solution has been to machine an adapter piece to allow conversion of the sizes and threads. Here a brass adapter is shown that allows the use of Draeger Atlantis hoses on the Mark-15. Similar adapters have been made for other hose styles.

This is the complete hose-set with the Divematics DSV, Poseidon second stage, Draeger hoses and couplings, and the custom machined adapters. You can see that obtaining the 'best' may need to include combining the products of several different manufacturers, along with some custom work to bring it all together. This is why rebreather use is still a work in process, with many different people working to build and assemble the best possible system from the components that are available.

	The Dive-Surface Valve (DSV) is really the divers 'window to the loop'. The original Mark-15 used the old Scott DSV, which is a fairly inefficient design. This shows the original DSV, with the brass flip-lever for opening and closing it on the lower left. Most all of these have been retired from service, in favor or large diameter hoses and big-bore DSV's.
	This is an example of a more modern large-bore DSV. This one was manufactured by Halcyon, and originally incorporated an open-circuit regulator mounted on the bottom as well. This type of design is used with larger diameter hoses, and provides better work of breathing than the old Scott DSV. Similar DSV's are available from Divematics, and from a small number of other suppliers.
	Yet another DSV is this custom example made for me by Tracy Robinette at Divematics. It incorporates a Poseidon Cyklon second stage mounted on the bottom, with the DSV constructed so that selection of 'loop off' results in an instant selection of 'open circuit on'. This system is an essential part of closed circuit diving when using a full face mask, and some like to use it at all times. I prefer a more simple design for use with a normal mask, however this design allows removal of the regulator and substitution of a blanking plate for use without the regulator attached.
	Connection large-bore hoses to the Mark-15 center section has been the subject of several different solutions. One solution has been to machine an adapter piece to allow conversion of the sizes and threads. Here a brass adapter is shown that allows the use of Draeger Atlantis hoses on the Mark-15. Similar adapters have been made for other hose styles.
	This is the complete hose-set with the Divematics DSV, Poseidon second stage, Draeger hoses and couplings, and the custom machined adapters. You can see that obtaining the 'best' may need to include combining the products of several different manufacturers, along with some custom work to bring it all together. This is why rebreather use is still a work in process, with many different people working to build and assemble the best possible system from the components that are available.