Vintage Double Hose

Says so in black and white!

WORD!

In addition, the double hose breaths "dryer" than some single hose. The internal mechanism is protected from grit and salt. This may allow the dbl hose to function much longer between service procedures. The dbl hose is not sensitive to freezing conditions and will not lock up or free flow. The hose loop keeps the mouthpiece away from sand during beach/surf entry. Subjectively, the dbl hose breaths quieter, eg bubbles don't roar close by the ears. The mouthpiece is less likely to get "lost". The dbl hose mouthpiece will not get ensnared in straps during self donning. One big advantage of the dbl hose by comparison, a light mouthpiece, has diminished over time as single hose went to plastic. On the other hand, there have been problems with plastic second stages (single hose). For one thing, plastic 2nds sometimes crack; secondly, the plastic parts are more sensitive to icing and can be accidentally destroyed by use of some common solvents. As mentioned in the old article above, the large second stage diaphragm of the dbl hose produces more cracking force on the poppet eliminating the need for complex compensatory devices like "air balance" valves which are designed to increase spring force only when the system is pressurized. Thus, the 2nd stage of the dbl hose can use a firm poppet seat and strong spring which increases the stability and effective lifespan. In addition to the balance valve, some single hose employ adjustable spring tension or spring tension reducers for storage periods, a mechanical device used to prevent seat "engraving". This particular issue is of not problematic to dbl hose systems that I am aware of. Thus, the relative simplicity of the dbl hose pneumatics should reduce the need for maintenance. This has been my experience. The hoses of the dbl hose are sensitive to sunlight and need to be inspected for checking and rot. However, any damage is apparent and not likely to lead to catastrophic failure which sometimes occurs with the single hose. Single hose users may bring this upon themselves since removal and replacement of a booted single hose is sometimes difficult and may discourage inspection.

The few sets of silicone hoses that are out in use are not sensitive to sunlight and I don't think that EDPM rubber is all that sensitive. Neoprene holds up decently as well. I never really thought of the hoses as being a detrimental consideration--other than cleaning them.

James

"Double hoses are superior"... you're preaching to the choir on that one Bryan..