Siebe Gorman Mouthpiece & Hose arrangement

[kgehring]

I have been playing with a Siebe Gorman Mouthpiece & Hose arrangement and can't quite figure out why the hoses leave the mouth piece in a "Y" configuration. Maybe it is not that crazy in the water using it? I have one mouthpiece that you can adjust the angle and that makes sense. Maybe some of our Euro friends can offer some info.

[luis]

It is British... they also drive on the left side of the road.

[YankDownUnder]

The Siebe Gorman MkVI Merlin was originally the Heinke Merlin. If you look closely at the mouth piece, it will be marked, and it may be one or the other. Siebes have a gas flow arrow, but the Heinkes do not. Either is correct, as existing stocks were used during the change over. Siebe bought Heinke in about 1962.

The mouth piece was designed to trap a minimum of water and be easier to clear if removed from the mouth underwater. The inverted U shape eliminated loose water sloshing around and therefor 'wet' breathing. US Divers valve cages will work in the Heinke design, but the originals are shaped differently, with the valve being closer to the mouth on both sides, assuming they were installed correctly. The replacement valves for USD regs will also fit.

The early Heinke models, such as the Mk III, or MkIV had a third valve cage in the exhaust hose, near the horn. Duck bill valves were not needed on those models. Your Merlin was the last British regulator to use the double hose system. They were used by the Royal Navy for many years. They were heavy, rugged and breathed better than almost any competitor. The body is cast machined bronze, and chrome plated. Early models also had a black wrinkle paint. The face is high impact black rubber. Threads on he fittings including the screws are BSF and hard to replace. Earlier Heinke models had the logo cast into the face. The regulator has a venturi jet in the second stage which is what gives it the good breathing characteristics. Some models have a by-pass valve for blowing air hrough the system and was used for rapid clearing. Pressure gauges can be fitted, but many were used with inverted tanks, that were decanted, and a gauge was redundent.

The correct hose clamps are chromed brass, but USD plastic will also fit. Should you wish to replace the hoses, the earlier black seamless ones sold by Dan look the same. You should insure that the hose clamps position the mouth piece comfortably, as position is important ith the Merlin design.

Should you wish to service the regulator I can provide a copy of the manual.

Other British double hose include: Submarine Products Sea Lion, Sea Lion II, Super Sealion, Atlantis, and Black Prince. There was a Heinke 'horn', the MkI,& MkII, MkIII, MkIV, Merlin V and Merlin VI. Merlins can be either Siebe or Heinke of course. The British do not use the term double hose regulator. They call these 'twin hose demand valves'.

I hope that helps.