AP Diving AP50 - 5 Shortening Auto Air Medium Pressure (MP) Hoses; Important Notice: Beware: TWO Types of Hoses and Connectors

AP Diving Ltd. Medium Pressure and Convoluted Hose Shortening Instructions
Page 24 of 38
5. Shortening Auto Air Medium Pressure (MP) hoses
5.1 Important notice: beware: TWO types of hoses and connectors!
It is very important to know that over time AP has used two types of hoses for the Auto Air.
The Auto Air is (also) a 2
nd
stage regulator, and as such fitted with a special connector and
associated hose end that guarantees that the gas flow is high enough throughout its
operating depth (according to EN250:2014). A normal MP snap connector, as used for BCD,
wing, counterlung or drysuit inflators does not generally deliver sufficient flow.
- AP used a larger bore hose (AP150C) for the Auto Air, fitted to:
o All AP Evolution rebreathers until 2005,
o All AP Inspiration rebreathers until 2008, and
o All AP BCD’s and wings fitted with an Auto Air until February 2009.
- After these dates the hose fittings were modified and the larger bore hose was replaced
with the standard MP hose (AP50C), while still satisfying the requirements of the EN250
standard.
The net result is that “in the field” you may encounter TWO types of Auto Air hoses and
subsequently different hose ends and snap connectors.
The hoses are different in outside diameter as well as bore:
- The older type Auto Air hose (AP150C) has a bore of around 7.9 mm (5/16”) and an
outside diameter of around 14 mm. It was used ONLY for the Auto Air.
- The new, standard type of MP hose (AP50C) has a bore of around 6.35 mm (1/4”)
and an outside diameter of around 13 mm. It is now used for both Auto Air and
inflators, fitted to rebreathers as well as BCD’s and wings.
These two types of hoses and their end connectors MAY NEVER be mixed:
- Using a large 14 mm diameter / 7.9 mm (5/16”) bore hose with a normal diameter hose-
end or snap connector will seriously damage the hose (as in: causing deep cuts into the
outside of the hose) and as such will very likely result in a severely weakened hose that
will burst sooner or later close to the fitting.
- Using a normal 13 mm diameter / 6.35 mm (1/4”) bore hose with a large diameter hose-
end or snap connector will create a hose that is too loose hooked into the hose-end, and
as such is very likely to spontaneously come off, causing what effectively is a burst hose.
So always make sure you use the correct type hose end connector and diameter hose:
- The new AP50C MP hose goes with the new type smaller diameter connector, OR
- The older, larger diameter AP150C MP hose goes with the older type larger diameter
connector.
TOP:
AP50C 13 mm diameter /
6.35 mm (1/4”) bore hose with
tapered snap connector
BOTTOM:
Larger diameter AP150C 14
mm diameter / 7.9 mm (5/16”)
bore hose with straight snap
connector