AP Diving AP50 - 1 Introduction; Reason for These Instructions; About MP and HP Hoses; Servicing

AP Diving Ltd. Medium Pressure and Convoluted Hose Shortening Instructions
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1. Introduction
1.1 Reason for these instructions
When you have finished reading these instructions you will no doubt agree with us that
shortening AP hoses is indeed simple, BUT “the devil is in the details”:
- Get the details (and tools) right, and you end up with a shorter hose that functions
perfectly and is also safe;
- Get them wrong and you end up with a hose that might detach from its end fitting, or
burst due to it becoming weak through using an incompatible / faulty combination of
parts.
1.2 About “MP” and “HP” hoses
The abbreviation “MP” used in these instructions stands for “medium pressure”. ONLY MP
hoses and convoluted hoses can be shortened “in the field” (i.e. outside the factory).
High Pressure (HP) hoses CANNOT be shortened “in the field”. This is only possible in
the factory, as it requires crimping the end fittings, which requires specialised factory-based
equipment.
- “Medium pressure” is pressure typically in the working range of around 10 bar.
MP hoses are typically used for inflators and regulators (between 1
st
and 2
nd
stage).
The EN250:2014 norm (paragraph 5.8.4 and 5.8.6) specifies that the burst pressure of
medium pressure hose assemblies shall withstand four times the rated working pressure
or at least 100 bar, whichever is the higher, without leakage or burst.
- “High pressure” is pressure typically in the working range of 200 to 300 bar.
HP hoses are typically used for high pressure gauges or filling whips, used for
monitoring the remaining gas supply in diving cylinders or for filling diving cylinders.
The EN250:2014 norm (paragraph 5.8.3 and 5.8.5) specifies that high pressure hose
assemblies shall withstand a pressure of four times the rated working pressure without
leakage or burst.
1.3 Servicing
Before servicing AP medium pressure or convoluted hoses you must receive instruction and
certification in hose shortening and end fitting maintenance by AP Diving.
Without the correct training it is possible to shorten hoses or service end fittings in an unsafe
manner.
The Inspiration range of closed circuit rebreathers’ CE certification to EN14143 is unaffected
by properly shortened hoses, provided that the shorter hoses do not affect the operation (e.g.
reachability of key components like inflators) or gas throughput and breathing resistance of
the rebreather in any way.
The AP hoses meet the requirements of the Personal Protective Equipment Directive
89/686/EEC – CE certification when fitted to an AP Diving rebreather.
They also meet the requirements as specified in European norm EN250:2014.
WARNING: when servicing AP hoses it is VERY important that all parts that may suffer
wear and tear get replaced. It is also very important that the correct tools are used to avoid
damaging any part of the hoses in the disassembly and assembly process.