JFD Divex SLS Mk IV User manual

Operation and Maintenance Manual
for the
Secondary Life Support (SLS Mk IV)
System Backpack
Part Number: B44771
Document Number: P1939-OM-131
Revision: 11

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OM131 i
P1939-OM-131 R11 Approval Sheet
APPROVAL SHEET
Document Information
Manual No Advitium No Title Classification Current
Revision Date
OM131 P1939-OM-131 Secondary Life Support (SLS) System
Mk IV Backpack Operation and
Maintenance Manual
Commercial in
confidence 11 14/12/2015
Revision History
Rev Date BY CHK APP Comments
1 12/11/2001 PGB David Smith David Smith ECN: 3633
2 31/01/2002 PGB Ray Wylie Ray Wylie ECN: 3702
3 09/10/2003 Linda Leckie Jamie Massie Jamie Massie ECN: 4597
4 30/10/2006 Christine Bain Eliot Aitken Ray Wylie ECN: 8903
5 21/12/2009 Debbie Allan George McClure Calum Crawford ECN: 13136
6 08/01/2014 Debbie Allan Alastair Naylor Mark Stevens ECN: 16338
7 23/07/2014 Debbie Allan Vladimir Garzon Mark Summers ECN: 16825
8 09/09/2014 Debbie Allan Alastair Naylor Scott Waddell ECN: 16972
9 19/05/2015 Jurgina Lastakauskiene Fraser Young Alastair Naylor ECN: 17875
10 06/07/2015 Molly Gray Alastair Naylor Steven Coull ECN: 18241
11 14/12/2015 Jurgina Lastakauskiene Alastair Naylor Philip Black ECN: 18839
Original Approvals
Responsibility Name Position Date
Author John A. Rendall Engineer January 2001
Checked David Smith Senior Engineer January 2001
Approval David Smith Senior Engineer January 2001
Copyright Details
© 2015 JFD
Copyright of this document is the property of JFD and it may not be copied, used or otherwise disclosed in whole or in
part except with prior written permission from JFD or, if this document has been furnished under a contract with another
party, as expressly authorised under that contract.

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Approval Sheet P1939-OM-131 R11
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OM131 iii
P1939-OM-131 R11 Preface
PREFACE
The Secondary Life Support (SLS) System is an emergency breathing apparatus intended for use
by professional saturation divers, operating from a diving bell. The system is intended for use in the
event of a fundamental failure of a diver’s primary life support system (e.g. loss of primary breathing
gas, loss of hot water, etc). It has been designed in response to the acknowledged need to enhance
diver safety, as divers begin to work to extreme depths in the world's most hostile diving
environments. The System operates on a semi-closed circuit principle with complete independence
from the diver's primary breathing system.
The SLS System meets the Norwegian Petroleum Directorate (NPD) Regulations 1995, Section 38,
which requires that whilst breathing at a rate of 62.5 lpm (litres per minute) RMV (respiratory minute
volume), the diver should be provided with a minimum of 10 minutes of breathing gas in order to
return to the safety of the diving bell. It consists of a self-contained Backpack and Helmet that have
been the subject of considerable development and testing.
Feedback from users of the SLS System, since it was introduced in 1986, has resulted in several
design changes that have enhanced performance, diver comfort and safety. These changes brought
about the introduction of the SLS Mk II in 1988, the SLS Mk III in 1992 and the current and most
advanced version in 1996, the SLS Mk IV. The main areas of change in the Mk IV are:
a. Improved serviceability with redesigned backpack housing and scrubber housing.
b. Improved scrubber canister door sealing arrangement and strengthened door.
c. A refillable scrubber canister with a screw on cap that is easier to fill.
d. The incorporation of a positive pressure indicator (a Rotowink) that allows the diver to visually
confirm the correct operation of the positive pressure system.
e. Various improvements to the harness and actuation system.
This Manual contains information for the operation and maintenance of the SLS System Mk IV
Backpack. This consists of a main housing containing a gas injection system, a CO2scrubber
canister and a thermal regenerator. The backpack harness also contains the system counterlungs.
The operation and maintenance of the SLS System Mk IV Helmet is documented in a separate
Manual with the reference OM112.
It is essential that personnel both operating and maintaining the SLS System are completely familiar
with all the operational and maintenance procedures. Divers should have attended a Familiarisation
Course and be totally comfortable and competent in the operation of the equipment, while
technicians should have completed the Divex three (3) day SLS System Training Course.
It is also important that the level of diver to technician competence is maintained and achieved to a
high level through regular use or experience. If in doubt of the individuals competency the person
should be re-trained.

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Preface P1939-OM-131 R11
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OM131 v
P1939-OM-131 R11 List of Abbreviations
LIST OF ABBREVIATIONS
Abbreviation Definition
cm Centimetre
CO2Carbon Dioxide
ft Foot or feet
H2O Water
in Inch
JJoule
kg Kilogram
lb Pound (weight)
LH Left Hand
lpm Litres per minute
Lt Litre
mMetre
mbar Millibar
mm Millimetre
msw Metres seawater
Mk Mark
NNewton
NPD Norwegian Petroleum Directorate
NUTEC Norwegian Underwater Technology Centre
O2Oxygen
psi Pounds per square inch
RH Right Hand
RMV Respiratory Minute Volume
SI System International
SLS Secondary Life Support
US United States
WG Water Gauge
WOB Work of Breathing

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OM131 vii
P1939-OM-131 R11 Warnings
WARNINGS
1. Failure to maintain the SLS System Mk IV Backpack in accordance with this Manual (using
original SLS System spare parts) or use by a person or persons unfamiliar with its operation,
could result in a serious hazard or fatal injury to personnel.
2. This SLS System Mk IV Backpack contains a high-pressure helium / oxygen mixture for
breathing purposes. Only special purpose, oxygen compatible, lubricant (e.g. Christo-lube
fluorinated grease - Divex Part No. SM034) should be used on specified components that
come into contact with high pressure, oxygen rich mixtures.
3. Naked lights or smoking in the vicinity of the gas cylinders may cause an explosion.
4. The system must be depressurised before disconnecting any part of the gas system.
5. Due to the very high levels of energy stored within compressed gas, it is potentially very
dangerous. Care must therefore be taken when charging the gas cylinders and safety
goggles must be worn. Ear defenders should also be worn.
6. Care must be taken to ensure that the replacement intervals specified in this Manual are
adhered to for all components.
7. Care must be exercised in the storage of the SLS System Mk IV Backpack to ensure that it is
maintained in a clean state, ready for use. If it is to be stored at temperatures below 0oC, it is
essential that the equipment is dried thoroughly before storage.
8. Correct planning of any operation using the SLS System is essential.

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OM131 ix
P1939-OM-131 R11 Table of Contents
TABLE OF CONTENTS
Page
Chapter 1 - Introduction ................................................................................................................................... 1
Chapter 2 - Technical Description .................................................................................................................. 13
Chapter 3 - Operating Information ................................................................................................................. 31
Chapter 4 - Maintenance Instruction .............................................................................................................. 53
Chapter 5 - Parts Catalogue .......................................................................................................................... 91

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OM131 1
P1939-OM-131 R11 Chapter 1
CHAPTER 1 - INTRODUCTION
CONTENTS
Page
1.1 Purpose of equipment ..................................................................................................................... 2
1.2 General description ......................................................................................................................... 2
1.3 Performance and Limitations .......................................................................................................... 5
1.3.1 Work of breathing ........................................................................................................................... 5
1.3.2 Oxygen partial pressure / endurance .............................................................................................. 5
1.3.3 Carbon dioxide scrubbing / thermal performance ......................................................................... 11

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Chapter 1 P1939-OM-131 R11
1.1 PURPOSE OF EQUIPMENT
The Secondary Life Support (SLS) System is an emergency breathing apparatus designed for use
by professional saturation divers, operating from a diving bell. It is intended for use in the event of a
fundamental failure of a diver’s primary life support system (e.g. loss of primary breathing gas, loss
of hot water, etc). The System operates using semi-closed circuit breathing apparatus principles and
provides complete independence from the diver’s primary systems. The SLS System meets the
Norwegian Petroleum Directorate (NPD) Regulations 1995, Section 38, which requires that whilst
breathing at a rate of 62.5 lpm (litres per minute) RMV (respiratory minute volume), the diver should
be provided with a minimum of 10 minutes of breathing gas in order to return to the safety of the
diving bell.
1.2 GENERAL DESCRIPTION
The SLS System comprises a Backpack (Fig 1.1, Item 1) and a Helmet (Fig 1.1, Item 2). The
operational principle of the System is basically that of a conventional semi-closed circuit breathing
apparatus, in which exhaled gas is captured in the counterlungs and is then re-breathed by the
wearer, after removal of the carbon dioxide (CO2) and replacement of the oxygen.
The SLS System layout is shown in Fig 1.2 with the Helmet (See separate Manual Ref: OM112) in
plan view. The Backpack consists of a main housing containing a gas injection system, a CO2
scrubber canister and a thermal regenerator. The main harness also contains the system
counterlungs.
The gas injection system has three (3) heliox cylinders manifolded together with a charging point,
burst disc, two stage regulator, injection orifice, single stage regulator, demand regulator and a
overpressure indicator.
The CO2scrubber canister provides a chemical absorbent bed for the removal of the carbon
dioxide. A thermal regenerator temporarily stores the heat within the breathing gas in order to avoid
losing it to the water as the breathing gas passes into flexible bags (the counterlungs). The SLS
Backpack harness has the counterlungs fitted to its shoulder straps.
The mixture of breathing gas required depends on diving depth, and complete details are given in
the operating information within the 'Preparation for Use' procedures (section 3.1.1).
During normal diving operations the SLS System is worn in stand-by mode with the mouthpiece
retracted into the helmet interface assembly. The counterlungs are mounted on each of the diver’s
shoulders and are stored packed in strong fabric enclosures to protect them from damage.
Two actions are required to activate the SLS System:
1. The interface valve on the right hand side of the Helmet has to be rotated through 180o, to
push the mouthpiece into the oral / nasal where the diver can bite onto it.
2. An actuation handle on the harness has to be pulled to deploy the counterlungs and pull a
spool valve which switches on the gas bleed for make-up gas.
NOTE
If the actuation handle is not pulled the diver will run out of breathing gas as the system has now
become open circuit.

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P1939-OM-131 R11 Chapter 1
Fig 1.1 SLS System Mk IV

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Chapter 1 P1939-OM-131 R11
Fig 1.2 SLS system layout

OM131 5
P1939-OM-131 R11 Chapter 1
1.3 PERFORMANCE AND LIMITATIONS
The SLS System has been proven in extensive unmanned and manned testing. A selection of
unmanned test data is presented below.
1.3.1 Work of breathing
Fig 1.3 shows the work of breathing in Joules per Litre as a function of breathing rate in lpm RMV at
a depth of 400 msw using heliox gas. The W.O.B. performance is even better at shallower depths.
The dashed line indicates the maximum W.O.B. permitted within the HSE/NPD Guidelines at >180
msw, the dotted line showing W.O.B. maximum <180 msw.
Fig 1.3 Work of breathing
1.3.2 Oxygen partial pressure / endurance
The duration of the bailout which the SLS System provides depends on one of two factors; the time
taken to fully deplete its stored gas or the life of the CO2scrubber canister. The oxygen partial
pressure within the System will vary depending on diver breathing rate. This is illustrated in Fig 1.4
to Fig 1.12 for depths from 50 msw to 500 msw. The System’s cylinder duration can also be seen
from these graphs but it should be noted that at shallow depths duration is limited by the life of the
CO2scrubber canister.
With the diver at rest, the oxygen partial pressure rises from its initial value (corresponding to the
umbilical gas) towards 2 bar (pp) At increasing workloads, the oxygen partial pressure is lower, but
at no time falls below 0.2 bar. The System injects gas until such time as the cylinders become
depleted. Following this, the diver will progressively breathe down the oxygen content in the
System. However, it should be noted that the gas remains breathable for some considerable time
beyond exhaustion of the stored gas.

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Chapter 1 P1939-OM-131 R11
Fig 1.4 Partial pressure of oxygen at 50 msw
Fig 1.5 Partial pressure of oxygen at 100 msw

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P1939-OM-131 R11 Chapter 1
Fig 1.6 Partial pressure of oxygen at 150 msw
Fig 1.7 Partial pressure of oxygen at 200 msw

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Fig 1.8 Partial pressure of oxygen 250 msw
Fig 1.9 Partial pressure of oxygen at 300 msw