Transcript Surface Supplied Diving

Surface-Supplied Diving
Sources
• Joiner, J.T. (ed ). 2001. NOAA Diving
Manual - Diving for Science and
Technology, Fourth Edition. Best
Publishing Company, Flagstaff, AZ.
• US Department of the Navy. 1999. US
Navy Diving Manual. Revision 4.
NAVSEA 0910-LP-708-8000. Naval/Sea
Systems Command, 2531 Jefferson Davis
Hwy, Arlington, VA.
Objectives
• After completing this training module you will
be able to:
– List four advantages and four disadvantages of
surface-supplied diving compared with scuba
– List seven considerations for pre-dive planning of
surface-supplied dives
– Give three examples of appropriate warning displays
for surface-supplied diving activities in high marine
traffic areas
Objectives
• After completing this training module you will
be able to:
– List at least two methods for supplying gas to a
surface-supplied diver
– Discuss the features of a surface-supplied diver’s
harness and the importance of a snap shackle
– Provide the important features associated with a
bailout bottle
Objectives
• After completing this training module you will
be able to:
– Describe and list two functions of a manifold block
– List the personnel requirements to deploy a surfacesupplied diver, and describe the basic responsibilities
of each assignment
– Explain the importance of checklists
Objectives
• After completing this training module you will
be able to:
– Explain basic line pull signals from tender to diver
and diver to tender
– Describe why knowing how to properly ventilate a
free-flow and demand style helmet or mask is
important to a surface-supplied diver
– List five surface-supplied diver emergencies and
describe actions to be taken
Objectives
• After completing this training module you will
be able to:
– Describe procedures used during the ascent and postdive phase of a surface-supplied dive
– List at least four considerations or procedures for
umbilical diving from a small boat
– State at least two basic supply pressure requirements
for both Free Flow and Demand style surfacesupplied systems
General
• One of the diving modes of choice for
underwater work that requires the diver
to remain submerged for extended periods
of time is surface-supplied diving
• This module describes some of the
techniques and procedures for divers
engaged in basic surface-supplied diving
History
• Prior to the
development of surfacesupplied diving,
underwater work was
performed by breath
holding and/or work
from diving bells
History
• A critical piece of the
groundwork for effective
surface-supplied diving was
laid in the late 18th century
with the development of
pumps capable of delivering
air under pressure
History
• Augustus Siebe is credited with the first
major breakthrough in surface-supplied
diving in 1819 with the invention of a
waist-length jacket with a metal helmet
sealed to a collar and fed air from the
surface by force pump
History
• Siebe later modified his design
incorporating the design for a
smoke apparatus developed by
John and Charles Deane
producing a closed suit design
with attached helmet; the direct
ancestor of surface-supplied
diving systems used by the US
Navy until the early 1980s
History
• No major developments occurred in hardhat gear until the 20th century with the
advent of mixed gases
Advantages
• Advantages of surface-supplied diving
over scuba diving are that it:
– Provides a direct physical link to the diver
– Permits hard-wire communication between
the diver and the surface
– Provides an assured, continuous breathing
gas supply and thus, longer bottom time
– Provides depth control
Disadvantages
• The disadvantages of surface-supplied
diving compared with scuba diving are:
– The surface-supplied diver’s mobility and
operational range are restricted by the length
of the umbilical
– The drag weight of the umbilical
– The large amount of equipment required to
support surface-supplied diving
Planning the Dive
• The success of any dive
depends on pre-dive
planning considering
dive objectives, required
tasks, environmental
conditions, hazardous
activities at or near the
dive site, personnel,
equipment, and
availability of emergency
assistance
Planning the Dive
• For areas with high marine traffic, an appropriate
warning display shall be exhibited near the work
site in clear sight of all personnel in the near vicinity
• This may include, but not limited to, shapes, lights,
flags, or placards
• A rigid replica of the international code flag “A” not
less than one meter in height should be exhibited
during all diving operations
Planning the Dive
• The dive supervisor
should complete a
Pre-Dive
Environmental
Checklist for every
surface-supplied dive
before deciding on
personnel and
equipment needs
Planning the Dive
• Surface conditions have greater effect on
the tender and other support personnel
than the diver
• Accurate depth measurements are
necessary for dive planning, as well as
information concerning bottom type, tides
and currents, marine life, gas
requirements, and underwater
obstructions
Minimum Equipment for
Surface-Supplied Diving
• Compressor, air
banks, or a
combination
• Diving Control
System
• A Mask or Helmet
• Umbilical
• Harness
• Stainless Steel Snap
Shackle
• Bailout Bottle
• Manifold Block with
Non-return Valve
• Exposure Suit (as
needed)
• Weight (as needed)
• Fins or Boots
• Dive Knife
Gas Supply
• A low pressure compressor designed for
surface-supplied diving can be used to supply
gas to the diver(s)
• These compressors must be properly filtered and
use special oil designed for breathing air
compressors, and must have a volume tank
• A bank of cylinders or a combination of bank
and compressor can also be used to supply gas
to the diver(s)
Schematic of a Low-Pressure CompressorEquipped Gas Supply System
Schematic of a Typical High-Pressure
Cylinder Bank Gas Supply System
Dive Control System
• A Dive Control System
connects the gas supply to
the umbilical
• It provides information on
the diver’s depth through
the pneumofathometer
hose; controls the flow of
gas to the diver(s); and can
include two-way hard wire
communication
• These systems range is size
from portable to built in
and range from simple to
complex, depending on the
application
Key Features of Diving Helmets
Lightweight Surface-Supplied
Masks
Band Mask
AGA Mask
EXO 26 Mask
Umbilical Components
• The diver’s gas
supply hose
needs to have a
smooth inner
bore of at least
3/8 in (9 525 mm)
inner diameter
• The umbilical can be assembled bundled or twisted with
the strength member separate or combined with the
communication hose
Snap Shackle and Harness
• The harness is usually made
of flat nylon webbing and is
outfitted with stainless steel
D-rings that can be used as
attachment points
• A quick release snap shackle
attaches the umbilical to the
diver’s harness
• This reduces the stress placed
on the attachment points of
hose to diver
• The shackle is designed to
remain closed under stress,
but can be released under
tension if necessary
Bailout Bottle
• The Bailout Bottle is an emergency air
supply in case there is a total failure of the
surface-supply system
• Or if the divers hose is severed
• Or in the event that the umbilical becomes
hopelessly entangled and cannot be freed
Bailout Bottle
• The Bailout Bottle must be of sufficient volume
to act as an emergency gas source and may vary
in volume capacity depending on the diving
depth and working conditions
• The Bailout Bottle is equipped with a separate
first stage
– When attached to a Bailout Bottle, this first stage
should be equipped with an over pressure relief valve
– This valve is necessary in case the first stage develops
IP “creep” that could cause the pressure in the hose
from the bottle to the manifold block to increase to
the point of bursting
Manifold Block
• The umbilical is threaded
on to the one-way, nonreturn valve of a
manifold block
• The manifold block is
attached to the divers
harness for use with
lightweight masks like an
AGA or EXO 26, but is
part of the helmet
assembly of the Superlite
or Band Mask
Manifold Block
• The diver’s mask and bailout bottle are attached
to the manifold block
• The knob on the manifold block opens and
closes a valve
• When closed, the valve isolates the bailout
bottle and keeps it from being breathed down
during the dive
Selecting the Dive Team
• The number of personnel necessary to
conduct surface-supplied operations
depends on:
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The equipment being used
The environmental conditions
Dive depth and platform type
How the diver(s) will be deployed and
retrieved, and the number of divers being
deployed
Selecting the Dive Team
• Deployment of one surface-supplied diver
could require as many as six people,
depending on the conditions and the
complexity of the dive:
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Working diver
Dive tender
Dive supervisor
Standby diver
Standby tender
Timekeeper
Selecting the Dive Team
• For less complex dives the number needed
to deploy a single diver could be reduced
to three people with individuals
performing multiple tasks:
– Working diver
– Supervisor/Timekeeper/Standby tender
– Tender/Standby diver
Selecting the Dive Team
• The diving supervisor is responsible for
planning, organizing, and managing all of the
dive operations; to include determining
equipment requirements, inspecting equipment
pre and post-dive, selecting team members and
assigning tasks, conducting briefings and
debriefings, monitors the progress of the dive,
coordinates emergency response, checks dive
logs and prepares reports on the dive
• The diving supervisor must remain at the dive
location at all times
Selecting the Dive Team
• The diver(s) must be qualified and trained in the
equipment and techniques of the dive, including
both line pull and voice signals
• The diver must keep surface personnel informed
of the progress of the dive, bottom conditions,
and real or potential problems
• Every diver is responsible for ensuring that their
dive gear is complete, in good repair, and ready
for use
Selecting the Dive Team
• The standby diver must be as well-trained
and qualified as the diver being supported
• A stand by is required for all surfacesupplied operations, regardless of size
• It is the responsibility of the standby diver
to be ready to provide emergency or
backup support whenever the diver is in
the water
Selecting the Dive Team
• The tender is either a qualified surfacesupplied diver or has received specialized
training required to be a competent tender
• Every surface-supplied diver must have at
least one tender in control of the umbilical
at all times
Selecting the Dive Team
• The tender:
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Checks the diver’s equipment
Checks the gas supply
Helps the diver get dressed
Helps the diver to/from the entry/exit point
Tends the diver’s umbilical to ensure no
excess slack or tension is on the line
– Maintains communication with the diver and
keeps the diving supervisor informed of the
diver’s progress
Selecting the Dive Team
• Long or complex dives may require a
standby tender to assist or replace the
primary tender
• This individual must also be fully
qualified and should attend all briefings
and be kept aware of what is going on
with the dive
Selecting the Dive Team
• The time keeper’s responsibilities include
keeping an accurate record of dive times,
depths, and noting all of the important
details of the dive
• During dives involving limited number of
dive team members, the tender or dive
supervisor may act as time keeper
Preparing for the Dive
• In addition to preparing equipment, diver,
and personnel for the dive; a pre-dive
checklist should be employed to ensure
the diver is properly dressed prior to
deployment and to identify and correct
potential problems
The Importance of Checklists
• It is common practice to use checklists
throughout surface-supplied diving
operations (pre, during, and post-dive) to
standardize procedures and minimize
errors
The Importance of Checklists
• These will be gone over in detail during
the hands on portion of your surfacesupplied diver training, and may vary
from the examples presented here
Preparing for the Dive
• A minimal pre-dive checklist consists of:
– Check to ensure the suit is donned properly
– Check diver’s safety harness and emergency bailout
system for fit and accessibility
– Check diver’s weighting
– Check and log emergency bailout system mixture and
cylinder pressure
– Check primary and secondary gas bank and supply
pressure
– Ensure gas flow to mask or helmet
– Check function of emergency gas system
– Check proper function of helmet or mask components
– Perform communications check
Preparing for the Dive
• Once deployed, the diver should stop just
under the surface and:
– Adjust the demand regulator air supply and
perform a “bubble check” for major leaks
– Recheck the function of the emergency supply
valve and free flow valve (the valve isolating
the bailout cylinder must be closed until
needed to avoid breathing the bailout gas
supply down during the dive)
– Repeat communications check
Tendering the Surface-Supplied
Diver
• Contact between the
tender and the diver
must be maintained
throughout the dive
• This contact starts with
the tender placing a hand
on the fully dressed diver
as the diver moves to the
entry point
• The tender maintains
physical control of the
diver as the diver enters
or leaves the water
Tendering the Surface-Supplied
Diver
• As the diver descends, the tender pays out slack
according to the decent rate, but never faster
than is needed by the diver
• The tender should always be able to feel the
diver
• Once on the bottom the tender and the diver
work as a team
• The tender should only supply enough slack in
the umbilical so as not to hinder the diver’s
work (usually about 2-3 ft)
Tendering the Surface-Supplied
Diver
• If voice communication is lost the tender and
diver must be able to communicate using linepull signals
• All communications between the diver and the
tender should be passed on to the dive
supervisor
• If the diver fails to respond after several
communication attempts, the situation should be
treated as an emergency
Line Pull Signals
• A line pull signal is one pull or a series of
sharp, distinct pulls on the umbilical
which are strong enough to be felt by the
diver or tender
• All slack must be taken out of the line
before the signal is given
Line Pull Signals
• From the tender to the diver:
– 1 Pull – “Are you OK?” When diver is
descending, 1 pull means “Stop”
– 2 Pulls – “Going Down”
• On ascent, 2 pulls means “You have come up too
far; go down until we stop you ”
– 3 Pulls – “Stand by to come up”
– 4 Pulls – “Come up”
Line Pull Signals
• From the diver to the tender:
– 1 Pull – “I am OK”
• When descending, 1 pull means “Stop” or “I am
on the bottom”
– 2 Pulls – “Lower” or “Give me slack”
– 3 Pulls – “Take up my slack”
– 4 Pulls – “Haul me up”
Line Pull Signals
• Most line pull signals are repeated back by
the person receiving them to communicate
the signal has been received and
understood
• Additional line pull signals will be
covered during the hands on portion of
surface-supplied training
The Dive
• surface-supplied
divers enter the water
using a “stage”, by
jumping, or by
climbing ladders
• The diver(s) are
relying on the
tender(s) to maintain
sufficient slack on the
umbilical
The Dive
• The following actions should be taken, as
appropriate:
– The diver should check buoyancy (being weighted
neutrally or negatively is dependent on the dive’s
objectives)
– The supervisor should verify that the gas supply and
communications are functioning properly, and that
the diver’s equipment is functioning satisfactorily
– The tender checks for leaks in gas supply fittings or
suit and looks for air bubbles
– The supervisor should give the diver permission to
descend
The Dive
• Actions to be taken, continued:
– The diver should descend down a descent or “shot”
line, equalizing pressure as needed
– Upon reaching the bottom the diver informs the
tender of the diver’s status and ensures the umbilical
is not fouled around the descent line
– To aid in relocating the stage, the diver may choose to
employ a travel line to the work area or may pass the
umbilical through the bail of the stage or bell
– The diver should proceed to slowly to conserve
energy and it is advisable for the diver to carry one
turn of the umbilical in hand to allow for unexpected
pulls on the hose
The Dive
• Actions to be taken, continued:
– The diver should pass over, not under, wreckage and
obstructions
– If moving against current, it may be necessary to
crawl
– If the diver is required to enter wreckage, tunnels,
etc., a second diver must be one the bottom to tend
the umbilical at the entrance to the confined space
– The diver(s) should be notified a few minutes in
advance of termination of the dive so that tasks can
be completed and preparations made for ascent
Pneumofathometer
• An open ended pneumofathometer hose is
used to check the diver’s depth
• The Dive Control System operator briefly
opens a valve on the control panel causing
the gas at the diver’s end of the pneumo
hose to equalize pressure with the
surrounding water
– The diver’s depth is displayed on a gauge on
the control panel
Pneumofathometer
• The diver’s depth should be checked
periodically during the dive
• The valve controlling gas to the pneumo
hose need not be opened during ascent,
the gas in the hose bubbles out as the
diver ascends producing an accurate
depth reading on the control panel gauge
Ventilation
• If the diver experiences rapid breathing,
panting or shortness of breath, abnormal
perspiration, or an unusual sensation of
warmth, dizziness, blurred vision, or if the
helmet/mask viewport becomes foggy,
there is probably an excess of carbon
dioxide in the headgear
Ventilation
• To eliminate excess CO2 in a free-flow helmet or
mask the diver must ventilate the helmet or
mask by increasing the flow for a minimum of
15-20 seconds
• CO2 retention is not as common in demand
valve helmets and masks as long as the diver
breaths normally; has the flow valve adjusted
properly; or does not over work the system with
too high a work rate
• To ventilate a demand valve helmet or mask, the
free-flow or demand regulator purge valve can
be used for five to ten seconds
Diver Emergencies: Fouling
• A surface-supplied diver’s umbilical may become fouled
for any number of reasons
• Divers who are fouled should:
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Remain calm and control breathing
Think clearly
Describe the situation to topside
Determine the cause of fouling and, if possible, clear themselves
Be careful to avoid cutting portions of the umbilical assembly
when using a knife or other cutting implement
• If efforts to clear themselves are unsuccessful, divers
should call for the standby diver then wait calmly for
their arrival
Diver Emergencies: Blowup
• Blowup is the uncontrolled ascent of a diver from depth
• Blowup can result when a drysuit becomes over inflated;
the diver loses control of their buoyancy; as a result of
entanglement with equipment moving toward the
surface; when excess drag on the umbilical by current
sweep the diver toward the surface; etc.
• Blowup can cause:
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Arterial gas embolism
Decompression sickness
Missed decompression stops
Physical injury (striking objects in the water column or the
diving platform)
Diver Emergencies: Blowup
• After surfacing, blowup victims should not be
allowed to resume diving
• If a diver who has experienced a blowup
appears to have no ill effects and is still within
the no decompression limits of the dive tables
used, s/he should return to a depth of 10 feet (3
m) and decompress for the amount of time
normally required to ascend from the diver’s
working depth
• Upon surfacing the diver should be observed for
at least an hour for signs of decompression
sickness or other injuries
Diver Emergencies: Blowup
• Blowup victims who are close to no
decompression limits, or requiring
decompression, may be able to follow
surface decompression procedures, or
may require chamber treatment
• Appropriate emergency response actions
should be initiated
Diver Emergencies:
Loss of Primary Air Supply
• Loss of the primary gas supply is possible but
unlikely
• If it happens the person operating the gas
control system should immediately switch to the
secondary gas source and notify the diving
supervisor
• As the problem is being investigated,
perpetrations to recall the diver should be
initiated:
– The tender is directed to remove slack from the
umbilical and the diver is directed to assure the
umbilical is clear in anticipation of the diving
supervisor calling for the dive to be aborted
Diver Emergencies:
Loss of Primary Air Supply
• The procedure for a diver reporting low gas flow or the
helmet or mask breathing hard is to have the operator to
check the supply console;
• If supply gas pressure is adequate, the problem may be
along the umbilical
• The diver should switch to the bailout; if gas flow
improves the diver should check to insure the umbilical
is clear
• It may become necessary for the supervisor to call an
abort to the dive or to deploy a standby diver with a
spare umbilical and tools to switch out the fouled
umbilical
• Never continue a dive with only one gas source
Diver Emergencies:
Loss of Communication or Contact
• If hard-wire communication is lost, the
tender should immediately attempt to
communicate with the diver by line-pull
signals
• If the diver responds, and depending on
diving conditions and the arrangements
made during dive planning, the dive may
either be terminated or continued using
line-pull signals
Diver Emergencies:
Loss of Communication or Contact
• If the diver does not respond, the tender
should take up additional strain on the
umbilical and repeat the line-pull signal
• If the diver continues to be unresponsive
the standby diver should be deployed and
appropriate actions taken depending of
the situation
Diver Emergencies: Falling
• Falling is a serious hazard for
divers using free-flow helmets or
masks
• The principle danger is the
sudden increase in ambient
pressure resulting in a squeeze if
the diver cannot immediately
compensate by adding gas
• The tender must always be alert
to the possibility of a fall and
should take strain on the
umbilical to stop the diver’s
descent should a fall occur
Ascent
• The diving supervisor
will order the diver
back to the stage/bell
or descent line when
the diver’s bottom
time has expired or
the task has been
completed
Ascent
• During the ascent the following procedures
should be used:
– The tender should exert a slight strain on the
umbilical assembly
– The tender should exert a slow, steady pull, as
directed by the diving supervisor
– The diving supervisor starts timing the ascent as soon
as the diver indicates leaving the bottom
– The consol operator monitors the divers depth via the
pneumofathometer hose and relays information to
the diving supervisor
Ascent
• Ascent procedures continued:
– If diving a drysuit, the diver will bleed gas as
necessary to avoid a blowup
– Generally, the supervisor will inform the diver well in
advance of decompression requirements
– When the diver surfaces, the tender and topside
personnel help the diver to the dressing bench where
the helmet or mask is removed, followed by the
remaining equipment
Post-dive Procedures
• After all equipment has been removed and been checked
by the diving supervisor, the diver should remain in the
general vicinity for at least 30 minutes
• If diving operations are concluded:
– Clean the helmet or mask and emergency gas system; rinse
thoroughly, and blow down with air
– Secure the gas supply to the helmet or mask; disconnect and cap,
or bag exposed fittings
– Clean and rinse all diving equipment
– Blow down the diver’s umbilical, disconnect, and stow
– Ensure the dive control system has been properly secured
• Post-dive maintenance includes cleaning the interior of
the mask or helmet with a disinfecting solution in
accordance with manufacturer recommendations
Umbilical Diving from
Small Boats
• Although most surface-supplied diving is
conducted from large vessels or fixed platforms,
the umbilical system can be adapted to small
boat operations
• A minimum two-point moor is recommended to
help prevent the craft entangling the diver
• High pressure cylinders attached to the gas
control system are more commonly used than
compressor systems and volume tanks for small
boat surface-supplied operations
Umbilical Diving from
Small Boats
• Generally, it is wise to limit diving depths to less than
100 ft (31 m) when working from a small boat
• The dive team for a surface-supplied dive from a small
boat consists of a diving supervisor, a diver, tender and
standby diver
• Sufficient cross-training of personnel to allow for
emergency/contingency situations is a must
• The standby diver can be equipped for a surfacesupplied dive or can be equipped with scuba; s/he
should be capable of donning scuba and entering the
water in less than one minute
• A standby diver using scuba should be fitted with a
quick-release lifeline, or hard-wire communication line
(readily releasable in the event of entanglement)
Supply Pressure Requirements
• Free-Flow Systems
– Many factors can influence gas flow when using a
free-flow mask or helmet; length and inside diameter
of umbilical, number of umbilical couplings, supply
valve restrictions, and supply pressure
– When diving to depths up to 120 fsw (37 msw), it is
recommended that umbilical pressure be at least 50
psi over ambient pressure
– When diving to depths in excess of 120 fsw (37 msw),
it is recommended that the supply pressure be at least
100 psi over ambient pressure
Supply Pressure Requirements
• To calculate supply pressure for free-flow
systems for depths less than 120 fsw:
Ps = 0.445D + 65
• Where:
– Ps = supply pressure in psig
– D = depth in fsw
– 65 = absolute hose pressure (50 psi +14.7)
Supply Pressure Requirements
• To calculate supply pressure for free-flow
systems for depths greater than 120 fsw:
Ps = 0.445D + 115
• Where:
– Ps = supply pressure in psig
– D = depth in fsw
– 115 = absolute hose pressure (100 psi +14.7)
Supply Pressure Requirements
• Demand Systems
– Demand-mode diving generally requires
higher supply pressures, but the overall gas
usage is less than that of free-flow diving
– The need for great quantities of gas to ensure
low levels of CO2 is eliminated due to the use
of oral-nasal masks or very small oral cavities
– The actual pressure needed to allow a helmet
or mask to work efficiently is dictated by the
manufacturer
Supply Pressure Requirements
• To calculate supply pressure for demand
systems:
Ps = 0.445D + MRPOA
• Where:
– Ps = supply pressure in psig
– D = depth in fsw
– MRPOA = manufacturer’s recommended
pressure over ambient
Supply Pressure Requirements
• It must be remembered when computing the
flow requirements, the actual flow will be
influenced by mechanical restrictions in the
system
• For example; the flow at the diver’s end of a
single 300 ft umbilical would be greater than the
flow through two 150 ft umbilicals coupled
together
• Some manufacturers will provide guidelines for
surface-supply control consoles and umbilical
configurations
Study Questions
• Use the following study questions to
review some of the information presented
in this self study module
• When you are finished you can print out
your study questions results