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DATASHEET OXYGEN REBREATHER
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SEFA
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Date: 13 April 2003 |
Selected
Elevated Flow Apparatus
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JW. Bech
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Manufacturer |
Sabre |
1985 |
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Model
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Sefa |
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Land of
origin |
United
Kingdom |
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Special
Note: |
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User
group |
Firefighters/Rescue/Mines |
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Part
no: |
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Working principle |
CMF low
5 ltr/min high 10 ltr/min |
No
demand Valve |
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Gas type |
Oxygen |
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Cylinder volume |
750 ltr |
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Max. cylinder pressure
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3.000
PSI |
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Material of cylinder
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steel |
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Counterlung inspire |
6
liters |
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Counterlung exhale |
non |
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Dive time duration |
2 hours
(approval 1 hour) |
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Operating temperature
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Hot ;) |
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Magnetic signature |
- |
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Weight ready to use in Air
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16 kilo |
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Weight ready to use in water
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- |
Not for
UW use |
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MOD |
- |
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Scrubber material |
SefaSorb |
Calcium hydroxide |
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Colour |
Black-Aluminium |
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Price |
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Worn |
Back
mounted |
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Mouthpiece |
FFM
dual hose |
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Backpack |
- |
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Extra |
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Extra |
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Overpressure valve upstream of
the canister |
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Build in heat exchanger |
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If you
have any information to add this sheet please mail it to
jw.bech@quicknet.nl
References to source and names will always be added!
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Info found: |
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Origin:
http://www.therebreathersite.nl |
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Info:
http://www.healeyhero.fsnet.co.uk/rescue/com/blenk/blenk_rescue.htm
http://www.cdc.gov/niosh/mining/pubs/pdfs/ri9650.pdf
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- The SEFA (Selected Elevated Flow Apparatus)
(figures
- 20-21) is a compressed-O2,
positive-pressure, closed-circuit
- apparatus with a refillable CO2-absorbent
canister. It
- was approved by the U.K. Health and Safety
Executive in 1985
- as a 2-hr apparatus in its low-flow mode, with
a constant flow
- of O2
of 5 L/min ATPD. In its high-flow mode—10
L/min
- ATPD—it is certified for 1-hr duration. It
contains 750 L
- ATPD of O2
at a pressure of 3,000 psi at room
temperature. It
- has no demand valve. The pressure-activated
relief valve is
- located upstream of the canister, venting
exhaled air before it
- has been cleansed of CO2
or enriched with O2.
The CO2-
- absorbent canister is filled with SEFAsorb,
consisting mostly
- of CaOH.
- The user exhales into the face mask, through an
exhalation
- check valve and hose, through the CO2-absorbent
canister, and
- through a heat exchanger to the 6-L breathing
bag, consisting of
- a spring-loaded, rigid diaphragm connected to a
flexible sleeve.
- Inhaled air is drawn from the bag, through the
inhalation
- breathing hose and check valve, then back to
the face mask.
- The heat exchanger functions in tandem with the
ambient-air
- chamber containing the breathing bag. The
volume in the
- ambient-air side of the chamber increases when
the breathing
- bag decreases, during inhalation, drawing
ambient air through
- two check valves in the panel separating the
chamber from the
- O2
cylinder compartment. Upon exhalation, the
breathing bag
- volume increases, forcing the ambient air in
the chamber out
- through the outside and core of the wetted heat
exchanger,
- drawing heat—through the evaporation of the
water as well as
- direct conduction—from the hot exhaled air
passing in the
- opposite direction through the middle plenum of
the heat
- exchanger on the way from the canister to the
breathing
- chamber. Two relief valves in the panel
separating the ambient
- air chamber from the O2
cylinder compartment permit ambient
- air in the chamber to escape if exhalation
pressure becomes
- too high.
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