Dräger SMS 1 semiclosed-rebreather

Hose dependent Mixgas Swimmdive unit

This rebreather is equipped with a 1 liters backup cylinder filled with 200 bar.o The Constant Mass Flow will work to max 40 bar, therefore 160 liter gas is available. Since 8 min dive time is referred to the flow will be 20 ltr/min of nitrox 17,5.
Presuming the diver is @ 200 meter and using his emergency bailout with a metabolic use of 1,5 liters of oxygen per minute the half closed quotation gives a FiO2 of (20l/minx0,175)-1,5 / 20l/min – 1,5 = 0,108 % resulting of a 2,27 bar pO2 at depth. This is a very high PO2 that was adjusted downwards in later years. The small compact unit was a so-called tethered unit and the successor to the SM1 – SMIII series.

DATASHEET SEMICLOSED REBREATHER
SMS I	Date: 01 November 2005
Schlauchabhängiges-Mischgas-Schwimmtauchgerat (Hose dependent – Mixgas – Swimdiveunit)	Database semi closed rebreathers by: J.W. Bech
Manufacturer	Dräger	(name or company)
Designer		(name)
Model	SMS1	(number type)
Land of origin	Germany	(country)
Design year	1969-1970	(actual project start)
Special Note:	Variant See SMS 1/B	(additional space for info)
User group	Military	(sport/mil/civil/fire)
Magnetic characteristics		(if known)
Part no:	T11 111	(part #)
Working principle	Constant Mass Flow	(CMF/Metering,Passive)
Gas type	Heliox 17,5/82,5	(Heliox/Nitrox)
Gas mix type	% Oxygen	% Helium	Flow	Worktime	Depth
(backup) Heliox	17,5	82,5		8 min	200m
1 liters backup cylinder filled with 200 bar.o The CMF will work to max 40 bar, therefore 160 liter gas is available. Since 8 min dive time is referred to the flow will be 20 ltr/min. Presuming the diver is @ 200 meter and using his emergency bailout with a metabolic use of 1,5 liters of oxygen per minute the half closed quotation gives a FiO2 of (20l/minx0,175)-1,5 / 20l/min – 1,5 = 0,108 % resulting of a 2,27 bar pO2 at depth.
Intended use	From dive bell or UW lab.	Sport/MC/Deep/Tethered
Dimensions LxWxH	500x420x160 mm	(outside in mm)
Device weight	14 kilo	(filled+gas on land)
Intermediate Pressure		(IP )
Overpressure valve	11 cm – 17 cm WK adjustable	Range
Max depth	200	(mtr)
Used material for housing/backplate	glasfibre
Pressure reducer	Membrane type	Membrane / Mushroom
Connection reducer – bottles	M22 x 1,5
Supply pressure	200 bar, minimum 30 bar
Umbilical connection	Yes/No
Manual bypass	Yes/No
pO2 measurement standard	Yes/No
Pressure gauge range	?
Cylinders	1 litre
Cylinder material	Steel
Cylinder thread	M22 x 1,5
Valve	–
Designed for gas mix	17,5 / 82,5 heliox
Co2 absorption cartridge capacity	2,5 liters	(early square form!)
Co2 absorption cartridge rechargeable	Yes by the diver
Co2 absorption cartridge storage time	–	(month/year)
Co2 absorption time testing (CE)	Not CE
Connections Co2 cartridge	screw
Guaranteed absorption time	3 hours
Grade of absorption material	dragersorb
Breathing bag material	Reinforced rubber
Inhale bag volume	5,5 liters
Exhale bag volume	Total = 5,5
Total loop Volume	Total volume ~8,5 liters
Operating temperature	–
Magnetic signature	–
Colour (s)	Yellow
Worn	On the back
FFM attached	NO	(mask)
Mouthpiece valve	Yes
Extra info:
Additional information:
Email address owner:
URL owner:
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!
Info found:
Origin: http://www.therebreathersite.nl
Info: http://www.therebreathersite.nl/jan_jahn_sms_1.htm
Or: https://newwebsite2019.therebreathersite.eu/jan-jahns-sms-1/ Important features: Gas supply via umbilical located in diving bell Mixed gas prepared in diving bell by means of the unit MVB (III) Build in bailout system consisting of: Pressure reducer – CMF valve – Mix gas bottle of 1 liters\ Low breathing resistance due to large diameter hoses Scrubber with low resistance for W.O.B and water lock All parts are build in the housing made of glass fibre, worn on the back Separated inhale and exhale counterlung, resulting in a cleaner scrubber bed. Low resistance in the water due to compact form and small measurements of the unit. Easy maintenance by replaceable parts

This rare rebreather was designed back in the early 1960s and was used for deep-sea operations offshore and for military purposes. As documentation is narrowly available a call to anyone who has information to add to this document to send it to me. I can then add it and keep it for the readers of my website!

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