Sabre SEFA

Selected Elevated Flow Apparatus

Sabre SEFA

Sabre developed their SEFA (Selected Elevated Flow Apparatus) in conjunction with Mines Rescue Service. It was UK approved by the HSE in 1985.

The apparatus was a positive pressure closed circuit breathing system with options for either a CMF low flow rate of 5 litres per minute or a high flow rate of 10 litres per minute. It had a one-hour duration at 5 litres per minute and two hours at 10 litres per minute, with a total charge weight of 16 kg. Sefasorb (soda lime) was used for CO2 control.

With a 750ltr oxygen cylinder volume and built-in heat exchanger, the SEFA could also be used in water. Although if doing so in a mine roadway, a dive team would assist. All mines rescue operatives would carry out annual in-water training, assisted by the dive team. 

This apparatus became the standard in the industry from 1984 with some 500 sets being purchased and was used until 2000.

Source: https://www.mrsl.co.uk/

The company who build the SEFA rebreather is Sabre Safety (part of the Starn Group), a British specialist in respiratory protection and safety systems that plays an important historical and current role in the mining sector. Although they are currently heavily focused on the oil and gas sector, Sabre is primary known in the mining industry.

Known systems of the company are:

Sabre Sigma = SCBA

Sabre Contour = SCBA

Sabre Elsa = Escape mask

Sabre Sefa= oxygen rebreather

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.

Wanted: Sabre Sefa manual. If you have a manual for this rebreather, I would love to add it to this website.
I would greatly appreciate your contribution!

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