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ST53 – The total respiratory protection system

The ST53 combines Avon Protection's FM53 mask technology with an advanced modular breathing apparatus to provide positive pressure SCBA and/or PAPR capability for specialist operations.
Developed with the unknown elements of a threat scenario in mind, the ST53™ is the most advanced CBRN respiratory solution on the market.  It enables a fast response to changing operational conditions in one complete modular system.
A switch between negative (filter) and positive (SCBA) pressure is achieved at the flick of a lever on the front of the mask. And by attaching a short or long duration compressed air cylinder, it is possible to enter a location on filter mode, assess the situation and change to SCBA mode if the need arises.

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st53 brochure

For further information
please download the ST53 brochure


Features & Benefits

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Compact Demand Valve (CDV)

  • 1st breath activated for “instant on”
  • Rugged, compact design delivers high flow rates
  • Screw-on-design allows for DIN 40 thread
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Gauge & Whistle

  • Located on shoulder straps for easy access
  • Positioned for high noise environments and easy gauge reading
  • Illuminated gauge for low-light situations
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Stealth Appearance

  • Black low profile design
  • Lightweight compared to traditional SCBA units
  • Silent operation for critical missions 
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  • Ergonomically contoured backframe for comfort
  • Adjustable harness allows for quick donning / doffing
  • Padded shoulder straps for comfort

Technical Spec

Breathing performance in SCBA mode
Breathing Rate 103 liters per minute with mask pressure above ambient
Environmental range The operating range is -30oC + 60oC
End of cylinder air Able to sustain positive pressure down to 10 bar cylinder pressure
Breathing Performance in ST PAPR mode Breathing rate 125 - 165 liters per minute
Breathing performance in APR mode
Breathing resistance Exhalation breathing resistance of no greater than 20mm of water at 85 lpm in a negative pressure mode
Inhalation resistance including General Purpose filter 50 mm of water at 85 lpm
Live agent permeation performance (Data validated by ECBC, Edgewood Chemical Biological Center)
  Requirements Actual Test agent NIOSH CBRN requirements Typical performance
Challenge chemical Max Peak (mg/m3) Max Cumulative (mg-min/m3) Max Peak (mg-m3) Max Cumulative (mg-min/m3 )
Sarin (GB) 0.6 6 0.004 0.203 Mustard (HD) 6 Hours > 6 Hours
Mustard (HD) 0.087 6 0.005 0.8 Sarin (GB) 6 Hours > 6 Hours
Materials used
Harness on ST53 SCBA Kevlar webbing with stainless steel nylon hardware
Harness on ST53SD SCBA Nylon Cordura
Backplate Glass reinforced polycarbonate
Cylinder valve Anodized Aluminum
ST-PAPR GE Noryl with a 10% glass fill
Weight for ST53 units (based on empty cylinders) Weight for ST53SD units (based on empty cylinders)
ST53 (excluding cylinder and mask) 6.6 lbs ST53SD 11 cu. ft (includes cylinder but no mask) 5.2 lbs
Carbon fiber fully wrapped, 2216 psi, 30 minute 7.75 lbs
Carbon fiber fully wrapped, 4500 psi, 30 minute 7.4 lbs
Carbon fiber fully wrapped, 4500 psi, 45 minute 9.9 lbs ST53SD 17 cu. ft (includes cylinder but no mask) 4.0 lbs
Carbon fiber fully wrapped, 4500 psi, 60 minute 11.95 lbs
Weight for ST-PAPR Weight for mask only
ST-PAPR without CDV, battery or cartridges 2.5 lbs Single Port FM53 mask (excluding filter) 1.2 lbs
ST-PAPR without CDV, two general purpose filters and a lithium Sulphur Dioxide battery 4.4 lbs Dual Port FM53 mask (excluding filter) 1.3 lbs


  • CE Type-Examination conducted by BSI. The system has been certified to the requirements of the PPE directive 89/686/EEC (certificate number CE 564330)
  • The Avon ST53 SCBA carries a NIOSH Industrial Approval under the provisions of 42 CFR 84 TC-13F in a variety of cylinder and facepiece size combinations.


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