What is Long Duration Breathing Apparatus?
Long Duration Breathing Apparatus is a type of Breathing Air System where the user/s require breathable air for a sustained period of time. These are usually fed via an airline, in a situation where a Self-Contained Breathing Apparatus Set isn’t suitable.
Different types of BA systems and choosing the right one for you Although there are various types of systems suitable for different applications, some of the most common systems in the market include:
Breathing Air Trolley i.e. Scott Modulair/Drager Colt/ATS Trolley
Breathing Air Trailer i.e. BA Trailer
Breathing Air Compressor i.e. BAC Compressor or BreatheBlast
Both High or Medium Pressure Compressors
Life Support Systems i.e. Luno LSS System
BA Cascade systems
For more information about the main advantages/ disadvantages for each type of system, please see our previous blog post.
One consideration is, although you may have a permanent requirement for breathing air, if you are using the system for multiple locations, even on the same site, it may be more cost effective to look at a portable option which provides greater flexibility.
How do I calculate how much Breathing Air I need or have for the job task/ project?
To calculate the air you have, you can use the same formula as with any BA System:
Water Capacity (Size of Cylinder) Litres x Number of Cylinders = Overall Capacity
Overall Capacity x Charge Pressure (200 or 300bar if full) x Compressibility Factor (200bar – 0.96 or 300bar - 0.92) = Total Number of Litres
Total Number of Litres ÷ Average Consumption per User (40litres/min) = Overall Duration of Air Source
Overall number of minutes – 10% Emergency Air = Total Working Time
Total Working Time ÷ Number of Users = Working Time per User.
If you have a specific project which you are looking to calculate how much air is required, you can reverse the above formula:
Average Consumption per User (40litres/min) x Number of Users x Number of Minutes Working = Overall Litres of Air Required
Overall Litres of Air Required + 10% Emergency Air = Overall Duration Required.
Overall Duration Required x Pressure of Compressed Air (usually 200 or 300bar) = Number of Compressed Litres of Air Required.
What else should I consider when calculating how much air/ which system I need?
Size of Air Trailers/ Air Source available (Some examples from our hire fleet include: Mini4, Midi8, Maxi12 Breathing Air Trailers, Cylinder Trolley or Modulair Trolley)
The length of Airlines for the job - there will also be an amount of air wasted within the system to account for.
40L/min is only a guidance for the amount of air consumed with a positive pressure BA mask, other factors that may affect this include: any possible leaks, BMI of users, if the users bypass the lung demand valve onto free flow, in an emergency situation users are likely to have a higher breathing rate, work rate and atmospheric temperature.
Would using a Breathing Air Compressor be an option? If so, this would eliminate the need of calculating durations.
How far away from the Mobile Air Compressor or Trailer can I work?
Although this would need to be checked for each system specification, most people are used to working up to 90 metres away from any trailer as an existing proven concept. As manufacturers ourselves, we have tested and proven our mobile trailers and/or compressors can supply up to eight users simultaneously with 150M of airline each from the removable control panel situated 25M from the unit (tested with Breathe Safety spec airlines – certificates can be provided on request).