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FAQs

FAQs
Air Supplied
Q1 It is possible to wear a face mask with facial hair?
A1 Generally not. A good face seal will only be obtained if the skin in the region of the seal is smooth and without hair. Facial hair tends to lift the mask off the face and permit inward leakage of contaminated air.
Q2 Is it possible to wear prescription spectacles with a facemask?
A2 Spectacles with side arms are incompatible with full-face masks. Side arms interfere with the face seal and can cause serious leakage. There are special designs of spectacle frames to fit inside facemasks.
Q3 Do you need a fit test for a hood?
A3 According to HSE guidelines, loose fitting hoods do not require any form of fit testing.
Q5 Can ELSA cylinders be filled on site?
A5 Cylinders may be refilled on site at any time with the appropriate compressor. Otherwise see approved service centres here.
Q6 What is the life span of a carbon fibre cylinder?
A6 Carbon Fibre Cylinders have a 15 years design life from the date of manufacture (which should be written on a band around the cylinder). The cylinders must be hydrostatically tested every 5 years.
Q7 What is the life span of a steel cylinder?
A7 These have a theoretically infinite lifespan as long as they continue to pass the 5 yearly hydrostatic test.
Q8 How is the duration of a cylinder worked out?
A8 To calculate approximate cylinder duration:
Multiply the cylinder volume by the cylinder pressure (in bar) and then multiply this by the compression factor (see below for explanation of compression factor).

This gives the volume of air in the cylinder which can be divided by the breathing rate (litres per minute, nominally taken to be 40lpm) to give you approximated cylinder duration.

Cylinder Volume x Cylinder Pressure x Compression Factor = Volume of Air (litres)
Volume of Air / 40 = Approximated cylinder duration (minutes)
Q9 What is “Compression Factor”?
A9 When air is compressed to higher pressures it does not compress in a linear manner. Therefore a compressibility factor is applied when calculating the volume of air present.

At 200 bar the relationship between volume & pressure is as near as linear so the compressibility factor is 1. At 300 bar the compressibility factor is 0.91 and at higher pressures this factor will become lower.

So for a 200 bar cylinder Volume x Pressure x 1 = Volume of Air
And for 300 bar cylinder Volume x Pressure x 0.91 = Volume of Air
Q10 What pressure and flow should I have at the end of an airline for positive pressure sets?
A10 Pressure should be above 4 bar and the flow for one user 300lpm (for two users 450lpm between them).
Q11 What is the maximum length of hose I can use with a Modul + Air II?
A11 105 metres
Q12 What are the torque settings for the various cylinders?
A12
Valve/cylinder type
Torque (Nm)
Parallel thread valves in steel / aluminium / fibre wrapped cylinders.Thread size M18
70 +/- 10
Thread size M25
90 +/- 10
Tapered thread valves in steel cylinders
105 +/- 5
Q13 How often should a compressor have an air quality test done?
A13 According to COSSH Regulation 9 (Approved Code of Practice) 178:

“The quality of the air supplied to breathing apparatus should be tested at least once every 3 months and more frequently when the quality of the air cannot be assured. Where the air supply is from mobile compressors, the employer should ensure that wherever a compressor is located, the quality of air it supplies is not compromised by nearby contaminants”