Sat27November0556PM 17

A full oxygen cylinder (class CD) has an internal capacity of 2 litres and a pressure of 23,000 kPa. It is used to power a transport ventilator with an air/oxygen mix. The gas flow is 4 litres per minute.

The control of this particular ventilator has an additional gas consumption of 1 litre per minute.

Approximately how long will the cylinder take to empty?

(Please select 1 option)

55 minutes

11.5 minutes

1 hour 55 minutes

92 minutes Correct

2 hours 15 minutes

Explanation

The Drager Oxylog® 1000 is a time-cycled, volume-controlled and pressure-limited emergency ventilator that is powered pneumatically. It can be driven by oxygen in a CD cylinder.

The CD cylinder is typically made of aluminium or Kevlar making it strong and lightweight. The internal volume of the cylinder is 2 litres and a full cylinder has a pressure of 230 bar and a potential volume of oxygen of 460 litres.

The volume of oxygen in the cylinder can be calculated by applying Boyle's law:

P1 × V1 = P2 × V2

Where:

P1 is the pressure of a full cylinder (230 bar)

V1 is the volume of oxygen at that pressure (2 litres)

P2 is the final pressure (1 bar), and

V2 the volume of oxygen available.

Substituting values into the equation:

230 × 2 = 1 x V2

V2 = 460 litres.

If the fresh gas flow is 4 litres per minute + 1 litre per minute used by the control, one would expect the cylinder to last 460/5 minutes = 92 minutes.

Answer Statistics

1

15%

2

7%

3

14%

4

60%

5

6%

Times answered: 288