OzEMedicine - Wiki for Australian Emergency Medicine Doctors

see also:

• anaesthetics
• home oxygen

• Assuming the gas is stored in the cylinder in the gaseous state as medical oxygen is:
  • Boyle's law: P₁V₁ = P₂V₂
  • Look on the top of the cylinder, it should tell you how many litres when full (V₁) and the maximum pressure that should be attained when full (P₁) - this is usually ~15,000kPa
  • Look at the pressure gauge when the valve is turned on (P₂)
    • thus proportion of gas left in cylinder if volume of cylinder if unknown = P₂/P₁
  • Maximum volume of gas at atmospheric pressure when cylinder is full will be:
    • = P₁V₁/101.325
  • Remaining volume when used at atmospheric pressure (101.325kPa) will be:
    • = P₂V₂/101.325 [NB. V₂ will equal V₁ as it is still in same volume cylinder]
  • eg. a “C” size cylinder will last ~20min when used at 16-20L/min (eg. on Oxylog ventilator)

• Australian standard pin index valve for oxygen equipment
• black cylinder with white collar
• the cylinders should be labelled ‘Medical Oxygen’
• a full cylinder should have a plastic stopper inserted in the valve outlet, or if a smaller cylinder, plastic tape wound around the outlet.
• the gas is delivered through a valve to a regulating device which reduces the pressure to a safe 390-400 kPa.
• the oxygen flow is then delivered through a ‘yoke’ device that fits onto the valve stem of the cylinder. The yoke has fittings that match the valve stem, and has a measuring device attached to control the flow of oxygen.
• flow rates of oxygen are varied by either a fixed flow outlet set between 3-8 litres per minute (lpm), or by an adjustable flow meter that delivers between 1-25 lpm.
• cylinder sizes available in Australia:
  • “B” size: 200L
  • “C” size: 400-490L
    • there are various “C” size cylinders which are the most common ones used by ambulance services:
      • round bottom without long neck: 290L with brass collar, 320L without
      • round bottom with long neck: 400L
      • flat bottom: 440L
  • “Y” size: 680L
  • “D” size: 1,500-1,650L
  • “E” size: 4,000L
  • “G” size: 7,600L

• WyMedical