In hospitals, flow meters measure the flow of oxygen to the patient's mask or cannula, the plastic tubing with two prongs that fit in the nostrils. You will see the flow meter attached to the hospital wall since hospitals usually have a central oxygen supply. Flow meters also sit on the front of oxygen concentrators and display in volumetric units of litres per minute (L/min), the true volume flow of gas leaving the flow meter; or standard litres per minute (Std L/min), which represents how the air would move if the pressure and temperature existed at standard conditions.
Place the oxygen concentrator in an upright position for an accurate reading and turn on the power.
Watch the black or red float move up. On the flow meter, pressurised air enters through the inlet port and exits through the outlet port. The moving air will push and lift the float up.
Notice the calibrated scale on the front of the flow meter. This scale helps you read the flow rate. The very centre of the float gives you the measurement you want. If the centre of the float reads "2" on the scale, this means you will receive a continuous flow rate of 2 litres per minute of 90 to 95 per cent oxygen.
Never change the flow rate yourself. You can receive serious side effects. Contact your doctor first, then your oxygen tank or concentrator supplier if you feel you must have more oxygen.