CPAP machines will offer different amounts of pressure between brands and the amount of pressure given to a patient will depend on their sleep apnea and how severe it is.
Those who struggle with sleep apnea normally require a CPAP pressure of around 6-14cm H2O, however, the average CPAP pressure is around 10cm H2O.
The Boussignac and Flow-Safe CPAP machines have starting oxygen flow of 15 liters per minute and can be adjusted up to an oxygen flow of 25 liters per minute. The Emergent Port O2 CPAP machine has a H2O level of 0-2cm and goes up to a maximum pressure of 10cm H2O.