Wall mounted type inhaler oxygen flow meter is the most common terminal oxygen supply equipment in hospital wards, clinics, and other places.
Its pressure range also needs to be understood from two aspects: input pressure and output pressure/flow rate.
1. Input pressure
This refers to the oxygen pressure delivered from the hospital’s central oxygen supply system or pipeline to the flow meter through a wall terminal socket.
Standard range: The standard pressure for the vast majority of medical gas pipeline systems is 0.4 MPa.
Common range: generally between 0.3 and 0.5 MPa (approximately 3 to 5 bar, or 45 to 75 psi). This pressure is the stable pressure sent to the ward terminal after being adjusted by the regional pressure reducer.
Key point: The wall flowmeter itself is not a high-pressure device. It is designed to be directly connected to the already depressurized pipeline pressure. The maximum pressure that its inlet can safely withstand is within this range. If the pipeline pressure rises abnormally (such as a pressure reducing valve failure), it may damage the flow meter.
2. Output pressure and flow rate
This is the oxygen delivered to the patient after regulating the flow meter.
Output pressure: The output pressure of the wall inhaler oxygen flowmeter is very low. Its main function is to control flow, not to provide high pressure. When a patient inhales through a nasal cannula or mask, the small negative pressure generated is sufficient to extract oxygen. The output pressure is usually only slightly higher than atmospheric pressure, enough to overcome the resistance of the pipeline, usually in the range of a few centimeters of water column (cmH ₂ O), far below 1 psi. It is not an important parameter that needs to be measured or set.
Flow range: This is the most important scale on the flowmeter. By rotating the knob on the float flowmeter, the oxygen flow rate delivered to the patient can be accurately set.
Common range: usually 1 to 10 liters per minute.
Adjustable range: Some flow meters can have a minimum flow rate as low as 0.5 or 0.1 L/min (for children or special needs), and a maximum flow rate of up to 15 L/min.
Summary /Differences
For clarity, we can make a comparison with the previously discussed gas cylinder pressure reducer:
Wall type inhaler oxygen flow meter: inlet pressure
Low pressure input (~0.4 MPa), from the hospital pipeline system.
Core function: Accurately control oxygen flow rate (L/min), with very low output pressure.
Output parameters: mainly display and adjust flow rate (L/min).
Application: Hospital ward wall terminal, directly connected to patient oxygen inhalation device.
Cylinder pressure reducer
Import pressure: High pressure input (up to 15 MPa), from gas cylinders.
Core function: Reduce high voltage to safe low voltage and stabilize output.
Output parameters: mainly display and adjust the outlet pressure (MPa/psi).
Application: Connected to an oxygen cylinder as an independent or pipeline gas source for initial pressure reduction.