Medical gas flowmeters are among the most-used devices in any healthcare facility. They control and display the flow of oxygen or medical air to patients via nasal cannulas, masks and nebulizers, so an inaccurate or damaged flowmeter directly affects therapy. This guide covers the types of medical gas flow meters, how to inspect and maintain them, and when to replace them.
What a medical gas flowmeter does
A flowmeter connects to a wall outlet (or a cylinder regulator) and lets clinicians set a flow rate, usually in liters per minute (LPM). It reduces pipeline flow to a precise, adjustable rate and shows that rate on a scale.
Types of medical gas flow meters
- Thorpe tube (ball-in-tube) flowmeters – a float rises in a tapered tube; pressure-compensated models read accurately when connected to pipeline pressure
- Dial or click-style (fixed orifice) flowmeters – select preset flow rates; durable and easy to read, common for transport and home use
- Low-flow and pediatric/neonatal flowmeters – fine-resolution scales for small flow rates
- High-flow flowmeters – for high-flow therapy and specific devices
- Dual flowmeters – two flowmeters on one outlet connection
Flowmeters are gas-specific (oxygen flowmeters are typically green, medical air yellow in the U.S.) and come with connectors for the facility’s outlet style: DISS, Chemetron, Ohmeda or Puritan Bennett. See flowmeters and our medical gas products.
How to inspect a flowmeter
Clinical engineering or facilities staff should include flowmeters in routine equipment checks. A basic inspection:
- Visual check: look for cracked or cloudy tubes, missing or damaged knobs, damaged labels and debris.
- Correct gas and connector: confirm the color code, labeling and outlet connector match the gas service.
- Zero check: with the knob closed and connected to the outlet, the float should rest at zero and there should be no flow.
- Leak check: listen for hissing at the connection and body; use an approved leak-detection solution if needed.
- Accuracy check: compare indicated flow against a calibrated flow analyzer at several settings, following manufacturer tolerances.
- Control function: the knob should adjust smoothly and hold its setting.
Maintenance best practices
- Follow the manufacturer’s inspection and accuracy-check intervals
- Clean exteriors with approved disinfectants that won’t cloud or crack the tube
- Never lubricate oxygen equipment with oil or grease
- Remove damaged or inaccurate units from service immediately and tag them
- Keep spares of each outlet style so rooms aren’t left without flowmeters
- Check the outlets too: a worn outlet can leak or fail to latch even with a good flowmeter
When to replace a flowmeter
- Cracked, scratched or cloudy flow tubes that are hard to read
- Readings outside the manufacturer’s accuracy tolerance
- Leaks that can’t be corrected
- Sticking floats or knobs that won’t hold a setting
- Connectors that don’t match your facility’s outlets after a renovation
FAQs
What’s the difference between a pressure-compensated and uncompensated flowmeter?
Pressure-compensated flowmeters are calibrated at the outlet pressure and read accurately even with downstream resistance (such as a humidifier). Uncompensated models can read low when back pressure is present. Most hospital pipeline flowmeters are pressure-compensated.
Are oxygen and air flowmeters interchangeable?
No. Flowmeters are calibrated for a specific gas and use gas-specific connectors to prevent misconnection.
How often should medical gas flowmeters be checked?
Follow the manufacturer’s recommendations and your facility’s equipment management program. Many facilities do visual checks with each use and periodic accuracy checks as part of preventive maintenance.
Need flowmeters, outlets or regulators? Call 714-897-7530 or email info@medicalgasresources.com.
