Service and Tech Support Information

Troubleshooting 101—How to Perform a Leak Test

How to perform a basic 10-second leak test





A leak test is the basic troubleshooting technique for diagnosing a rebreathing anesthesia system for leaks. Each time you use your rebreathing anesthesia system, we recommend you check for pressure leaks in the machine and ensure that your waste-gas evacuation system is working properly.


1. Connect a rebreathing circuit and bag to your machine as if you were about to perform a surgery.
2. Close the Pop-Off Valve and cover the end of the rebreathing circuit—where the E/T tube connects—with your palm or finger.
3. Push the oxygen flush button or turn the flow meter ON until the pressure gauge reads at least 20 cmH2O.
4. Turn the oxygen OFF and watch the pressure gauge. If the reading drops rapidly (faster than 1 cmH2O per second), you have a leak.
5. Check hoses, rebreathing bag, vaporizer inlet and outlet, any mechanical fittings, and the seals of the canister for leaks. When the pressure remains fairly constant, with the flow meter turned OFF, your machine can be considered leak free.
6. With your thumb still over the y-piece, open the Pop-Off Valve to ensure the gases have an unobstructed path out of the evacuation system.
If you are unable to find a leak and your patients continue to be “light,” be sure to contact your local anesthesia service company for a service appointment. There may be issues with your vaporizer or scavenger system. Your system should be serviced by a professional.

If you are unable to find a leak and your patients continue to be “light,” be sure to contact your local anesthesia service company for a service appointment. There may be issues with your vaporizer or scavenger system. Your system should be serviced by a professional.


Problems & Solutions

Problem: “I think my anesthesia machine is leaking. I hear a hissing sound and I’m not sure where it’s coming from.”

Troubleshoot by performing a leak test. You can use Windex as you perform the test to look for bubbles that may emerge from sealed areas on the machine. IMPORTANT: Never spray petroleum products on your oxygen system.


Solution: If you find a crack in CO2 absorbing canister or the black tubing, contact the Supera Anesthesia Innovations service department. If the silicon gasket is torn, contact us to order new gasket.

If the leak is coming from the dome o-ring area, check to see whether the o-rings are seated incorrectly or cracked. Unscrew dome counterclockwise and slip o-ring off dome. Inspect for cracks. If there are cracks contact our service department to order new o-rings. If you don’t see any cracks, place o-ring on top of dome and slide down evenly until it “snaps” into place. Screw dome back into place clockwise until tight. Perform leak test again. If problem persists, contact us.

If the leak is coming from the inlet and outlet vaporizer adaptors, they may not be seated properly.

If the leak is coming from around the base of the Pop-Off Valve, remove the valve, wrap Teflon tape on the threads, and reinstall.

If the leak is coming from around the rebreathing liter bag, a common problem, check to see whether the bag is cracked or has holes, if so, remove and replace.

If the leak is coming from the rebreathing hoses, check for cracks and if needed, replace.

Retest to ensure no leaks persist.

Problem: “I am unable to keep a patient down. I set the vaporizer setting to 5% and my patient still begins to wake up.”

Troubleshoot by performing a leak test as above. If you find no leaks, check your evacuation system. If there is an imbalance between the positive and negative pressures in your anesthesia system, the anesthetic agent may be effectively removed from your system due to the vacuum effect of the evacuation device.

Check the vaporizer. It may not be outputting the percentage indicated. When vaporizers fail, they usually fail on the low side and rarely on the high side. But before sending the vaporizer in for service, please check:
• Is there anesthetic agent in the vaporizer?
• Are the manifold inlet and outlet adapters pressed snugly onto vaporizer manifold?
• Is the vaporizer’s drain tightened down?
• Is the vaporizer fill cap tightened down?

Solution: If your leak test shows bubbling, check for leak sources as above.

If you find the evacuation system is a problem, you may need a waste-gas interface device to balance the pressures, ensuring the anesthetic agent is delivered to the patient and not sucked out by the evacuation system.

If you find that the vaporizer is not leaking but you feel confident that the vaporizer is not functioning correctly, contact our service department or an authorized Supera Anesthesia Innovations service technician. You may also ship the vaporizer to a Supera Anesthesia Innovations authorized service center for cleaning and calibration.

Problem: “I think there is a leak somewhere between my oxygen tank and the flow meter on the anesthesia system, the high-pressure side of the anesthesia system.”

Troubleshoot by spraying Windex on the fittings where you hear the sound. If you have a leak, it will bubble. Here’s how:
• Turn flow meter off.
• Turn oxygen tank on so you can watch the pressure regulator rise.
• Turn oxygen tank off.

The pressure regulator should hold steady. If the pressure begins to fall, you have a leak.

Solution: Check the oxygen hose nut. If it is not fully tightened, use a crescent wrench to fully tighten.

Check the oxygen flow meter flow control assembly to ensure it is not stuck in an open position. If the ball floats and will not fall to zero, the meter is stuck. Under normal circumstances, this requires replacement of the flow control assembly. Please contact our service department.

Problem:“The oxygen doesn’t seem to be flowing or I cannot turn my oxygen off on my anesthesia machine.”

Troubleshoot by:
• Checking to make sure the oxygen tank is on
• Pushing on the oxygen flush to ensure oxygen is flowing to the machine
• Turning mechanical stop flow control and see if ball moves up and down the flow meter
• Checking to see if ball hovers above zero in the flow meter

Solution: If the oxygen flush and oxygen flow meter are not working and the oxygen tank has been turned on and does have oxygen in it, the regulator or the oxygen tank may need to be replaced.

If the ball hovers above zero and does not come to rest at the bottom of the flow tube, you will need to replace the mechanical stop flow control assembly. Contact us for further assistance.

Problem: “My oxygen system is not working correctly.”

Troubleshoot by checking:
• The oxygen quick disconnects
• The oxygen check valves in dual gas supply
• The black tubing
• The oxygen flush
• For an oxygen leak from regulator
• For improper or insufficient oxygen flush
• For improper or insufficient metabolic oxygen delivered to patient

Solution: If no problem is apparent in any of the above, yet you are getting either pressure that is too high or too low, you may need to replace the regulator. The oxygen regulator is a medical grade, preset, non-adjustable regulator designed to reduce oxygen tank pressure from approximately 2100 psi (when full) to approximately 50 psi. If pressure is either too high or too low, your regulator may have failed.

Problem: “The needle on my monometer gauge is not at zero.”

Solution: The re-zero screw is located at the 12 o’clock position (top, dead-center) under the crystal manometer cover. Remove cover by turning counterclockwise. Adjust screw mechanism with small screwdriver until needle is zeroed. Replace manometer cover.

If manometer will not re-zero, or if needle will not indicate proper pressure, manometer should be replaced. Contact us for further assistance.