Portable oxygen tanks allow individuals requiring supplemental oxygen to maintain mobility. These systems primarily come in two forms: compressed gas cylinders and portable liquid oxygen (LOX) units. Following the correct shut-off procedure is paramount for user safety and to prevent accidental oxygen wastage. Neglecting these steps can lead to a hazardous buildup of gas or the premature depletion of the oxygen supply.
Safety First: Essential Steps Before Shutting Down
Before initiating the shut-down process on any portable oxygen device, several preparatory steps must be completed. First, the user must confirm that the oxygen therapy session is fully concluded and that they no longer require the supplemental flow.
Next, the flow control setting on the regulator or conserver device must be turned to the “OFF” or “0” position. This action immediately halts the oxygen flow delivered through the nasal cannula or mask, conserving the remaining gas inside the tank. The device should be secured in its cart or stand to prevent it from tipping or rolling during the shut-off process. Finally, removing the cannula or mask from the user completes the pre-shutoff procedure.
Turning Off Compressed Gas Cylinders
Compressed gas cylinders store oxygen under high pressure and utilize a main valve to control gas release. To safely turn off the cylinder, the user must first locate the main cylinder valve, usually found at the top of the tank. For many portable models, this valve is a small handle or a square post requiring a cylinder wrench to operate.
The valve must be turned in a clockwise direction—the “righty-tighty” rule—to fully close the flow of oxygen from the tank. It is important to close the valve completely but to avoid overtightening, which could damage the valve seat. Once the main valve is closed, the next action is to “bleed” the system by opening the flow regulator knob again.
This bleeding step releases the residual, pressurized oxygen trapped between the closed main valve and the regulator, causing the pressure gauge needle to drop to zero. After the gauge reads zero, the flow regulator knob should be closed tightly to prevent dust and debris from entering the system. This sequence of closing the main valve first and then bleeding the regulator ensures the entire system is safely depressurized.
Shutting Down Portable Liquid Oxygen Units
Portable liquid oxygen (LOX) units store oxygen in a cryogenic, liquid state, requiring a distinct shut-off procedure. Unlike compressed gas tanks, LOX portables often employ a lever or a specific button to control the internal valve, rather than a simple rotary knob. Users must consult manufacturer’s instructions for the exact location and operation of this shut-off mechanism.
Even after the main valve is closed, LOX systems may continue to release small amounts of oxygen, which is a normal process called venting. This venting manages the pressure that naturally builds up inside the tank as the liquid oxygen warms and converts back into a gas. This design feature prevents an unsafe internal pressure increase, but it means the unit is never completely sealed and should be kept in a well-ventilated area.
Troubleshooting: When the Tank Won’t Turn Off
A primary safety concern arises if the main valve on a compressed gas cylinder becomes stuck and will not turn clockwise to shut off the flow. Do not use excessive force or tools not designed for the valve, as this could cause damage to the regulator or valve assembly.
If a leak is detected, such as a persistent hissing sound after the main valve is closed, immediately move the tank away from open flames, sources of heat, or sparks. Increasing the ventilation in the area by opening windows and doors is also a necessary immediate action to dissipate the oxygen-rich air. If the valve is stuck or a leak persists, contact the oxygen supplier immediately for technical support or equipment replacement.
If the pressure gauge needle fails to drop to zero after completing the shut-off and bleeding procedure, the main valve is likely not fully closed. The user should attempt to turn the main valve slightly more clockwise, being careful not to over-tighten, and then re-check the pressure gauge. Never attempt to use or store a tank that is leaking or one where the shut-off procedure cannot be fully executed, as this constitutes a fire hazard.