Bulk Oxygen High Use Management
ACTION ITEMS:
Increase the delivery pressure from the bulk oxygen to 55 psi. Then monitor the pressure in high-risk areas. If the pressure drops to 40 psi, there will be a low pressure alarm.
If you want to know the maximum delivery flow available for an area, insert an oxygen flowmeter into every available oxygen outlet and tabulate the accumulated flow until the pressure drop for the zone drops to 45 psi.
Monitor the bulk oxygen delivery pressure and the vaporizer icing.
Develop a clear understanding with your medical gas supplier regarding the filling of the bulk oxygen, their ability to supplement the bulk oxygen supply and their delivery of oxygen tanks to RT.
When there is high usage of the medical oxygen in a hospital there will be signs of high use at the bulk oxygen station. The key point here is to monitor the ice on the evaporators and coordinate with the bulk oxygen supplier to mitigate icing.
If you know how the bulk station works, then you can create a plan to monitor it and maintain it.
Icing - Normal and Abnormal
Remedies to Icing
Daily Performance Logs
Icing - Normal and Abnormal, Normal icing can occur around the economizer located directly under the tank. It can also be normal for some vaporizers to ice due to changes in weather, environmental changes such as a new structure blocking the sun or the addition of oxygen outlets within the facility. When an increase in ice is noticed, that is the time to investigate to determine if it is problematic. Abnormal icing can occur when there is excessive demand from the facility or when there is a leak in the bulk system piping. If there is a leak, contact the bulk oxygen service company. A leak can be identified by an abnormal accumulation of ice on pipes leading to the evaporator or pipe on the vessel. If it is abnormal icing of the vaporizers there are a couple of remedies.
Remedies to Icing of the vaporizers. Vaporizers are installed in a redundant fashion. There is a switchover valve that allows you to choose which one is in service. During periods of high use it is recommended to change the IN-Use vaporizers more often. If there is no regular procedure for this, start with changing the vaporizer in-service every 12 hours. If icing continues to be a problem, change that period to every 6 hours. If one of them is over icing and alternating vaporizers does not make an improvement, use the changeover switch to put the backup vaporizer online. Then allow the iced vaporizer to thaw. If over icing becomes unmanageable using switchover, deicing can be used. Consult with your bulk oxygen service company before doing this. Power washing with heated water is a remedy. There are professional services that can do this.
Daily Performance Logs should be kept. They should include pressure readings, liquid level readings and a record of the visual inspection for ice. Any evidence of frost starting to form on the pipes exiting the vaporizer should be considered serious and remediation should start immediately. Ice buildup beyond the vaporizer, such as in the area of the switchover valve or the delivery regulators can impact the delivery of oxygen to the facility.
The operation of a bulk oxygen system involves changing the stored liquid oxygen into usable gaseous oxygen. This is a simple process because the very cold liquid oxygen wants to become gaseous just like the ambient air that surrounds its vacuum sealed container. To accelerate that process a vaporizer is used to provide more surface area to transfer ambient heat to the liquid oxygen flowing through it.
In addition, two vaporizers are provided in the event that one becomes overcome by ice that reduces the efficiency of the vaporizer.
A Switchover Valve is provided to either manually switch from one vaporizer to the other or in some cases there is an automatic switchover that switches vaporizers automatically by a timer. If there is an automatic switchover valve, it has a manual over-ride.
The diagram show the flow of liquid oxygen, in blue, and gaseous oxygen, in green. The oxygen enters the vaporizers as a liquid and leaves the vaporizer as a gas. It then goes through a regulator manifold shown here as a simple single line regulator and then to the hospital.
Problems occur when portions of the system accumulate to much ice. For most systems a certain amount of icing is normal. When an increase in ice is noticed, that is the time to investigate to determine if it is problematic. Normal icing could be around the economizer located under the tank and the vaporizers during times of high demand or cold weather.
The first line of defense in icing of a vaporizer is to use the switchover valve to move the flow over to the vaporizer that was not in use.
An area of great concern would be any frost that appears on either of the pipes that connect the vaporizers to the switchover valve.
Preventative maintenance would include daily visual inspections noting the level of icing in any areas of icing and delivery gauge readings.
Preventative deicing measures can be performed. It is recommended to always consult with the bulk system maintenance provider for any maintenance. There are professional high pressure services that provide hot to warm water high pressure to removed ice.
