Using different Gas Delivery Devices and implications

Tim Root, Assistant Head, NHS Specialist Pharmacy Service, Specialist Pharmacy ServicePublished Last updated See all updates
Topics: Medical gases

Clinical use of NIVs and HFNO and implications on pipeline capacity; the use of W-sized cylinders

The impact of the clinical use of Non-invasive Ventilators (NIV) and/or High Flow Nasal Oxygen (HFNO) on medical gas pipeline capacity

Clear clinical pathways for patients and modelling of patient needs should be developed. Areas where ventilators are to be sited and the flow rates required for patient care need to be identified. As covered in our article on supply resilience, because of pipework diameter, it may not be possible to locate all pandemic patients in the one area. It is suggested that load / stress testing (also referred to as “soak testing”) is carried out to assess capacity.
Generic usage models / calculation tools have been developed which are useful in monitoring current usage and forecasting demand. It is recommended that data is collated and reviewed on a daily basis (at least) with particular focus on CPAP, NIV and HFNO usage. This data may be difficult to source. EBME and Clinical Physics input will be useful here. Ensure that the oxygen requirements for non-pandemic patients are also assessed. Areas which can be isolated / closed during the pandemic to conserve oxygen and reduce demand should be identified.
A register should be retained of all ventilators and where they are located in the hospital. Consideration should be given to the possibility of changing operating gas from oxygen to medical air.

It is also important to note that consideration should be given to monitoring ambient oxygen levels especially in ITU areas where usage is significant. Estates would be responsible for / carry out this activity.

W-size cylinders: definition and usage


W size cylinders are the same physical dimensions as J size cylinders but are filled to 230Bar pressure. Therefore instead of providing 6,800 litres of oxygen, they provide 11,300 litres of oxygen.


These cylinders are primarily designed for use on manifolds but there have been occasions where they have been used on wards. Prior to use on wards, organisation Health and Safety / Fire safety must be consulted to provide advice e.g. securing cylinders firmly to the wall.

A cylinder regulator and trolley will need to be purchased – we host BOC advice that provides further guidance.

Further guidance

Appropriate use of medical gases is important. View our guidance page and other resources.

Materials to support safe and appropriate supply, administration, monitoring and equipment issues

Change history

  1. Medical gasses are under constant review and article series remains valid. Full content review due 2022, or sooner if National guidance dictates.
  1. Published