Information on the use of W-sized cylinders and integral valve cylinders, and the implications of NIVs and HFNO on pipeline capacity.

Assessing medical gas pipeline capacity

Non-invasive Ventilators (NIV) and/or High Flow Nasal Oxygen (HFNO)

Clear clinical pathways for patients and modelling of patient needs should be developed to assess the impact of the clinical use of Non-invasive Ventilators (NIV) and/or High Flow Nasal Oxygen (HFNO) on medical gas pipeline capacity.

Areas where ventilators are to be sited and the flow rates required for patient care need to be identified. Medical Gas Pipeline Systems and Oxygen Supply Resilience has further information and 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.

Modelling usage

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 and the following considerations should be noted:

  • 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.

Ambient oxygen levels

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 and regulators: description and use


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, for which further details are provided from BOC in the attachment below. A W regulator reduces the higher pressure of W cylinders down to levels where they can be used with devices and manifolds that would typically be used with J cylinders.


In January 2023 DHSC MedTech Team has confirmed with MHRA that the quarantined W regulators already deployed to trusts or held in the national reserve, have a temporary authorisation for use until March 2023 so can be deployed immediately.

DHSC is working on a procurement to replace these regulators with fully authorised devices and will ultimately run a swap out process to ensure long term resilience.

Integral Valve Cylinders

BOC issued instructions on how to use their medical oxygen integral valve cylinders.

It is important that staff understand how to use these cylinders to reduce the risk of death and severe harm from failure to obtain and continue flow from oxygen cylinders.

Update history

  1. Updated with information about W regulators
  1. Link to Integral Valve Cylinder instructions added. Summary amended and minor formatting changes.
  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

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