# How are empty cylinders changed on a manifold?

**How should staff change empty cylinders on a medical gas manifold safely?**

Under HTM 02-01 (2026), the NHS England guidance, only staff trained in medical gas safety, manual handling and cylinder changing should change manifold cylinders; its example procedure changes every cylinder in the bank, one at a time, with checks of each label and seal, slow valve opening, a leak check and a signed register.

HTM 02-01, the NHS England guidance for medical gas pipeline systems, gives in Part B (2026 edition) an example procedure that hospitals may post on the manifold room wall next to the manifold. It is headed for Medical Gas Porters (MGPS); where the guidance splits the porter role into two tiers, Tier 2 porters are responsible for receiving cylinders, moving them to and from the manifold rooms and changing the cylinders on medical gas manifolds. A permit to work is not necessary for the routine replacement of cylinders on manifolds, provided there is no danger of the supply being disrupted.

## The example procedure in HTM 02-01 (2026)

1. Prepare: clean, grease-free hands, eye and face protection, and safety footwear when large cylinders are handled.
2. Change the whole bank: when a bank needs changing, every cylinder in it should be changed.
3. Check each full cylinder: the gas name on the collar, the expiry date and the colour code. Keep valve cover caps that are hinged or have a retaining strap.
4. Follow the procedure for venting the header lines, where one applies.
5. Remove the empty cylinders one at a time and secure each in the spare rack position; never leave a cylinder unrestrained.
6. Inspect the Bodok seal in the yoke, or the O-ring on a bull nose connection, for wear or damage and change it if necessary; keep it away from grease, oil and hand cream, and use only one seal per connection.
7. Connect each full cylinder and tighten by hand or with an appropriate spanner, without straining the tailpipe and without lubricant or sealing compound. The handles on nitrous oxide tailpipes are not spanners.
8. Open each cylinder valve slowly, anticlockwise to its fullest extent, then turn it back by half a turn.
9. Check for leaks between the valve and the manifold, usually by listening, or with oxygen compatible leak-detection fluid if in doubt. If a tailpipe connection leaks, close all cylinders on that bank, disconnect, recheck the seals and reconnect.
10. Check that the contents gauges read full, and check the manifold control panel: some need a reset button pressed.
11. Move the empty cylinders to the empty cylinder store, refill the spare rack with full ones and sign the register: how many cylinders, from which bank, on which day and by whom.
12. Report a suspected fault to the estates department at once. Faulty cylinders, for example leaking or damaged ones, are not left in the manifold room: they must be labelled "faulty" and kept separate from all other cylinders, and pharmacy should be notified.

## What the manifold should allow

HTM 02-01 Part A (2026) asks for a manifold control system designed so that the cylinders of one bank can be changed without loss of continuity of the gas supply, and says there should be no maintenance or repairs on a manifold while it is in service; an alternative source of supply should be used. Cylinders for one complete bank change should be held in the manifold room, and an automatic manifold should change from duty to standby with no more than 1400 kPa left in the cylinders. See manual, semi-automatic and automatic manifolds.

## Manifold changes at a PSA oxygen plant

A Global Fund template written by Build Health International for Project BOXER, a standard operating procedure for oxygen plant operators (French version dated 9 December 2025), describes a manifold change with the manifold valve closed: close the manifold valve and the connected cylinder valves; disconnect the pigtails slowly, using clean nitrile gloves and a clean, oil-free spanner of the right size rather than an adjustable one; put protective caps on the cylinder valves; inspect the new cylinders for dust, grease and oil; connect the pigtails; open the cylinder valves slowly, one by one; then open the manifold valve. Where a valve is briefly opened to blow out debris, a common practice, the template asks for it to be opened very slowly and slightly and pointed away from everyone. The template is meant to be adapted to each plant and checked against the manufacturer's recommendations. The same project's daily checklist asks whether the manifold pigtails are in good working condition and whether a backup manifold not used in the past day is maintaining pressure.

Ultra Controlo supplies oxygen cylinder manifolds with automatic or manual switchover between primary and standby banks, and automatic control panels that switch between primary and reserve cylinder banks.

### Is a permit to work needed to change manifold cylinders?

Not for routine replacement: HTM 02-01 (2026) says permits to work are not necessary for the routine replacement of cylinders on manifolds, provided there is no danger of the supply being disrupted.

### How many spare cylinders should be in the manifold room?

HTM 02-01 (2026) asks for enough cylinders for one complete bank change; for oxygen/nitrous oxide mixtures, enough for two bank changes may be held, as the manifold room is heated whereas cylinder stores are not.

## Sources

- [HTM 02-01 (2026) Part B, paragraphs 5.99, 7.29, 9.170 and 9.171 (example manifold procedure), NHS England](https://www.england.nhs.uk/wp-content/uploads/2016/05/health-technical-memorandum-02-01-medical-gas-pipeline-systems-part-b-operational-management-aug-26.pdf)
- [HTM 02-01 (2026) Part A, paragraphs 5.24, 5.26 and 5.37, NHS England](https://www.england.nhs.uk/wp-content/uploads/2016/05/health-technical-memorandum-02-01-medical-gas-pipeline-systems-part-a-design-installation-validation-verification-aug-2026.pdf)
- [Global Fund / Build Health International (Project BOXER), SOP template for oxygen plant operators, French, 9 December 2025, sections 12.2 and 12.3](https://resources.theglobalfund.org/media/atepwfny/cr_c19rm-sop-oxygen-plant_template_fr.docx)
- [Global Fund / Build Health International (Project BOXER), PSA plant daily maintenance checklist](https://resources.theglobalfund.org/media/xbanfgrc/cr_c19rm-psa-plant-daily-maintenance_checklist_en.pdf)
- [Ultra Controlo, medical oxygen cylinder manifold](https://www.ultracontrolo.com/accessories/oxygen-manifold)
- [Ultra Controlo, automatic control panel for medical gas manifolds](https://www.ultracontrolo.com/accessories/automatic-control-panel)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/how-are-cylinders-changed-on-a-manifold/