# What should be done when fluid gets into the vacuum pipeline?

**What should be done when patient fluids have been sucked into the medical vacuum pipeline, and how is it prevented?**

HTM 02-01 Part B (2026), the NHS England guidance, says any contamination of the medical vacuum pipeline should be reported immediately to the Authorised Person (MGPS), with the infection prevention and control team also advised, and the section decontaminated with a detergent or disinfectant solution drawn or pumped through the terminal units, then rinsed.

## How fluid gets in

HTM 02-01 Part B (2026 edition) describes the protection at the bedside: suction controllers are fitted with integral filters and floats to keep aspirated fluids out of the pipework, fluid drainage jars are fitted with floats and are often used with an anti-foaming agent, and the tubing from jar to controller is often protected by a hydrophobic filter that seals the tube if the filter becomes wet (11.214, 11.215). Contamination of the distribution system may result if one or more of these features is omitted or compromised, and repetitive induction of fluids can block the pipeline as transported and dissolved solids dry out (11.216, 11.217). Part A asks for suction control devices with a slam-shut mechanism and a hydrophobic filter (4.108) and does not permit wet vacuum systems, in which fluids are drawn through a fixed pipeline to a remote suction jar (3.11).

## First steps

- Notify the Authorised Person (MGPS) immediately; medical staff should be aware of this responsibility, and the IPC team should also be advised (11.218).
- The Authorised Person (MGPS) raises a permit to work to take other downstream terminal units out of service if possible.
- Establish with the surgical or clinical practitioners the possible nature and volume of the contaminant, and consult the IPC team on the level of microbiological hazard, including the pathogenicity and persistence of any infectious agents.
- Use the as-fitted drawings to identify downstream terminal units that may be flooded during cleaning.

## Two cleaning methods

Previous decontamination procedures recommended circulating the cleaning fluid towards the central plant using the system vacuum. Where it is possible to circulate the fluid with a pump through the terminal units and a local AVSU NIST connector, Part B prefers that method, as it limits contamination to the local pipework; this is particularly important in older systems with terminal unit drops from beneath the distribution pipework rather than the up-and-over arrangement the HTM prescribes (11.220).

- Using the system vacuum: prepare a 1% solution of one of two proprietary products named in the HTM, plus sodium dichloroisocyanurate, in about 10 L of hot water; aspirate 1 L through the terminal unit immediately upstream of the contaminated one, 5 L through the contaminated terminal unit and 0.5 L through each of the next ten terminal units, or as specified, keeping a low flow through a suction controller; check downstream terminal units for solution and repeat where it is found; then repeat the whole procedure with clean hot water.
- Using a fluid pump: with the local AVSU isolated, feed the disinfectant solution through the AVSU's upstream NIST connector and out of the contaminated terminal unit, fitted with an open probe and disposal hose (11.222); flush any downstream terminal units where solution appears, repeat with clean hot water and make sure the pump removes as much water as possible.

Both procedures end by taking the system back into use, checking the plant filters for fluid and changing the bacteria filters where fluid is present, and monitoring the system for a few days, with vacuum control units fitted, for evidence of liquid. Where a blockage completely restricts the pipework, the risks of using high-pressure fluid pumps must be weighed against the disruption of removing and replacing the pipework (11.221).

## ULTRAVAC

The ULTRAVAC basic configuration includes 2 bacterial filters with liquid separator: a transparent liquid separator or drain flask collects liquids and impurities to protect the bacterial filter element, and the filters have vacuum differential gauges and isolating valves.

### Who must be told about fluid in the vacuum pipeline?

The Authorised Person (MGPS), immediately, and the infection prevention and control team, as HTM 02-01 Part B (2026) asks for any contamination incident.

### Can fluid block the vacuum pipeline?

Yes. HTM 02-01 Part B (2026) says repetitive induction of fluids can block the pipeline as transported and dissolved solids dry out.

## Sources

- [NHS England, HTM 02-01 (2026 edition) Part B, paras 11.214 to 11.222 and procedures for vacuum system decontamination](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)
- [NHS England, HTM 02-01 (2026 edition) Part A, paras 3.11 and 4.108](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)
- [ULTRAVAC datasheet, pp. 2 and 3](https://www.ultracontrolo.com/products/ultravac)

Reviewed: 2026-10-23. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/what-to-do-when-fluid-enters-the-medical-vacuum-pipeline/