Clean (pure) steam system
Pure steam generator · Clean steam generator · Pure steam distribution · Sterilising steam
The generator and distribution that supply steam clean enough to sterilise product-contact surfaces, and the tests that show its quality at the point of use.
What this page does not claim
An equipment family page teaches how a kind of equipment works and how it is assured. It is not a qualification of any site’s equipment, sets no universal limits, and was checked by SPEQ against the sources it lists, not by an independent engineer.
WHAT IT DOES
A pure steam generator boils purified feed water and delivers steam to sterilisers, SIP circuits and humidifiers. Annex 1 asks that generators be "designed, qualified and operated" so the steam meets defined chemical and endotoxin levels (6.16).
Where pure steam sterilises materials or product-contact surfaces directly, its condensate should meet the current WFI monograph of the relevant pharmacopoeia, and its physical quality should be assessed periodically against validated parameters: non-condensable gases, dryness value and superheat (Annex 1, 6.17).
Where it sits: From the utility area to autoclaves, sterilisation-in-place of vessels and lines, and other direct-contact uses.
WHERE YOU FIND IT
- Porous and hard-goods autoclave loads
- Sterilisation-in-place (SIP) of tanks, filters and transfer lines
- Humidification of clean areas where steam contacts the environment
In the reference facility: Clean utilities — WFI, clean steam & process gas, Processing & formulation suite, Equipment wash & parts preparation
Not covered on this page: Plant (utility) steam used only for indirect heating; Autoclave cycle design, covered on the autoclave page.
MAJOR COMPONENTS
- Feed water supply. Purified feed water; Annex 1 asks that it be appropriately purified (6.16).
- Generator (evaporator and separator). Boils the water and separates droplets that would carry contaminants.
- Distribution header and drop legs. Carry steam to users; sloped and trapped so condensate drains.
- Steam traps and condensate drains. Remove condensate and air that would reduce sterilising effect.
- Sampling points with condenser. Collect condensate and gases for quality testing at the point of use.
Connects to: Purified water or WFI system (feed); Autoclaves and SIP circuits; Plant steam (heating side); Building management or SCADA system.
INSTRUMENTS AND WHAT THEY MEASURE
- Conductivity sensor. Feed water and condensate quality. Watch for: compensated and uncompensated readings compared as if they were the same.
- Temperature sensor (RTD or thermocouple). Steam temperature at the header and at the point of use, for superheat assessment. Watch for: sensor not at the location that matters (cold spot, load centre).
- Steam quality test set. Non-condensable gases, dryness value and superheat at the point of use (Annex 1, 6.17). Watch for: sample taken far from the sterilizer it supplies.
PARAMETERS
SETPOINT · MEASURED · LIMIT · ATTRIBUTE- Conductivity (attribute, µS/cm). Of condensate, against the WFI monograph where steam is a direct sterilising agent (Annex 1, 6.17).
- Bacterial endotoxin (attribute, EU/mL). Of condensate, against the defined endotoxin level for the generator (Annex 1, 6.16).
- Pure steam quality (limit, % non-condensable gases or dryness value or K of superheat). Non-condensable gases, dryness and superheat at the point of use, against parameters validated for the process (Annex 1, 6.17).
- Temperature (measured, °C). At the point of use, read with pressure to show the steam is saturated rather than superheated.
SPEQ publishes no universal alarm or acceptance values: they depend on the process, the product and the site’s own qualification.
CONTROLS, ALARMS AND INTERLOCKS
- Control loop: Generator pressure and level control. Holds output pressure and evaporator level.
- Alarm: Feed water or condensate quality out of range. Warns that steam quality may be compromised.
- Procedure: Steam quality sampling schedule. Representative pure steam sampled regularly (Annex 1, 6.17).
An alarm asks for a response; an interlock stops an action; a safety function protects people and has its own risk basis.
HOW IT FAILS
- Carry-over of droplets from the generator. Contaminants and endotoxin reach the steam.
- Non-condensable gases in the steam. Air pockets in the load that steam does not reach.
- Wet steam. Wet loads and lower energy transfer.
- Superheated steam. Dry heat conditions in a cycle validated for saturated steam.
- Additives in the steam. Product or equipment contamination (Annex 1, 6.17).
ASSURANCE ACROSS THE LIFECYCLE
EXAMPLES, NOT A MANDATORY LIST- Design. Steam uses classified by risk in the CCS (Annex 1, 6.1, 6.2); Distribution drawings with slopes, traps and sampling points (Annex 1, 6.5).
- Qualification. Condensate chemistry and endotoxin; Non-condensable gases, dryness and superheat at points of use.
- Routine. Condensate sampling to the schedule; Periodic physical steam quality tests; Trend analysis (Annex 1, 6.4).
- Change. Re-testing after generator or distribution changes.
WHAT THIS DOES NOT PROVE
- Condensate that meets the WFI monograph does not prove the steam is dry, saturated and free of air. Instead: Non-condensable gas, dryness and superheat tests at the point of use.
- Quality at the generator does not prove quality at the steriliser. Instead: Samples from the point of use.
SOURCES
2 CITED- EU GMP Annex 1: Manufacture of Sterile Medicinal Products — European Commission (EudraLex Volume 4), 2022 revision, in operation 25 August 2023. EU / EEA; revised jointly with the PIC/S Committee; in force. Supports: Utility risk and records (6.1–6.6); pure steam generators (6.16); steam as a direct sterilising agent, condensate and physical quality (6.17).
- EU GMP Annex 15: Qualification and Validation — European Commission (EudraLex Volume 4), 2015. EU / EEA; in force. Supports: The qualification approach for utility systems.
HOW THIS PAGE WAS CHECKED
Researched and checked against the sources above by SPEQ (Claude) on 2026-10-21. It has not been reviewed by an independent engineer. It teaches how this kind of equipment works and is assured; it does not say any site, asset or process is qualified, validated or compliant.
- Acceptance values for non-condensable gases, dryness and superheat come from consensus standards (for example EN 285) not checked here, and are not stated.
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