Pure steam Quality test

In the pharmaceutical manufacturing and healthcare industries, there are basically two types of steam--process steam and pure steam. Process steam is also known as plant steam, black steam, utility steam, boiler steam etc. Pure steam is sometimes known as clean steam.

Process steam is defined as a general purpose steam whose quality is not been optimized for sterilization. Where it is not intended to be in direct contact with medical devices, medicinal or culinary products, no specific physical,

Typically, in these processes, pure steam is injected into equipment or piping to create a sterile environment, or into autoclaves where loose equipment, components (such as vials and ampoules), or products are sterilized. Pure steam may be used

Physical properties required for pure steam

Tests Acceptance Criteria
Non Condensable gases 3.5 percent (max)
Dryness Value 0.9 percent (min)
Super Heat Value 250 C (max)

for some other functions where conventional utility steam might cause contamination, such as humidification in some clean rooms, and injection into high purity water for heating prior to Clean-in-place (CIP) operations.

Concept of pure steam quality testing

Until Health Technical Memorandum 2010 (HTM 2010) was published, there had been no requirement for routine physical steam quality testing within National Health Services (NHS). The pure steam was tested only for chemical and biological specifications. While HTM 10 (4) provides details of dryness value and non condensable gas tests, these were to be employed as circumstances demanded. Prior to this, testing had been restricted to the subjective assessment of load dryness and the measurement of superheat as part of routine thermometric testing.

In the mid of 1970 the British NHS was incurring significant costs as the result of failed porous load/equipment sterilization cycles. Failures were principally due to wet loads, the failure of chemical indicators on packaging and in the Bowie Dick test to properly change colour and air detectors causing cycles to automatically fail. In addition to the evident quality issues, this resulted in loads having to be re-packaged and re-sterilized at considerable expense.

Poor quality of pure steam and pure steam distribution pipe line designing, steam trap functioning of steriliser results in failure of heat distribution.

It has been seen that wet steam, superheated steam or non-condensable gases all have the potential to adversely affect the sterilization of equipment loads in the pharma industry. The extent of which the process is affected will be dependent on the extent of the problem and the nature of the load. Good practice indicates that we should be aware of the condition of the steam we use for sterilization of equipment or porous loads, to both confirm that the design requirements of our steam raising plant have been satisfied and to assist with troubleshooting. While routine testing at an annual frequency at the point of use is indicated by HTM 2010, the period between tests may be inadequate to detect any transient or seasonal problems that exist.

Now, as a Good Manufacturing Practice (GMP), International Organization for Standardization (ISO), HTM 2010, EN 285 has defined the quality of steam used for sterilization purpose. It is necessary to ensure and validate the quality of steam on regular basis.

Steam quality testing has been a requirement within the European Union (EU) for many years by EN 285 and is being adopted by many other countries and the pharma environment across the world.

To ascertain the quantity of non condensable gases from the pure steam, it is necessary to have non condensable gas removal (NCGR) arrangement prior to pure steam generator.

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