The original protocol HTM22 was issued by the UK Department of Health and Social Safety in 1972 and specified that the smoke test for sodium filtration efficiency should reach 99.95%. It was updated in 1994 with HTM2022 and continued to be upgraded in 1997 and May 2006. The latest protocol document HTM02-01 for Medical Gas Piping systems covers system design and operation. It clarifies the requirements of the bactericidal filter, while increasing the filtration efficiency to 99.995%.Authoritative departments in other countries around the world also follow this regulation, including the Canadian CSA standard, Z7396.1 - 06 – Medical gas pipeline systems – Part 1: Pipelines for medical gases and vacuum, which requires the installation of sterilizing filters at the inlet of vacuum pumps.

Explanation of Sterilization Filters in UK Health Memos 9.28 to 9.31

         According to the test method of BS3928:1969, the filtration efficiency exceeds 99.995% 

         Under the condition of a vacuum degree of 630 mbar, the pressure loss does not exceed 30 mbar

         The filter has a condensation collection function and is equipped with a transparent sterilizable collection cup

         The sterilizing filter needs to be labeled with "Biohazard"

         Instructions for filter replacement and disposal are required

         AS2896 Medical Gas System describes the inlet filter as follows:

         The medical inlet filter should be a bacterial filter, with a suitable size to ensure that the pressure difference does not exceed 3.5KPa. The filter element should meet the ISO8573.1 Level 1 requirement for a filtration efficiency of 0.01 μ m

         The provisions of China GB50751-2012 Medical Gas engineering Technical Specification for sterilization filters:

          5.2.16 The filtration accuracy is 0.01-0.2μm, and the filtration efficiency is 99.995%.

          The sterilizing filter should be maintained and the filter element replaced in time to avoid excessive pressure drop affecting the system flow.