HTM 2030

6.24 Cleaning efficacy test are intended to demonstrate the ability of the WD to remove or reduce to acceptable levels, soiling and contamination which occurs during normal use of re-usable items.

6.25 Naturally occurring contamination shows considerable variation both in the nature and proportion of constituents and also in the extent of soiling which may occur during use.

6.29 Artificial test soils are designed to simulate the nature of native soiling and to be equally, or more difficult to remove.

6.30 By incorporating appropriate marker substance, they can provide improved sensitivity detection.

6.31 Test soils can be used to give a quantified loading level, quantified detection and hence a quantified estimate of the soil removal which has occurred.

6.33 Woldwide, many different test soils have been specified for testing WDs but they generally fail to meet the key criteria necessary for a test soil. These criteria include:

• a chemically defined formulation (the traditional soils use substances such as flour, wall paper paste, fresh egg yolk, horse blood, etc which introduce a significant variability);
• a quantitative method of applying the test soil to the surfaces of all types of item to be processed;
• a quantitative method of detection of soiling remaining after the washer-disinfection process;
• validated with a known relationship to native soiling for ease of removal, relevant residual levels, etc;
• safe to handle, easy and economical to use.

10.1 Cleaning efficacy tests are used to demonstrate the ability of the WD to remove or reduce to acceptable levels, soiling and contamination which occurs during normal use of re-usable items. Test soils are used to simulate naturally occurring contamination since the latter show considerable variation and is therefore more difficult to use for standardised testing.

10.4 The manufacturer should establish 'worst case' conditions of temperature, detergent concentration and water pressure/flow rate for use during testing.

10.9 The choice of test soil to be used should be based on the intended use of the WD and should be formulated to simulate the soiling which will be encountered in practice and which would be most difficult to remove.

10.12 These performance criteria include the following.

1. The test soil formulation should be validated as being of equal or greater difficulty to remove than the naturally occurring soils which it is intended to simulate.
2. The method of application to give a level of soiling which is reproducible within specified limits should be validated and documented.
3. The method of detection of residual soil should be quantititative, visual assessment along should not be regarded as satisfactory.
4. The limit of sensitivity of detection method employed should be established and stated.
5. For tests on the chamber walls and load carrier, the detection method shall include a validated method for quantitative detection of the residual soil in situ or a validated method of removal eg by swabbing for subsequent evaluation.