EFHSS Questions and Answers - Question Q00249

Dear Sir/Madam,

My Question:

1. What should be the water Hardness in terms of German Degrees for the use in Washer Disinfectors according to HTM-2030 and
2. what should be the level of Chloride ions allowed in the water that is used in the Washer Disinfector?

Please determine what type of test should be carried out to check the levels of hardness and chloride ions present in the water.

Regards,
Norberto Agnelo
Kuwait

Dear Noberto,

There is often confusion in the terminology used to denote hardness in water Degrees Clark, grains/Litre, ppm calcium salts. [to name but three]. Our website, over the next week or so, will try to help clarify this and give a formula for interpretation of such terminology (see: www.processtech.co.uk).
We will outline also the best way to interpret the testing requirements under 2030 for rinse water as well as give practical advice on the areas of infection concern associated with certain systems. Sanitising water softening systems [and other treatments] is very important, but it must be carried out so as not to damage equipment.

Kind regards
JIM DALY M.D. for Medipure Ltd

Dear Norberto,

Water for final rinse in washer disinfectors should be deionised to prevent spots and deposits. Water for pre-wash, main wash and intermediate rinse should be softened to optimize cleaning strength and to prevent deposits in chambers of washer disinfectors. We do not recommend water with hardness as feeding water for washer disinfectors but if no water treatment is possible the waterhardness should not exceed 5 °d German total hardness for pre-wash, main-wash and intermediate rinse.

Chlorides can lead to pitting corrosion.Final-rinse water should be free of any chlorides because this water dries up after final rinse and dissolved salts are concentrated on the surface of goods to be washed. Deionised water is free of chlorides.
Other water, which is used for pre-wash, main wash and intermediate rinse, should have less than 100 ppm of chlorides to prevent corrosion.

Dr. Jürgen Staffeldt
Chemische Fabrik DR. WEIGERT GmbH & Co. KG
Anwendungstechnik neodisher
Mühlenhagen 85
D-20539 Hamburg
Tel. (49) 40 / 789 60 - 165
Fax (49) 40 / 789 60 - 123