Hygiene validation of InteGral sink drain
December 2013 Client
Gellert Innovation ApS Report nr.
Per Væggemose Nielsen IPU Bio- og FødevareTeknologi Søltofts Plads, Bygning 221 2800 Kgs. Lyngby
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Gellert Innovation has developed an innovative drain for sinks, which supposedly is more hygienic than the traditional design, whereby it can reduce the spread of germs from hand washing. Spread of bacteria from sinks is a major concern. Growth of bacterial biofilm in sinks in the area around the drain valve and in the drains may lead to the spread of these bacteria between users and is therefore a major hygiene challenge both in the health service, food and biotech industry and in private homes.
The drain valve, however, does not meet the strict hygiene guidelines from the European Hygienic Engineering and Design Group (EHEDG) and since
There is no official test methods for assessment of drains wherefore a general method for assessing cleanability of open equipment and surfaces is therefore employed to validate weather the InteGral drain design is actually better than the traditional ones. The aim of this project is therefore to evaluate, improve and optimize the product quality and cleanability by adding the latest knowledge on hygienic design so it can live up to the EHEDG guidelines and develop methods for testing and validation of the hygienic design of the product and provide proof of concept on the design.
The evaluation was performed by IPU in the authorized EHEDG test centre that have just been established at DTU in collaboration between IPU and DTU Food Institute. This Centre holds the leading expertise in the field of hygienic design in Denmark both in the field of research, education, testing, training and dissemination.
Hygienic design, choice of materials and gaskets
Based on IPU’s knowledge of hygienic design and EHEDG guideline doc 8 a change in gasket design was proposed. Based on a sketch made by IPU, some new seals were designed by Rasmus Lage at a/s Gunnar Haagesen in close dialogue with Jimmy Gellert.
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Figure 2 New seal design
Tree different sizes of the new seal design were produced by 3D print. Test and validation of the hygienic design
In order to test and validate the hygienic design a method developed for testing open food process equipment was used. In this method a soured milk product supplemented with 0.012% (w/v) uranine AP (Merck) was used to soil the sink and drain. Then it was allowed to dry for at least 12 hours in order for it to dry out completely. Hereafter the sink was cleaned using a cleaning agent for hand wash sinks (Clean command, sanitetsrens, Virena, Hillerød, Denmark) an all purpose weak alkaline cleaner for all toilet areas including sinks (pH 11 in use solution). In the first test the cleaning agent was allowed to stay in the sink for 5 minutes before cleaning to simulate optimal conditions, while the later cleaning test were performed without the pre-soaking. The sink was cleaned using a sponge as stated in the cleaning instructions of ISS for hygiene level 4, hospitals. The sinks were first cleaned according to the cleaning instructions and the sinks and drains were examined. Then the sinks were subjected to an additional very thorough cleaning and the sinks and drains were re-examined. Finally the drains were dismantled and examined.
I order to test if bacteria could splash up from the drain and water trap the trap was filled with soured milk with uranine (0.012%, w/v) and the outlet from the water tap was placed just over the drain. The tap was opened up full for a short time a number of times and the number of splashes were recorded.
The distribution of water and the formation of splashes of water from the water tap were not investigated.
Types of valves tested
This report compares cleanability of the Integral Valve with a the original o-ring seal and the new seals, with two types of traditional valves. The traditional valves were delivered by the client no specification of the traditional valves were supplied.
Below pictures taken of the sinks and drains after first and second cleaning is displayed. First series show the two controls and the traditional Integral Vent, with an o-ring. On the next page the 3 different sizes of the new seal are compared.
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From these pictures, it is clear that Integra drain with an o-ring is much easier to clean than the traditional vents. But there are still some remains after all cleaning steps also with this vent.
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From these pictures it is clear that the Integral drain with the new designed seal is cleanable. There are very little or no remains after thorough cleaning.
Seal 1 showed no fluorescence after thorough cleaning, but there was a very little left over of the fluorescence in the sink after removing of the seal. Seal 1 did not go all the way out to the rim of the vent. The soured milk would therefore be able to go in under the outer part of the top, which would make it difficult to clean.
Seal size 2 is the best in these test no visual remains were observed after cleaning and no remains were observed after removing the sink. Here the seal goes to the rim of the vent. Seal size 3 also performed well, but did show a very small left over. Her the seal vent a bit out over the rim of the vent.
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This test was performed to test if the water from the water tap could splash up soil from the drain.
The test showed a very clear difference between the Integral Drain on the left and the control drain on the right. In repeated test runs it was not possible to generate splashes from the drain and water trap in the sink mounted with Integral vent. In the sink mounted with a control drain it was easy to generate splashes that could contain bacteria.
Integral drain mounted with the newly developed seals showed to be cleanable in the performed test. The traditional drain was not cleanable in this test.
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The top cover on Integral drain were able to hinder splashes from the drain and water trap.