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Germ-free washing for medical instru­ments

Bonferraro’s high-tech washer-disin­fector reli­ably cleans germs off medical and labo­ra­tory instru­ments. The drying phase at the end is a crucial part of the washing program. The Italian manu­fac­turer relies on a blower that is usually used in condensing boilers.

Hospi­tals and labo­ra­to­ries are subject to strin­gent hygiene require­ments. Simply cleaning uten­sils used in oper­a­tions, such as scis­sors, tweezers, clamps, test tubes, and pipettes is not suffi­cient, because the biggest danger is invis­ible to the naked eye: bacteria, viruses, or chem­ical residues can falsify measure­ment results in labo­ra­to­ries or, in the worst case scenario, can cost human lives. With his work, Ezio Gobbi and his team helps to ensure that this does not happen. For over 30 years, the engi­neer at Smeg, since 2009 in the manu­fac­turing unit of Bonfer­raro, has been devel­oping thermal disin­fec­tors. These special washing devices ensure that uten­sils are perfectly cleaned in hospi­tals, doctor’s offices, and research facility labo­ra­to­ries.

Bonfer­raro is based in the commu­nity of the same name in the Province of Verona, Italy and is the subsidiary of house­hold appli­ance manu­fac­turer Smeg. The company has been manu­fac­turing thermal disin­fec­tors since 1987. “There are only around ten manu­fac­turers world­wide that make such devices,” says Gobbi. Most recently, the R&D team was tasked with devel­oping three types of devices with wash cham­bers ranging from 250 to 450 liters, in other words, high-perfor­mance devices that have to operate with maximum reli­a­bility. And not only when it comes to cleaning results: “If a dish­washer at home fails for a few days, it is irri­tating but not disas­trous. However, in hospi­tals or labo­ra­to­ries, work is severely disrupted,” says Gobbi. This means that the tech­nology installed must be 100 percent reli­able.

Disin­fec­tion in the high-tech dish­washer

Works like the dish­washer at home – only much more precise: the thermal disin­fector from Bonfer­raro. (Photo | Bonfer­raro S.p.A.)

A thermal disin­fector works in a similar way to a dish­washer at home. There are washing and rinsing phases, and the items are dried at the end of the program. However, there are also major differ­ences. The devices have to work with much greater preci­sion than those in the kitchen at home, and they are subject to the strict require­ments of medical prod­ucts. This even applies to the removal of coarse dirt. “If residue persists, the ster­il­izer is then unable to completely kill bacteria even at 140 degrees Celsius,” says Gobbi.

This is not so easy, as the objects to be cleaned come in a much greater variety of shapes than pots, dishes, or cutlery in the kitchen at home, for example. Every­thing gets put in there, from scis­sors and test tubes to hoses. This is why special carrying systems are required to allow the water to get every­where. The water supply and the special cleaning chem­i­cals must also be dosed in exact amounts and the temper­a­ture must be regu­lated precisely. There­fore, a thermal disin­fector has an addi­tional disin­fec­tion phase, during which it is impor­tant that the temper­a­ture is between 90 and 93 degrees Celsius exactly.

Reli­ably dry

Drying begins when disin­fec­tion is complete: the crucial phase. There must be no droplets of water left on the objects so that they can then be imme­di­ately shrink-wrapped and put into the ster­il­izer. Depending on the shape and mate­rial, this process takes between 15 and 30 minutes. “For example, plastic is much harder to dry than glass,” says Gobbi. Here too, the chore­og­raphy is finely tuned: first, air is blown into the washing chamber at low pres­sures so that the steam escapes slowly. Then hot air is supplied at different speed levels and at up to 120 degrees Celsius. “We devel­oped a drying cycle here that works as quickly and effi­ciently as possible,” says Gobbi. The blower is the crucial compo­nent for this process. It had to be espe­cially powerful for Gobbi’s three new types of devices, also because it has to cope against the resis­tance of the HEPA filters. HEPA stands for High Effi­cient Partic­u­late Air. The filters prevent germs and dust parti­cles from outside entering the washing chamber.

We devel­oped a drying cycle here that works as quickly and effi­ciently as possible.

Ezio Gobbi, Engi­neer at Bonfer­raro

So Gobbi approached ­ebm-papst: “For me, it was the logical step. We have been working together for more than 30 years on other projects.” Gobbi says the other projects involved usual house­hold dish­washers, which Bonfer­raro also manu­fac­tures. But the blower solu­tions used for these devices were insuf­fi­cient for Gobbi’s require­ments or would be too large for the avail­able instal­la­tion space at the required power. And a tailored solu­tion was out of the ques­tion: “This is not a mass market like with house­hold dish­washers. We simply do not have high enough quan­ti­ties of them: it would not pay off. We needed a product that had already been devel­oped.”

A solu­tion from the boiler

There­fore, Fabio Milani, Key Account Manager and Gobbi’s contact at ebm-papst Italy, had to look for a different way, working with the experts in Land­shut. “The power require­ments described by Gobbi were a pretty good fit for the blowers that we usually use in condensing boilers: the VGR 118 and the VGR 148,” says Milani, adding, “a partic­ular version of VGR 118 had a high-perfor­mance motor to make one blower suit­able for all three types of devices.” Thanks to EC tech­nology, the blower types enable high speeds and, as a result, high pres­sures that can over­come the HEPA filter, and all that with a compact design. They are also infi­nitely adjustable so that the speed can be precisely adapted to the different drying phases. So the perfect solu­tion? Almost, if it were not for the venturi attached to the blowers as stan­dard. In condensing boilers, it is essen­tial for regu­lating the gas supply. In Bonferraro’s thermal disin­fec­tors, it would just be disrup­tive.

Out with the stan­dard solu­tion and on to the more expen­sive customized solu­tion then? Some­thing else happened. Milani explains: “As happens by chance, the same blower was being created at the same time as vari­ants without venturi.” Gobbi bene­fited from this. He can also use it for his three types of devices. “In addi­tion to the perfor­mance char­ac­ter­is­tics, the geom­etry was a perfect fit for our require­ments,” says Gobbi. The three new thermal disin­fec­tors are under devel­op­ment and the start of produc­tion is planned in July 2022. The demand for the ­Bonfer­raro devices is growing. “The coro­n­avirus pandemic has led to a signif­i­cant increase in sensi­tivity to hygiene. And this has impacted our company,” he concludes. 

How a thermal disin­fector works: A hospital as an example

During an oper­a­tion, a surgeon uses numerous instru­ments: scalpels, scis­sors, tweezers, and many other different oper­ating uten­sils. Some are thrown away imme­di­ately after use. Others have to be cleaned, disin­fected, and ster­il­ized before they return to the oper­ating room.

01 Cleaning begins

In hospi­tals, the thermal disin­fector is located between an unclean room, from which it is loaded, and the clean­room, where the cleaned instru­ments are picked up. There­fore, it has two doors. Before loading, a specialist pre-cleans the instru­ments manu­ally.

02 The washing program

As with a normal house­hold dish­washer, it switches between washing and rinsing phases. However, the processes in a thermal disin­fector, such as supplying cleaning chem­i­cals, are controlled much more precisely.

03 Disin­fec­tion

Deminer­al­ized water is used for the washing process in the disin­fec­tion phase. Normal tap water contains too many foreign bodies, such as salts, that could remain on the objects. During disin­fec­tion, the temper­a­ture must remain constant at 90 to 93 degrees Celsius.

04 Drying

The drying process comes at the end of the program. Bonfer­raro devel­oped a finely balanced system for this process. There, the blower over­comes the HEPA filter with high pres­sure.

Depending on the selected program, the entire rinsing program takes between 25 minutes and just under two hours. From the clean­room side, the disin­fected instru­ments are removed, bagged and then put into the ster­il­izer. Only then are they ready to be used for the next oper­a­tion.

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