Small but Powerful - Operating Fluid Free Central Vacuum Supply in New Clinic

The VCR centre for spinal injuries in Viborg, Denmark commenced operations in March 2014. The new centre has 34 beds, and provides care for patients recuperating after spinal injuries. The modern clinic has a central vacuum supply powered by dry-running Mink claw vacuum pumps.
The VCR centre for spinal injuries in Viborg, Denmark has been treating patients since 2014
The VCR centre for spinal injuries in Viborg, Denmark has been treating patients since 2014

VCR Viborg is run as an independent centre for patients with spinal injuries, but is a part of the neurology department of Viborg regional hospital. When the clinic was built in 2014, the management opted for a Busch central vacuum supply. Viborg regional hospital and other clinics administered by the regional authority of central Jutland (Region MIDT) also rely on similar Busch vacuum systems.

The central vacuum supply comprises a rack of three Mink MV 0040 B claw vacuum pumps, an upstream 500 litre vacuum reservoir, bacteria filters and a controller. The system is installed in a utility room in the basement, and supplies vacuum to 40 connections in patient rooms, treatment areas and operating theatres throughout the hospital. As the hospital is relatively small, Busch offered VCR Viborg a vacuum system equipped with three of the smallest Mink claw vacuum pumps, each with a pumping speed of 40 m³/h. Two of the three Mink MV vacuum pumps maintain a vacuum level of about 250 mbar in the vacuum reservoir. If devices requiring vacuum are connected anywhere in the hospital network, air flows into the vacuum reservoir. The subsequent rise in pressure causes one of the two vacuum pumps to start automatically, returning the vacuum level to the desired value. All three Mink MV vacuum pumps have an integrated frequency converter, and are controlled to deliver the minimum output required to maintain 250 mbar in the reservoir. This means the vacuum pumps often run at reduced speed, allowing them to operate extremely efficiently.

The second vacuum pump is activated only when the output of the first is insufficient. The system is dimensioned so this occurs only in extreme cases. The controller starts the vacuum pumps alternately, so the number of operating hours for each unit is approximately equal.

The third Mink MV 0040 B serves as a standby and reserve unit, and is controlled redundantly by a pressure sensor in the reservoir. If this sensor detects a sudden rise in reservoir pressure – only possible if the system has a leak, or the other vacuum pumps have stopped – the standby unit is activated. The hospital vacuum supply is thus guaranteed, even if two vacuum pumps fail. The standby unit can also be used when maintenance work is carried out on the other two vacuum pumps. In this way the system is designed in accordance with the European standard EN ISO 7396-1 'Medical gas pipeline systems - Part 1: Pipeline systems for compressed medical gases and vacuum'.



The VCR Viborg central vacuum supply with three Busch Mink MV claw vacuum pumps

Mink claw vacuum pumps offer the advantage of dry compression. In contrast to the oil-lubricated vacuum pumps often used in the past, no operating fluids are required in the compression chamber. This makes contact-free claw technology possible: none of the moving parts touch each other, so lubrication and cooling are not required and no component wear takes place. For the operators of Mink vacuum systems, this means almost no maintenance – oil, filters and components do not need replacement. Mink MV servicing is restricted to a gearbox oil change every 8000 operating hours. Due to the way operating hours accumulate in the VCR Viborg system, this corresponds to a theoretical service interval of several years. However, the two bacteria filters installed between the reservoir and the vacuum pumps require regular inspection. These filters prevent bacterial contamination from the vacuum pumps to the hospital environment. The filters are arranged in parallel, with only one filter in use at a time. A shut-off valve diverts the air flow to the other filter to permit cleaning or replacement without interrupting the vacuum supply.

After more than a year of operation, the technical staff at VCR Viborg are extremely satisfied with the central vacuum supply. Maintenance has not been an issue, as the system has performed perfectly and the first service is not due for some time. Also reassuring is the local support by Busch Denmark, with advice and practical assistance from vacuum specialists available at any time.


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