STERILE SERVICES Water Quality Standards for Endoscope Reprocessing
(HTM 01-06) and Washer Disinfectors (HTM 01-01) HTM 01-06
Appearance pH
Conductivity at 25˚C Total dissolved solids Total hardness Chloride Lead Iron
Phosphate Silicate mg/l
Total Organic Carbon Total Viable Count 22˚C Total Viable Count 37˚C Bacterial endotoxins Temperature
Sanitisation temperature
25mm stainless steel distribution ring mains each equipped with a UV disinfection unit, a 0.03µm absolute filter to ensure bacterial compliance and sterile sample points. The tank is fitted with a heater to allow the temperature to be increased to 85˚C for sanitisation of the tank and ring mains. The complete plant is controlled from a central control panel incorporating Vision7700 PLC with a built-in, password- protected HMI Operator Panel, comprising a 7” colour touch screen with live P&ID and alarm history that can also display historical data graphs to reflect trends.
S/cm
mg/100ml mg/l CaCO3 mg/l Cl mg/l Pb mg/l Fe
mg/l P2O5 SiO2 mg/l
cfu/100ml cfu/100ml EU/ml ˚C ˚C
Sterile services department
Southampton General is served by a central sterile services department which provides sterilisation of surgical instruments, devices and dressings for use in the operating theatres. It has seven MMM Uniclean PLII washer disinfectors, each of which uses 40 litres of water per cycle at a peak flow of 1200 l/h. The water supplied to the washer disinfectors has to comply with the latest issue of HTM 01-01 which requires a new silica standard of 0.2mg/l (see table). The new treatment plant uses essentially the same process technology as that of the
Clear, colourless 5.5 to 8.0 <40
<50 HTM 01-01
Clear, colourless 5.5 to 8.0 <30 <4
<50 <10 <10 <2
<0.2 <0.2
1 Ambient
<100 <100 <0.25 35 85
Installation was quite tricky because there was limited space in the plant room, so it was very
much a bespoke engineered solution. Glen Campbell, project manager, University Hospital Southampton NHS Foundation Trust.
JUNE 2018
Endoscopy Unit plant. However, in order to meet the new low silica standard, the duplex Osmostar units are operated in series or twin pass configuration. Each Osmostar is sized at 100% of the total design flow so that during servicing or in an emergency situation, one unit operating in single pass mode can provide the required flow of permeate. An electro polished heating coil is located in the treated water tank, this is electrically powered and can increase the temperature from ambient to 65˚C for normal operation purposes, and to 85˚C for sanitisation. As project manager Gary White observed, installation presented Lubron Water with a few challenges: “Obviously we would have liked to install the new plant where the old one was but, to keep the washer-disinfectors operational we needed suitable quality water which meant that we had to keep the old plant running while the new one was installed and commissioned.” Finding a suitable location for the new plant and distribution loop was the main problem and this caused some programme delays but Gary’s team worked with Lubron Water to plan the changeover so that there was no loss of service. In fact completion of the project was only a couple of weeks late. Commenting on the new water treatment plants, Jean Hedges said: “It’s improved the water quality no end. Because the units are twin pass, the high silica is removed to safe levels and we have had no microbiological issues. And both projects came in on budget.”
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