Application Examples

Priorclaves Cut Significantly Sterilising Costs at York University

Right across the board, in both private and public educational sectors, where there is direct responsibility for spend, financial managers are continually looking to reduce costs, reigning in capital expenditure as well as ‘cost of ownership’, the latter taking into account maintenance, servicing as well as day to day running costs.

The recent installation of a Priorclave 450 litre autoclave within the ‘plant’ research laboratory of York University’s Biology Department is certainly good news. It has strengthened its green credentials, slashing significantly energy costs associated with running a sterilisation process for compost and vegetation with a massive 90% reduction in water usage. Coupled with other benefits the priorclave has given the department a very economical sterilisation capability.

The Department of Biology is internationally renowned for the strength and quality of its research, teaching and state-of-the-art facilities, and is consistently ranked as one of the top biology departments in the country. The spacious modern teaching laboratories provide an outstanding research environment from studying cancer, immunology and tissue engineering, to novel agricultural products, environmental studies and bio-archaeology.

The ‘plant’ teaching laboratory is attended by undergraduates and those studying for a PhD, researching and tackling fundamental problems across plant biology including physiological adaptation, plant nutrition, primary and secondary metabolism, and intracellular and intercellular signaling. Within the laboratory they use a diverse approach spanning classical molecular genetics and biochemistry through to post-genomic and advanced imaging technologies. Results have contributed to a wide range of applications from improving production of the anti-malarial drug, artemisinin to increasing the yield of bioenergy crops.

Owing to the nature of the research work undertaken, this area of the University is classified as a Containment Level 1, only those with authorisation can gain access to the laboratory. In order to maintain the highest level of decontamination risk-potential, after experimental procedures involving seed and GM investigation, all waste is carefully sterilised for safe disposal using steam autoclaves.

ENERGY AND SPACE SAVING

Since installing the Priorclave SH450 in the head-house of the plant laboratory, side by side analysis of running costs with another autoclave has showed an overall saving of 56%, the major contribution to this massive saving is associated with cost of water supply and disposal, amounting to a reduction of 88% and 89% respectively. Since the University is in a hard-water area Priorclave fitted a water softener and again a very big reduction of 92% saving in salt requirements has been achieved.

The previous power-door autoclave, although only a 350 litre machine had a much larger footprint than the new priorclave and required a separately housed 45kW generator that ran constantly 24/7 to provide the required level of steam for sterilisation. By replacing this with the Priorclave autoclave it has given the laboratory more free-space within the actual laboratory as well as create a totally free room which housed the generator.

The Priorclave SH450 autoclave is a floor standing autoclave with a much smaller and integral generator which heats water on demand, this process cuts costs significantly compared with the previous autoclave design. The autoclave is called into action two to three times a day, five days a week and by heating water-on-demand it is estimated to save the University £7.58 per run. Based on this there is a potential energy cost-saving of nearly £6,000 pa.

Contributing to the efficiency of the Priorclave is inclusion of a vacuum system for Air Removal at the start of the process with an evacuation capability down to approximately 300mb absolute. During the steam generation process multiple vacuum stages can be programmed and are interspersed with heating stages to achieve faster and better steam penetration of the load. After the required sterilisation cycle Assisted Cooling is programmed to take over, rapidly reducing the pressure in the chamber, causing fluids present in the waste load to evaporate more quickly. By initiating a cooling action in solid items in particular, this process phase can be reduced to approximately 10 minutes.

The timed free steaming feature of the Priorclave with its pulsed venting for air removal contributes significantly to faster cycle times, particularly useful when sterilising problematic loads such as the heavy waste soils created by the ‘plant’ laboratory at York University, this period allows the load to be fully penetrated with steam and expel pockets of air, which inhibit the sterilisation process.

Once a chamber temperature of 112°C is reached the vent valve opens and reduces the chamber temperature to 107°C when the valve closes again. This cycle is repeated until the timed period is completed creating an enhanced level of turbulence in the chamber.

Setting programme cycles is through the simple membrane control panel which governs the functionality of the proven Tactrol microprocessor system, the autoclave supplied to York University has a five-program memory. It also features a three position setting lock key-switch preventing alteration of temperature, time and option selection settings in one position, or to allow selection of programs only or full access to all settings.

The Priorclave SH450 autoclave, despite its relatively compact exterior has a large 450 litre rectangular, steam heated chamber measuring 68 x 90x 83cm (W x D x H). It is designed for front loading, access to the chamber gained via a three-wheel door closure system, the wide opening facilitates easy loading of bulk and heavy items, via a trolley if required.

The 450 lltre autoclave is a part of an extensive range of standard floor-standing, front-loading autoclaves that offer chamber capacities up to 700 litres and if ‘standard’ does not satisfy requirements Priorclaves’ manufacturing centre in South London can bespoke design and build. The company also has a large range of smaller autoclaves starting at 40 litres, and available as benchtop or free-standing.