As always when specifying or purchasing and expensive and complicated piece of equipment, it is essential to be able to ask the right questions and get the right answers
For many years the laboratory autoclave has been an essential item in any laboratory where microbiology work is carried out.
However, spiralling amounts of regulation over the last 25-30 years have massively changed the way they are specified, installed and used.
All of this makes buying, specifying, installing and running a laboratory autoclave more difficult than it used to be.
Gone are the days when you could look through a catalogue to pick one out and once it was delivered, plug it in with a bucket behind to catch the drips (or a pipe running into the nearest drain or through the wall) set it to 15 minutes at 121C and empty it out again once there was no pressure inside.
The addition of safety systems such as thermal or cooling locks and the increased requirement to ensure that the load is sterilised so as to meet various laboratory quality standards has extended cycle times dramatically.
This has led to the development of accessories and systems becoming available on laboratory autoclaves to assist in optimising their performance for particular load types.
Vacuum air removal, venting systems and accelerated cooling options are now more commonplace than before and as in all walks of life, microprocessor control is everywhere.
Vacuum and free-steaming systems fitted to many laboratory autoclaves to improve performance, along with increasing concern about what is carried over in the exhaust steam from autoclaves have also led to the formulation of standards and regulations requiring most of them to be connected to sealed and vented drains.
Microprocessor control systems can be a nightmare to the technophobes among us so it is important to consider who is likely to be using the equipment and how often the settings may need to be changed.
Some systems are as easy to set up as the timer and temperature gauges on 'older' autoclaves, whereas others require a manual and passwords to make even a small adjustment to the set time or temperature.
As always when specifying or purchasing and expensive and complicated piece of equipment it is essential to be able to ask the right questions and get the right answers.
It is important to think about what you are going to put into the autoclave to make sure that the autoclave that you buy has the right specification to process it effectively and efficiently, especially if you are going to have to prove this to a certifying body later on.
A good start might be to visit the products area on this site.
After you have selected one of the models it has a unique additional feature allowing you to select your load type(s) and the type of laboratory that you work in.
It will then generate a list of recommended and suggested options to suit your proposed use.
You can continue with the process to get a priced quotation from Priorclave but armed with this information you will know what you require and which questions to ask from any other supplier.
Typical questions to assess what type of autoclave is most suitable might be:.
1 - Top or Front Loading? A Top Loader has a smaller 'footprint' and accommodates taller items but loading/unloading can be more difficult.A Front Loader is easier to load, has better steam circulation and more difficult to overfill but has less useable space for a given volume.
2 - Electrically or Steam Heated? Electrical heating by a separate steam generator inside the autoclave body has fast heat up/cooling times but is more complex and therefore more difficult to fit and maintain.
Electrical heating by heaters inside the chamber the system is easy to maintain and service but cooling will be slower unless the water charge can be emptied.
Steam heating has the fastest heat up/cooling times but a reliable supply of dry steam is required.
There will be additional costs for installing steam reducing and condensate return sets.
Condition and possible chemical contamination of the steam should also be considered with autoclave loads that are for re-use.
3 - Cylindrical or Rectangular Chamber? Round Chamber: As the pressure inside the chamber will naturally try to make the chamber round the chambers can have thinner walls, making them lighter and less costly.
They have better steam circulation and are more difficult to overfill although have less useable space for a given volume.
Rectangular Chamber: For a given footprint there is more capacity with less wasted space but it is easier to overfill.
Also they are more expensive since thicker walls and external bracing is required to hold their shape under pressure.
4 - Manual or Power Door? Manual Doors are less complex, require less servicing, are less expensive but the trade-off is the space required for opening.
Also they are more difficult to open than the push-button alternative.
Power Doors, with vertical or horizontal opening, have a simple push button operation with no 'door swing' but still need space for door at rest to the side or underneath the chamber.
Many types rely on moving door seals, which can require frequent changing and the complexity of a power door makes them more expensive, requiring regular maintenance.
Once the general model type is established there remain further questions.
5 - What will be sterilised; bottled liquids, glassware, laboratory equipment, porous loads, waste? Generally all autoclaves are capable of sterilising all types of loads but in order to get the best from your considerable investment it is worth investigating what options might be available to efficiently process the type of work you are doing.
A waste load can processed far more effectively by using options such as vacuum and free steaming but using these on a media load could lead to disaster.
Some laboratories use a different autoclave for each load type to avoid cross contamination, but for smaller laboratories this can easily be overcome by having pre-set selectable programs for each load type.
Once programmed and 'locked off' these cycles can also be qualified.
6 - How much Space is required and what Services are Required? You must also consider where and how the autoclave is to be installed.
Will there be enough space around it for service access; does the proposed drain have a vent; will the drainpipes and joints stand the temperature of the exhaust from the autoclave and finally can you get the autoclave into the suggested location via any stairs corridors, tight corners and doors.
Any reputable supplier will be able to provide assistance, advice and information on these factors.
Often you will be able to arrange a site survey to make sure that everything is going to fit.
7 - How do you prove sterilisation? Today more than ever emphasis is being put on the ability to show that an autoclave is being used properly and is correctly set up.
An autoclave should have the option of a data print-out to prove a cycle has been completed and required parameters met.
Many can also transfer information securely to a computer for storage and analysis.
At minimum, a thermocouple entry port should be available to allow a remote chart recorder to be used.
A second cable entry port should also be available to facilitate testing and calibration of the autoclave for external monitoring and approval schemes.
Most manufacturers take account of these factors in their designs and many are expert in testing, and can give valuable advice and offer additional features to optimise autoclave performance.
Finally, once your autoclave is delivered it is easy to forget that it is there, until that is it breaks down and the work starts to build up.
On-going maintenance and service should be considered as part of the purchasing process, after all you wouldn't buy a new car and expect it to run forever without servicing.
Make sure that you don't save a few pounds on the initial purchase and end up with years of down time afterwards.
Find out whether preventative maintenance is available and what is covered by different supplier's preventative maintenance packages and warranties.
At the end of the day you must decide for yourself what you will buy.
Of course price is an important factor in this but bear in mind that having and providing good knowledge and backup to ensure trouble free installation and operation costs money but can very soon turn out to be a wise investment.
