Priorclave manufacture everything at their London facility, and unlike many manufacturers, produce all their own pressure vessels in-house.

Thirty people at the factory, which is a debt-free family-owned small business with approximately £3M in annual revenue.

More than 30 years, since 1988

Overheat Protection (fault code F003) is a standard feature on all Priorclave models with Tactrol control systems.

This functions from the main autoclave controller and takes its temperature feed from the autoclave temperature control probe. If the control system detects a temperature above 142C then the program is aborted and the F003 overheat error code is displayed.

In addition to this there are other safety systems fitted:

Firstly, in the case of the heater not being under control the safety valve will prevent the autoclave going above the design pressure of the pressure vessel. This will vent and close around 2.4 Bar rather than blowing down all the steam in the autoclave. This is to give a measure of protection against any biological hazards which may be present within the autoclave load. If left unattended and not manually switched off the water in the autoclave will be used up by the heater and the low water system will shut the autoclave off.

In the event of a failure of the safety valve and low water system the F003 would be the next point at which over-temperature /pressure would stop the autoclave.

Finally in the event of a failure of all these systems then the heaters are fitted with a non-resettable cut outs in their individual electrical power feeds which will cut off the power to the heaters if their trigger temperature is reached.

The pressure vessel is rated up to 2.5 BarG, but the safety valve is set for 2.4 BarG (138°C) to conform with PED regulations.

Overheat Protection (fault code F003) is a standard feature on all Priorclave models: The Tactrol control system monitors the autoclave temperature control probe. If it exceeds 142ºC (roughly 280ºF) then the program is aborted and the F003 overheat error code is displayed.

Some facilities may be concerned about the impact their autoclave has on the building HVAC system.  Although the heat output from the autoclave is cyclic and varies throughout the cycle, a good rule of thumb for the thermal load placed on the HVAC by the autoclave is that it will be equal to roughly one third of the total heater power of that model per cycle.  (Engineers at our London factory have compiled this Power Ratings and Heat Dissipation Table. If the autoclave is steam heated from an external supply, you can use the heater power of the corresponding electrically heated model as a basis for estimating the thermal load.)

Models with internal steam generators (although heavily insulated) will give off a little more heat, since the generator runs throughout the cycle and even when the autoclave is not in use. Models with a steam jacket will give off a little less heat, because the jacket is insulated, and if water cooling is used the heat is ideally shunted out the drain.

Although it is impossible to say how much water an autoclave will use without knowing a great deal about your operation, we can offer a rough guideline.  As a rule, benchtop models with condensate bottle exhaust will consume as little as ½ liter per cycle.  Models with drain condenser exhaust cooling will consume 15—25 gallons per cycle.

In the interest of accuracy, we gathered the following data by monitoring water consumption on an autoclave with a fairly popular laboratory configuration (a 150L Priorclave front-loader with a vacuum system and drain condenser) running standard sterilisation cycles:

Autoclave Use: On average for a normal cycle, around 3.3L is lost as vented steam from the autoclave chamber.  This is replenished by the water fill system at the end of the cycle. (The chamber holds around 12L.)

Vacuum Pump Use: This varies widely by cycle type, but on a cycle with the standard two pre-heating vacuum pulldowns and 12 post-cycle vacuum pulldowns, around 35L of water is used per cycle. If only a pre-heating vacuum is used, then the water consumption drops to around 10L per cycle.

Exhaust Cooling Condenser Use: This also varies by cycle (the condenser is thermostatically operated, and this only runs as needed).  On a cycle with the standard two preheating vacuum pull-downs and 12 post cycle vacuum pulldowns, the drain condenser consumes around 10L per cycle.

Our pass-through sterilisers are designed for air-tight fitting through separating walls, allowing for decontamination of material prior to release from the facility. They are also fitted with interlocking doors such that the outer door cannot be opened unless the autoclave has completed a decontamination cycle.

In order to meet effluent retention requirements, our pass-through units can be fitted with an exhaust filtration system that captures all hazardous pathogens: All autoclave exhaust is passed through a 0.05 micron microbiological filter mounted outside the autoclave chamber. Once the door is shut and the cycle is started, unsterilised effluent is returned to the autoclave chamber for sterilising on the next run.

In our Electrically Heated Models steam is generated in the chamber itself. This provides for enhanced steam circulation, excellent water conservation, and reduced service costs by reducing the number of moving parts by a third.

The vessel can be drained at the end of each cycle and refilled, or the water can be reused, depending upon your specification.

Our Steam Heated Models can also have the option of an internal “on demand” steam generator, mounted within the body of the autoclave.

Both perform the same function of sterilisation by steam but are designed and built to be used in different ways.

Generally Medical grade autoclaves are designed and built to process large volumes of items to pre-set cycles almost continuously. Consequently they are often large and fitted with steam jackets and steam generators and use large amounts of energy and water for their operation, which is justified by their need to operate constantly.

Research Grade Laboratory autoclaves in contrast are designed to operate over a variety of cycle types, temperatures and pressures to meet the specific needs of research laboratories.

Their sizes are more suited to the space available in most laboratories and they only use energy and water when they are running. They are generally less complex than Medical Sterilisers and require far less maintenance.

Priorclave autoclaves use water in two ways, to produce steam for sterilising with electrical heaters inside the autoclave chamber and for ancillary equipment such as vacuum pumps and cooling condensers.

Mains / tap water can be used directly for the ancillary equipment as the volume and water pressures required (a minimum of 2 Bar) make the use of or need for treated water an unnecessary and impractical expense.

Where the autoclave is heated by external steam then specific feed water requirements will be covered in the manual for the steam boiler.

WATER QUALITY
To avoid unnecessary and costly maintenance and in some cases possible contamination of autoclave loads, close attention should be paid to the quality and condition of the water used to generate steam in electrically heated models.

In these models heaters are fitted to the bottom of the autoclave chamber and sit in a reservoir of water from which the sterilising steam is generated.

The major cause of maintenance issues with Laboratory Research Grade Autoclaves is water hardness and particularly hardness due to calcium carbonate. Over a relatively short period of time limescale from hard water will start to coat the heaters, initially reducing their effectiveness and ultimately causing them to fail.

Lime-scale build up will also affect the operation of water level sensors and the efficient operation of valves.

A less common issue is water supplies containing a high level of particulates, which can also affect the operation of valves. This can often be an issue in new buildings for a short period while newly installed pipes flush through.

Unless the water supply is defined as drinkable (potable), soft water (in the UK soft water is defined as having a total hardness in terms of Calcium Carbonate of up to 50 mg/L or 50 ppm) then water treatment is strongly recommended.

Although in many laboratories distilled and ultra-pure water supplies are often abundantly available these are unsuitable for Priorclave Laboratory Research Grade Autoclaves unless the autoclave has been specially adapted to run from these types of water supply.

There are two main reasons for this; the first is that extremely pure water prematurely corrodes the copper pipework and brass valves and fittings used in the autoclave and the second is that heater protection and water level controls use the conductivity of the water in the chamber to detect it.

Priorclave recommend the use of a sodium ion exchange water softener, which removes Calcium Carbonate, reducing limescale formation, while keeping conductivity levels at a detectable level.

Although electrical and magnetic softeners are available which operate by changing the nature of the calcium carbonate so that it is less able to form lime-scale, these are not recommended as over a short period of time the denatured calcium carbonate becomes concentrated within the autoclave and forms a thick white powder in the bottom of the chamber.

If you already have a water supply that you feel may be suitable the key figures for suitability are as follows:

• Total hardness in terms of CaCo3: < 50 mg/L (50ppm)
• Conductivity: > 100 microSiemens

Investing in proper water treatment goes a long way towards trouble free operation but this not a substitute for a proper cleaning, draining and flushing regime.

The pressure vessel is rated up to 2.5 BarG, but the safety valve is set for 2.4 BarG (138°C) to conform with PED regulations.

There are many factors that affect the temperature of the discharge steam/water. With no drain condenser fitted, the autoclave will be purging steam up to 121°C. All discharge will be through the vent outlet pipework. The autoclave can drain its water if drying options are fitted—this will drain the chamber after process countdown, with temperatures as high as 136°C.

With an exhaust cooling condenser fitted, the water temperature will be approximately between 40°C and 60°C. Please note that water can be drained through the manual drain at any temperature.

Soft water is the most reliable, and least expensive, source for sterilisation. Purified water is best suited for specialty applications like medical device or GMP production. Because it is highly corrosive, purified water requires stainless steel pipework, which is quite costly, and even then presents additional challenges for proper maintenance. Research-grade autoclaves can be configured to use either common soft water, or purified water.

Because Priorclave autoclaves use water conductivity to detect the water level in the chamber and protect the heaters the use of deionised (DI), pure, or distilled water is NOT advised. Additionally ultra-pure water has a corrosive effect on the copper pipework and brass fittings used in the autoclave. We recommend the use of a softened water supply to protect the autoclave heaters from the effects of lime scale.

For more information about water quality, check out our paper Priorclave Water Quality Requirements.pdf.

In order to achieve proper sterilisation, air has to be removed from the chamber.

Non-vacuum or “Gravity” autoclaves allow the steam to displace air through a port in the chamber as the autoclave heats up and by venting at slightly elevated pressures – a process known as “Freesteaming”. This process is sufficient for air removal from lighter waste loads in circular autoclave chambers which are difficult to overload.

Vacuum autoclaves use a vacuum pump to actively remove the air from the chamber. This is especially useful with waste loads in rectangular autoclaves and for hollow items. The vacuum pump can also be used to speed the cooling of waste loads and if drying is required vacuum is essential.

Research-grade autoclaves can be configured for either. Gravity/Freesteam and Vacuum stages are not used together. So long as you purchase the vacuum options, the autoclave is capable of both pre-vac and freesteaming/gravity cycles. You can adjust how you want cycles to run—simply turn off the vacuum pump option to run a freesteaming/gravity cycle.

We can connect to a sink drain so long as it is vented properly (in accordance with plumbing codes) and not too high above the finished floor (relative to the autoclave chamber drain).

An extractor hood will help reduce steam and heat build-up in the room, and help to reduce odors—particularly if the unit is placed in a small room, or run on a regular basis. If disposable plasticware is being processed, then an extractor hood should be considered, especially if there is a risk of potentially harmful fumes.

That said, please bear in mind that the air handling systems of modern laboratories are quite sophisticated. We recommend consulting with a qualified engineer before making any decisions that may affect building HVAC systems. If necessary, research-grade autoclaves can interface to building systems to provide proper on-demand ventilation.

You’d think that we could furnish a chart of typical cycle times based on load type, right? But autoclave companies cannot recommend generic cycle lengths or temperatures, even if we know the density and composition of the load.

Not only do many parameters differ by application, but regulations can also play a role in what constitutes an appropriate processing time. Likewise, many universities create guidelines for their own labs.

We can tell you that we see many labs running cycles between 15 minutes and 90 minutes. We also see liquid loads that can take several hours to complete (with natural cooling).

Our control system can be set to run cycles of any duration, from 1 minute to 999 hours. Cool-down times are directly related to the mass and density of the load. There are a number of options we can build into the unit to accelerate or control the rate of cooling, as necessary.

As a research-grade product, there are no standard programs. Custom programs can be set—and changed—at any time.

Our technical support staff is happy to guide you through the process, if needed.

Any of our autoclaves can be equipped with an air ballast to permit autoclaving of sealed cans or pouches. Many of our food and beverage customers use our autoclaves in this way, but some choose a retort machine (which we do not manufacture) depending on their throughput.

Yes—we can configure preset selectable programs for each of your load types.

Vacuum functions provide 3 features:

1. Removal of air more effectively from difficult loads (evacuates the chamber during pre-cycle stages)
2. Accelerates post-cycle stages (pulling the steam out of the chamber to accelerate cooling)
3. Dries loads (multiple pulses applied in succession can dry glassware, tips, instruments, etc.)

Vacuum functions are not suitable, or necessary, for all types of loads. There is no reason to pay for them if you don’t need them. In fact, if your autoclave is equipped with a vacuum and it goes unused, it could present maintenance issues.

Research-grade autoclaves can create a natural vacuum as they drain without the use of a vacuum pump – effective for many applications. For example, glassware comes out mostly dry, although a box of tips would require additional drying, which can be provided by a drying oven.

You might consider vacuum options if you run more than five cycles per day on a regular basis, or if you run porous loads (textiles and wrapped instruments) that must come out fully dry.

Automatic timed freesteaming is a form of gravity displacement.  Initiating at a preset temperature and continuing for a predetermined period, freesteaming allows sterile steam to push the air out of the chamber. This results in more reliable sterilisation of a wider range of loads.

Since our pass-through autoclave customers work in a variety of fields—ranging from agricultural research to product development and pathogen containment—it would be difficult to identify a single standard to focus on. What is most important is that an appropriate certification is established, validated, and adhered to.

We encourage the certification of all pass-through autoclaves “as-installed.” Every discipline of science has their own standard (helium, halogen, smoke, etc.). Depending upon the application and environment, we also encourage re-certification on an annual (or more frequent) basis.

A range of rectangular chambered models are available with Vertical Power Doors

Electrically heated and steam heated autoclaves both use steam and pressure to sterilise loads. The difference is that electrically heated models generate their own steam within the chamber, whereas steam heated models can be connected to a “house” or other external steam source.

We typically recommend electrically heated over steam heated models. Not only are they more reliable and cost effective for research applications, they’re also easier to install and maintain.

Steam Heated models require an external steam source such as steam from an on-site boiler house or sometimes a steam generator built into the autoclave – separate from the main autoclave pressure vessel. On these models steam is injected into the autoclave to heat and pressurise the autoclave and its contents. Although these direct steam heated models can give a slightly quicker cycle time by up to around 10% they do have disadvantages in terms of initial and ongoing expense:

• you need a steam supply available and to have installed or purchase all the regulation equipment required to provide steam at the correct pressure and condition (dry and saturated), or you have to purchase a steam generator.
• if the “house” steam supply is down for maintenance so is the autoclave.
  built in steam generators add complexity to the autoclave and therefore require more maintenance and possibly will experience more downtime.
• generally they use more energy due to either the heat losses in transmitting the steam from a central boiler or because internal steam generators are running all of the time even when there is no demand for steam (over 50% of a normal operating cycle and all the time the autoclave is not in use).

Electrically Heated models use electric heaters fitted inside the autoclave pressure vessel to generate steam inside the vessel. These heaters are only running and using electricity during the heat-up and sterilising parts of the cycle.

For further information can I refer you to page 17 of our Autoclave Knowledge Bank booklet, which runs through all the different variations of heating systems, vessel types and vacuum systems and other general information to assist in the correct specification of a laboratory, research grade autoclave.

Our research-grade products are capable of running all the same cycles as the more complicated medical-grade units.  Since each steriliser shipped is built to order, we omit options you do not require. This increases the reliability of the unit while reducing both the initial purchase price and the total lifetime cost of maintenance and operation.

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 is more difficult to overfill, but has less usable space for a given volume.

First, take a look at our Guide to Autoclave Installation.  This document offers a solid foundation in autoclave installation.  Depending on your circumstances, what is being autoclaved, how often, and other factors, you may determine you need some guidance in finding the right solution for you. For more detailed assistance, please contact Technical Support directly.

For new installations in the UK we can often arrange for one of our Service Technicians to come and look at your proposed installation site and give practical advice. For installations outside the UK, we can often arrange for a similar consultation with your local Authorised Priorclave Distributor or one of our  factory-certified authorised service agents (ASAs).

In terms of health and safety, if you are unfamiliar with running autoclaves, please refer to the UK Health and Safety Executive’s Guidance Note PM73, which covers all aspects of laboratory autoclave safety.

The VENT outlet should be connected to a drain system (sealed drain if used for waste loads, but open is fine for standard sterilising). You could opt to simply pipe this down to a ‘catch bottle / tank’ to allow steam to condense and then you periodically empty the container.
Please note that the vented steam could be hot (typically 104 degrees during a process called Free-Steaming).
Further information on autoclave installation and positioning can be found in our datasheet A Guide to Autoclave Installation (found under downloads/instruction-sheets/ on this website).

It is recommended that a minimum of 500 mm (20 inches) on each side and at the back of the autoclave is required for Service Technician access.
All autoclave services should be positioned within a maximum of 2 Meters (6 feet) from the autoclave.

You may also find our Guide to Autoclave Installation helpful for this and other aspects of autoclave installation

For best results (and the most pleasant work environment), install your autoclave in an air-conditioned, well-ventilated space.  All autoclaves release steam and heat during their process cycle, and this should be taken into consideration when choosing a site in your laboratory in which to install your autoclave. Regardless of insulation arrangements employed to reduce the temperature of the autoclave, the outer casing of all autoclaves will emit heat into the work area. For the comfort of staff, it is recommended that autoclaves are installed in air conditioned areas. Heat output from the autoclave will vary at different stages of the cycle.

Heat Output

To assist with this question we have compiled a Power Ratings and Heat Dissipation Table.  The output from the autoclave is cyclic and varies throughout the cycle with the heat being put into the system during heat up and sterilising time and with this stored heat being released into the area around the autoclave mostly during cooling – a large amount at first, decreasing as the autoclave cools. Some heat will also be retained by the load and much of that will be released into the room on unloading.

To some extent the absolute amount of heat released depends on many factors not least the type and size of load being processed and the type of cycle but a good rule of thumb for the thermal loading placed on the air conditioning and ventilation system by the autoclave is approximately one third of the total heater power of the autoclave for each cycle.

• If the autoclave is steam heated from an external supply then a good indication can again be gained by checking the heater power of the corresponding electrically heated model in the products section of the website.
• Models with internal steam generators, although these are heavily insulated, will give off a little more heat as the generator is running throughout the cycle and even when the autoclave is not in use.
• Models with a steam jacket will give off a little less heat as the jacket is insulated and if water cooling is used the heat is taken out to the drains rather than going into the laboratory.
• Autoclaves piped to a closed drain or fitted with exhaust cooling condensers will give off less heat in the room as much of the heat emitted as steam during the cycle time will piped to the external drains.

Steam

If correctly installed as described in the installation manual, there should be no steam emitted to the work area during operation. There may, however, be some steam emitted when the autoclave door is opened. Under normal circumstances, the thermal cooling lock will prevent the door from being opened until most of the steam in the chamber has condensed; however, under certain circumstances, such as when the thermal cooling lock override is used, significant amounts of steam can be released. Consideration should be given to how this steam may affect your facility’s smoke and heat detectors, other equipment, etc.

There are many factors that affect the temperature of the discharge steam/water. With no drain condenser fitted, the autoclave will be purging steam up to 121°C. All discharge will be through the vent outlet pipework. The autoclave can drain its water if drying options are fitted—this will drain the chamber after process countdown, with temperatures as high as 136°C.

With an exhaust cooling condenser fitted, the water temperature will be approximately between 40°C and 60°C. Please note that water can be drained through the manual drain at any temperature.

Depending on the output of the water softener used and the size of the autoclaves, the answer is yes. The water softener sold through Priorclave is a mid-range unit specified to be suitable for the smaller home with one bathroom and a standard “combi boiler” or gravity-fed hot water system. These softeners are also quite useful as they require no electrical installation as the recharging cycle is controlled by a water pressure powered clock mechanism.

The water output capability of our softener is specified as 20L per minute with a minimum of 0.6L per minute and a maximum of 31L per minute. This is more than enough to run an electrically heated autoclave, because we are only looking to replace between 0.25 and 40L (depending on the model and the type of cycle being run) within 10 minutes every few hours or so, and with the head start of a header tank on the back pre-filled with softened water.

We recommend a supply pressure of 3 Bar with a minimum pressure of 2 Bar and do not recommend going above 6 bar. The water pressure in our test bay can sometimes drop as low as 1 bar and generally the autoclaves will run on this for testing purposes (we are not worrying about the output temperature of the autoclave exhaust).
We specify a higher level of pressure because:

• Water pressures can drop from time to time
• We want to ensure sufficient waterflow to maintain the drain condenser (where fitted) at maximum efficiency
• where the is a high demand for water from the autoclave usually vacuum pump, steam generator filling pump, possible the water jacket and Exhaust cooling condenser running at once, the vacuum pump cuts out intermittently when its feed tank can’t be filled quickly enough. In extreme cases this cutting out would be enough to abort the cycle on the time out protection for the vacuum part of the cycle.

Yes, all of our non-vacuum models can be configured to be “plug-n-play,” with only an electric cord connection. Benchtop models can also be placed on mobile carts, to be rolled from one area of the lab to the other.

The VENT outlet should be connected to a drain system (sealed drain if used for waste loads, but open is fine for standard sterilising). You could opt to simply pipe this down to a ‘catch bottle / tank’ to allow steam to condense and then you periodically empty the container.

Please note that the vented steam could be hot (typically 104 degrees during a process called Free-Steaming).

Further information on autoclave installation and positioning can be found in our Guide to Autoclave Installation.

Total hardness in terms of CaCo3: < 50mg/L (50ppm)

Conductivity: > 15 microSiemens

For more information about water quality, check out our whitepaper on Water Quality and Management.

When in doubt, it’s always best to have water tested. This can save you thousands in service costs, and greatly extend the life of your autoclave. Using a hard water supply will lead to a build-up of scale that will damage the heaters and other parts of the system, and could invalidate the warranty.

If in the first six months of operation you observe hard-water scale or other water-quality related issues, refer back to the Installation Manual and have your water quality tested. You can always contact us for advice on how to proceed.

Even “soft” water supplies contain trace minerals. These will slowly accumulate in autoclave chambers and plumbing, and on heating elements. Regular cleaning of your autoclave pressure vessel will guard against any build-up of these.  See your Operation Manual for details.

Soft water is the most reliable, and least expensive, source for sterilisation. Purified water is best suited for specialty applications like medical device or GMP production. Because it is highly corrosive, purified water requires stainless steel pipework, which is quite costly, and even then presents additional challenges for proper maintenance. Research-grade autoclaves can be configured to use either common soft water, or purified water.

Because Priorclave autoclaves use water conductivity to detect the water level in the chamber and protect the heaters the use of deionised (DI), pure, or distilled water is NOT advised. Additionally ultra-pure water has a corrosive effect on the copper pipework and brass fittings used in the autoclave. We recommend the use of a softened water supply to protect the autoclave heaters from the effects of lime scale.

For more information about water quality, check out our paper Priorclave Water Quality Requirements.pdf.

Yes, you can do so if you choose but although we strongly recommend the use of a softened .water supply for the autoclave chamber in order to protect the autoclave heaters from the effects of limescale we do not recommend connecting softened water to the condenser or other ancillary items because:

1) The water usage will be high and therefore expensive
2) It is unlikely that the softened water will be at the recommended pressure of 3 Bar to allow the condenser to work efficiently.

It is for this reason that two water inlets are fitted to many Priorclave Autoclaves; one for the autoclave itself and the second for any ancillary equipment.

Many areas have hard water. In order to protect the autoclave’s in-chamber heaters from limescale, we recommend you use a water softener. But your autoclave may have ancillary equipment (such as exhaust cooling condensers and vacuum pumps) that consume water, but do not need a softened water supply. In fact, they may function better when directly connected to the municipal water supply. As a result, in many cases, we build units with two water inlets: One for the water softener connection to the steam-generation system, the other for the ancillary equipment to connect directly to the municipal water supply.

In general there is no harm in using a softened water supply for ancillary equipment, if you keep the following factors in mind:

1. The volume of water used by a vacuum pump or exhaust cooling condenser is fairly high. You’ll need to account for this high demand and choose a larger water softener to accommodate it.
2. Vacuum pumps need decent water pressure to run efficiently.  A direct connection to the municipal water supply will tend to have higher pressure than a connection plumbed through a water softener.

Water pressure is not critical for the water filling system used by the autoclave for sterilisation, which is why it can be reliably supplied by a residential water softener.

Unlike some other steam heated systems the safety valve does not operate during normal running. It should actually never open at all except during routine annual testing.

We strongly recommend that the safety valve outlet of the autoclave is left OPEN so that, in the event of a malfunction, the excess pressure is expelled without hindrance and the main pressure vessel is safe and avoids potential catastrophic failure.

This arrangement also gives an audible and visual indication to operators that there is an issue with the autoclave.

We suggest that if any pipework is fitted to the valve outlet that this is only to direct the output of the valve to the floor with the minimum number of turns possible so as to ensure free flow.

Yes, if used for processing contaminated materials or if the autoclave has any form of active air removal system. Exceptions are rare.

Please refer to our Guide to Autoclave Installation for more details.

We can connect to a sink drain so long as it is vented properly (in accordance with plumbing codes) and not too high above the finished floor (relative to the autoclave chamber drain).

An extractor hood will help reduce steam and heat build-up in the room, and help to reduce odors—particularly if the unit is placed in a small room, or run on a regular basis. If disposable plasticware is being processed, then an extractor hood should be considered, especially if there is a risk of potentially harmful fumes.

That said, please bear in mind that the air handling systems of modern laboratories are quite sophisticated. We recommend consulting with a qualified engineer before making any decisions that may affect building HVAC systems. If necessary, research-grade autoclaves can interface to building systems to provide proper on-demand ventilation.

Although it is impossible to say how much water an autoclave will use without knowing a great deal about your operation, we can offer a rough guideline.  As a rule, benchtop models with condensate bottle exhaust will consume as little as ½ liter per cycle.  Models with drain condenser exhaust cooling will consume 15—25 gallons per cycle.

In the interest of accuracy, we gathered the following data by monitoring water consumption on an autoclave with a fairly popular laboratory configuration (a 150L Priorclave front-loader with a vacuum system and drain condenser) running standard sterilisation cycles:

Autoclave Use: On average for a normal cycle, around 3.3L is lost as vented steam from the autoclave chamber.  This is replenished by the water fill system at the end of the cycle. (The chamber holds around 12L.)

Vacuum Pump Use: This varies widely by cycle type, but on a cycle with the standard two pre-heating vacuum pulldowns and 12 post-cycle vacuum pulldowns, around 35L of water is used per cycle. If only a pre-heating vacuum is used, then the water consumption drops to around 10L per cycle.

Exhaust Cooling Condenser Use: This also varies by cycle (the condenser is thermostatically operated, and this only runs as needed).  On a cycle with the standard two preheating vacuum pull-downs and 12 post cycle vacuum pulldowns, the drain condenser consumes around 10L per cycle.

Although this is not an exhaustive list, the following things need to be considered when deciding if items can be autoclaved:

• Is this intended to be a re-usable item? If so, then you must consider the material that the item is made from. Any material that will not withstand the set sterilising temperature (usually between 121º and 134º) should not be autoclaved.
• Volatile flammable items should not be autoclaved in a standard laboratory autoclave—especially those with heaters within the autoclave chamber (as is the case with most Priorclave units shipped). 
• Even with non-flammable chemicals, you should note whether the chemical is likely to degrade silicone, Viton, or other high-temperature rubbers. Your Priorclave’s seals and gaskets are made of these materials, and may be damaged if you process such chemicals.
• Regarding corrosive chemicals: the chambers of all Priorclaves are made of corrosion-resistant grades of stainless steel—nonetheless, we still recommend avoiding routine exposure to corrosive chemicals like hydroxides and chlorine.

Radioactive materials should not be autoclaved. These can accumulate in the valves and pipework, creating hazards when servicing the autoclave at a later date or when disposing of valves and pumps that may need replacement during the life of the autoclave. In addition to this, radioactive material may be carried out in the autoclave exhaust and drain into the drainage system. Despite what you have learned from the Spiderman and Incredible Hulk franchises, the slapdash dissemination of radioactive material generally has wholly negative outcomes for all involved.

Where fitted, the manual drain can be used to remove the standing water from the vessel during the course of weekly or monthly maintenance. The procedure is as follows:

1. Unlock and open the manual drain with the key provided.
2. Drain the standing water into a floor sink or other receptacle.
3. With the vessel empty, clean the heating elements with a damp cloth to remove any build-up or lime-scale and prevent the accumulation of spilled media or potentially corrosive chemicals.
4. Close and lock the manual drain.

Alternately, a wet/dry-type vacuum cleaner or a siphon pump can be used to remove the standing water.

There is no need to be too alarmed by these types of noises. Within the condenser and pipework there will be a constantly changing mix of hot steam and cool or cold water, and the mix will create differing gaseous pockets at different stages within the pipework. It may not be consistent between different autoclaves as it very much depends on a host of variables such as pipework length, route, size, temperature of water and steam, and even minor manufacturing differences.

There are no moving parts or excessive pressure within the system, so it is perfectly safe.

However careful you are, autoclaves can get dirty inside after a time and need a bit of a clean-up, it really depends on how dirty and how often as to what the best approach is.

The official approach is stated in our manual as follows: What we say about this in our manual is as follows: “Grade 316L stainless steel is employed to reduce the corrosive effects of substances such as hydroxides and chlorine. However we recommend that the interior of the vessel is kept free of such potentially harmful substances and is regularly cleaned out with softened water. The use of chlorine based or other aggressive cleaners is not recommended. Exposure to such chemicals could damage the surface finish and the integrity of the pressure vessel and door. Care should also be taken not to routinely introduce such chemicals where they are used to pre-wash items that form part of the load. In such cases the items should be thoroughly rinsed before autoclaving.”

Practically speaking though, if you intend to regularly clean up the inside of the autoclave you really should avoid using chlorine or ammonia based cleaners as over time they will have an effect on the inside surface of the autoclave vessel, effectively making it appear dirtier more quickly. Over longer periods they could corrode the pressure vessel and door.

For regular cleaning some water and a plastic scouring pad is best. Do not use a metal abrasive pad as this will leave rusty residues in the pressure vessel.

You may find that using a wet/dry vacuum cleaner will be useful to change the water during rinsing. Alternatively we can supply a small syphon pump to assist in this process.

If it’s a clean up after a long period of time or after a spillage then initially we would suggest a mild acid like phosphoric acid (kettle descaler) to help with a big clean up but be sure to thoroughly rinse out the chamber afterwards as unless you have a cycle running that drains the chamber at the end then electrolytes will tend to concentrate in the water reservoir over time.

Although water does get used during a cycle in the steam generation process, we would recommend exchanging water on a weekly basis. While empty, inspect the vessel surface and probes, wipe down if necessary, and refill with softened water.

Priorclaves can be specified to use any type of water source, but most are built to operate most effectively with standard softened water. A unit specified for standard water may not function efficiently—and can even be damaged—by demineralised, deionised (DI), distilled, reverse osmosis (RO), “high-purity”, or ultrapure water (UPW) supplies.

Yes. This is a simple operation (only requiring a few minutes), and changing this Tactrol parameter can be done by a supervisor via the customer settings menu. If you have either a 5 or 10 program memory fitted then a different temperature can be set for individual programs.

Please contact support, and we’ll walk you through making this adjustment. Such assistance is covered by your autoclave’s free lifetime technical support alternatively contact your local Priorclave Distributor for details.

Yes! Delayed Start is standard on all Priorclave models, and can be set from the Tactrol control panel. Please refer to your Operation Manual for a full list of functions and settings. You can also refer to Priorclave’s Customer Setting Instructions sheet.

Because it harnesses high temperatures for long periods of time, any autoclave can have a major impact on your building HVAC system. Some aspects of Priorclave’s design (such as cold idling) mitigate this impact. Our team works hard to guide every autoclave buyer to a properly specified and installed unit. This minimises the impact on HVAC operation.

In general, the thermal load placed on your air conditioning and ventilation systems by your autoclave is approximately one third of the total heater power for the unit’s first hour of operation. The output from the autoclave is cyclic and varies throughout the cycle, but this figure is a good guide for a thermal load calculation. If you’re using a direct steam heated unit, look up the wattage of the corresponding electrically heated unit.

This is our most frequently asked question—especially from new Priorclave owners. Do not worry! The door can be tricky at first, but the design allows for very safe single-handed operation.

Press the “Door” button on the control panel. There will be a beep and the message “Hold” will be displayed on the digital temperature display. Wait for a short time until the temperature display returns to normal. There will be another beep and the door indicator will light up. Press the Door button once more to release the lock.

Open the door as described below:

Front Loading Models

1. Lift the locking handle up.
2. The handle should spring out into its unlocking position.
3. Lift the handle fully upwards to unlock the door. The handle is now in its safety lock position, allowing any residual pressure inside the autoclave to escape harmlessly.
4. Nudge the handle down to release it from the safety position.
5. Push the handle in as far as it will go.
6. Move the handle fully upwards to its parked position.
7. With the door unlocked, carefully pull the door open.

Top Loading Models

1. Pull the locking handle to the left.
2. The handle should spring out into its unlocking position.
3. Pull the handle fully to the right to unlock the door. The handle is now in its safety lock position, allowing any residual pressure inside the autoclave to escape harmlessly.
4. Nudge the handle forwards to release it from the safety position.
5. Push the handle in as far as it will go.
6. Move the handle fully to the right to its parked position.
7. With the door unlocked, carefully lift the door open.

Bench Top Models

1. Lift the handle fully upwards to unlock the door. The handle is now in its safety lock position, allowing any residual pressure inside the autoclave to escape harmlessly.
2. Push the safety latch forward with your thumb to release it from the safety position.
3. Push the handle up as far as it will go.
4. With the door unlocked, carefully pull the door open.

Top Loading Compact Models

1. Pull the handle fully to the right to unlock the door. The handle is now in its safety lock position, allowing any residual pressure inside the autoclave to escape harmlessly.
2. Push the safety latch down with your thumb to release it from the safety position.
3. Push the handle to the right as far as it will go.
4. With the door unlocked, carefully lift the door open.

Rectangular Door Models

1. Fully unwind the lower locking hand-wheel and, if fitted the central handwheel.
2. Next carefully unwind the upper hand-wheel. This will slowley jack open the door, while retaining it, allowing any residual pressure inside the autoclave to escape harmlessly.
3. Complete unwinding the upper hand-wheel.
4. With the door unlocked, carefully pull the door open.

For illustrations on how to open the door, please refer to the Operation Manual that you received with your autoclave.

A copy of the manual was sent to you along with your autoclave. The Pressure Vessel Certification can be found at the back of the manual for the autoclave. If it is not located there, please contact us and we will be able to send you a digital copy.

All Priorclave Autoclaves arrive with their Initial Opening Instructions and Manual in an envelope attached to the outside of the unit. If you have lost any of these, you can find PDF versions in the Downloads section of our website. Replacement manuals can also be ordered by contacting us directly.

Yes, you can change the print interval. By default it is set to print relevant data every three minutes during the cycle dwell period. The print interval is one of the many functions that can be changed from the front control panel. Please refer to your Operation Manual for a full list of functions and settings. As a quick reference, you refer to Priorclave’s Customer Setting Instructions sheet.

Certainly! The time and date settings (along with other common functions) can be adjusted directly from the Tactrol control panel. Please refer to your Operation Manual for full instructions.

As a quick reference, please refer to Priorclave’s Customer Setting Instructions.

This scenario sounds like one of the START criteria has not been met. (The Autoclave control system requires a number of parameters to be met before it is considered safe for the Autoclave to start a process cycle.) Please check the following:

1. Is the door correctly and fully closed?  There are several micro-switches that monitor the door position. Opening and then firmly closing and sealing the door should remedy this.
2. Does the pressure gauge read zero?  Open and then reseal the door.  The gauge should now read zero. If this gauge reads anything other than zero on an idle autoclave that has just been closed, it implies that there is a fault with the pressure switch or the pipe-work between the switch and the vessel.
3. If you have in-chamber heating, are the Low Water Probes clean and is the water level touching the highest probe?  If the probes are dirty or the water level is too low, the autoclave will not start.

If these steps fail to remedy your problem, please contact support for further assistance.

This is because the Tactrol Control System is waiting for a response from the printer before starting the heater. Either the printer is not installed correctly, or the connection to the printer has been lost. Please follow this procedure:

1. Simultaneously press the up/down buttons directly below the green dwell time display. The autoclave should beep. The temperature display will change to “0” and the dwell time display to “000”.
2. Press the up button below the dwell time display until it reads “011.”
3. If the temperature display is showing anything other than “0” adjust it down to “0” using the up/down buttons below the temperature display.
4. Now reset the controller. If your autoclave includes a Multi-Program Memory unit, turn the Setting Lock key from position 1 to position 3 and back again. If you do not have a Setting Lock key switch, then reset the controller by pressing the small black reset button labeled “Tactrol Reset” located at rear of control panel.

The autoclave should now function correctly. If not, please contact support.

This is the intended behavior of your autoclave, and is for your safety. The thermal lock is fitted as a safety measure and has become required for all laboratory autoclaves manufactured to BS2646 after a number of accidents where glass bottles containing liquids or growth media exploded on exposure to cold air when the autoclave door was opened. The standard requires that the door cannot be opened when the temperature of the load inside the autoclave is above 80°C.

Liquid loads, as a rule (thermodynamically speaking), cool much more slowly than the autoclave chamber. Based on our experience and measurement of a variety of different loads, we’ve found that the control probe needs to be approximately 30 degrees below the desired 80°C safety threshold in to be sure that the load itself is at or below 80°C. This is why thermal lock releases when the temperature of the interior of the autoclave reaches 50°C.

The thermal lock is a safety guard that we have set to this temperature to ensure that all load types and conditions complete the sterilisation cycle safely, from the time the door closes to the time it opens.

For non-liquid loads It is possible for a supervisor to override this safety feature with the Thermal Lock Override Key, please refer to the operating manual for details.

The Thermal Lock temperature can also be modified, Contact us for a waiver and further details.

Something is wrong. A complete list of error codes is included in your Operation Manual. If your autoclave includes a printer, the code and a short explanation will be printed out.

Alternatively, you can refer to our Error Codes List for more detail.

The Service Fault Light comes on every 6 months or once 500 cycles have been completed since it was last reset.

Although the autoclave function will not be immediately affected, this means that it is time for Preventative Maintenance to ensure the continuous operation and safety of your autoclave.

Please contact your local service agent for support and we will send a trained technician to work on your autoclave!

There is no need to be too alarmed by these types of noises. Within the condenser and pipework there will be a constantly changing mix of hot steam and cool or cold water, and the mix will create differing gaseous pockets at different stages within the pipework. It may not be consistent between different autoclaves as it very much depends on a host of variables such as pipework length, route, size, temperature of water and steam, and even minor manufacturing differences.

There are no moving parts or excessive pressure within the system, so it is perfectly safe.

We can certainly offer training on the use of Priorclave Autoclaves and on Autoclaving Principles. Please contact us for a quote.

We maintain a stock of spares (or replacement items) for our autoclaves for a minimum of 7 years after manufacture and the most commonly used items are held in stock for despatch to customers.

In many cases our local distributor will hold a small stock of commonly used parts.

Outside of the UK, regulations vary from one country to another, but usually require some form of routine inspection. Check with your insurer to find out what is required in your jurisdiction. Your local Priorclave Distributor may also be able to assist you with this.

Priorclave support a global network of exclusive distributors, with sales and service offices throughout world.  These organisations are fully trained by Priorclave to handle every aspect of autoclave specification, installation, and maintenance, and are also intimately familiar with concerns unique to your region.

Also many common issues can be resolved “remotely” by our Technical support team.

Please contact your Local Distributor or Priorclave Technical Support for more details.

The routine operator maintenance includes daily, weekly, monthly, and biannual tasks (these tasks are mostly just keeping the unit clean and occasionally greasing the door gasket). For most applications and facilities, this is sufficient to keep your Priorclave running in good order from day to day.
We strongly recommend regular Preventative Maintenance to keep the autoclave running well, usually every six months please contact your Local Priorclave Distributor for more details.

All Priorclave autoclaves come with a 12-month limited parts warranty a 10-year pressure vessel warranty, and unlimited lifetime technical support.