Increasing Stability Storage Capacity

Installing Stability Storage Chambers – Factors to Consider

Q1 Scientific is a stability storage facility, providing industry-leading temperature-controlled storage. Over the years we have installed over 30 walk- in stability chambers along with numerous types and sizes of reach-in units.

We typically add between 4 to 8 new storage units per year depending on capacity requirements. The process of adding storage capacity to a facility deserves a lot of thought and design. To ensure the best solution is discovered, the process must be broken down into step by step segments. The following calls out the steps required to get from initial planning to complete validation of a typical walk-in stability storage chamber.


Style and Size

The first point of investigation is ‘how much storage do I need, now or 3 years from now’. This will have a big bearing on the different paths you may decide to go down. If the storage requirement is likely to be less than 1,000Litres, a reach-in style unit is probably a good option. Reach-in units typically range from 25L to 750L. Any program which will require above 3,000Litres storage is probably leaning towards justifying a walk-in chamber.

With walk-in chambers, the options are almost endless. A chamber can be designed and built to any size or shape. Capacity will typically range from 8,000Litres up to 200,000Litres. An important point to remember however, when installing a walk-in chamber, is all capacity may not be useable. While reach-in units are typically very efficient in their use of space, walk-in units will have ‘dead-space’ such as corridors, ducting areas or hard to reach shelving corners which reduce available storage space. Additionally, space must be allowed for air circulation and taken into account when designing the layout and shelving.


Storage Conditions

Due consideration must be given to the storage conditions which are required on site. If a study is to be stored at 5⁰C, a walk-in room might make most sense. However, if samples are to be stored at 40⁰C or higher, the operator retrieving samples must be considered in terms of the significant temperatures within. In this case, a reach-in unit or multiples might make for easiest operations. There is a helpful correlation in stability storage between maintaining storage conditions and capacity required at each condition. Typically, the storage conditions which require the most capacity are the easiest temperature and humidity’s to maintain, making them most suited to large walk-in chambers.  For example, the bulk of samples in a stability study will typically be stored at 5⁰C or 25⁰C/60%rh. These conditions are relatively easy to maintain in larger units. A small number of samples will typically be stored at accelerated conditions such 40⁰C/75%rh. These conditions are more difficult to manage and thus would be more suited to a reach-in unit.



Backup redundancy is a must in such a critical process as stability storage. This can be achieved in a number of ways. The first option is to include a duty-standby system where all controlling equipment is installed in duplicate. This allows one system to control the chamber and in the event of a malfunction, control can be swapped over to the second unit, while the first is investigated/maintained. This system works well but greatly increases the cost of install, validation and maintenance.

Another option is to decide on a type or model of equipment and use the same format for all future installs. With this in place it is possible to store all required replacement parts on site without needing a multiple of different models of pumps or heaters etc. This system works well and will keep costs down, but it can be difficult to keep to one model as different needs arise over the varied nature of samples and storage conditions. An on-call maintenance team must also be in place to facilitate this system, as time is of the essence in the event of a failure.

The final option is to have a spare chamber available for all conditions currently in use. This will only work with certain conditions, a chamber that provides chill conditions such as 5⁰C, is unlikely to be able to also provide up to 40⁰C or humidity control. This also means, in the event of a failure, all samples will need to be physically moved from one chamber to another, which provides more challenges.

User Requirement Specification (URS)

Once the design has been decided it is immensely important that all specific requirements are clearly communicated to the supplier or manufacturer. A User Requirement Specification document should be completed before placing the order. To complete the document, a group discussion should be completed with all stakeholders included. Management, operators, maintenance, quality, finance and any other relevant personnel should be brought together to tease out all requirements.  Failing to include all affected personnel at this stage will result in costly headaches at a later stage as the unit is being used and maintained. Once the document is complete and all departments have signed off, the approved supplier should be consulted to ensure they can adhere to all stated requirements. Again, anything which is left unanswered or unconfirmed at this point will cause problems down the line, which may result in extra costs. It is best to lay out all requirements very clearly and allow the supplier to opt out of the project if they cannot meet said requirements.

Figure 2: Sample version URS


Validation is the final step in completing the install of a reach-in or walk-in stability chamber. It is the process which confirms the equipment being supplied and installed performs exactly as expected and required. Typically, an install company will also provide validation services and if the option is available it makes sense to have one company complete the whole process. Along with the performance requirements, the URS should also clearly state the validation needs of the end user. For example, processes such as temperature and humidity mappings should clearly set out the duration, number of loggers and tolerances. Validation should be treated as one of the most critical steps in the whole process, it will typically include the following items: Installation Qualification, Operation Qualification, Performance Qualification, System Calibration, Temperature and Humidity mapping, Shelving/Storage Area Configuration.

Figure 3 All data-loggers must be calibrated before use



When the project reaches the point of completing the validation, it is getting very close to being available for storage. However, before any samples can be placed within, a validated monitoring system for temperature and humidity must be in place. Monitoring provides continual feedback on the performance of the room and conditions samples are being exposed to within. Where a company is adding extra storage capacity, it is likely an existing Central Monitoring System (CMS) will be in place. In this event, extra dataloggers/recorders can be added to the existing system with little fuss. New loggers must be validated through IQ/OQ and if possible, this process can be tied together with the overall validation of the chamber.

If a new CMS system is required, there are many off-the-shelf options available on the market today. Some of the main considerations to assess before choosing a supplier are; service level backup, lead time on new loggers or spare parts, 21 CFR Part 11 compliance/certificate, GAMP rating, wired or wireless, server or cloud based. An important decision to be made is around wired versus wireless dataloggers. A lot of the systems on the market are moving towards wireless monitoring, which includes a ‘base station’ and wireless dataloggers. The dataloggers then transmit the temperature and humidity readings within the chambers to the CMS system, via the base station. The big advantage here is the lack of cabling require, while there is also no need to create any openings in chambers to allow connectivity. The risk of losing connectivity and the distance from the base station
must be considered.

Remote access is another feature which can prove very useful around monitoring. If a chamber provides an alarm or alert to the user, being able to access the CMS system remotely, can speed up reaction times. If the site is not in operation 24/7, there must be a responsible person ‘on-call’ at all times to react to any excursions.

Figure 4: Sample Central Monitoring System


Finally, once the chamber is ready to use and has been signed off from validation, a schedule of maintenance should be created. Regular preventative maintenance (PM) should be planned at least once a year, if not more regularly. Together with the maintenance personnel and manufacturer/installation company, a checklist of parts and functions to inspect should be created. Each time a PM is completed, the checklist should be completed and checked by the quality department. Spares should also be kept on site, with a log of all spare parts regularly updated.



As is clear from the above, there are a lot of considerations to be taken into account in the process of installing stability storage. This is only a small snapshot of the challenges to be faced and it should be remembered there are many more steps involved, not detailed above. A Quality Change Control should be opened to track all steps required to complete the project. While a Risk Assessment should also be completed to highlight any potential issues before commencing the project. A process flow diagram has been created below to detail the steps to be completed: