Freezers are a critical element of the supply chain and storage of many different high-value products, including medicines, vaccines, laboratory samples (for hospitals and research institutions), foods and beverages, and specialty chemicals. These products must be kept cold in order to maintain their value.
For some products, like produce, the value decreases incrementally if refrigeration is not perfectly maintained, since this will cause the product to spoil more quickly. For other products, like vaccines, even a short refrigeration failure (leading to an increase in temperature referred to as an “excursion”) can ruin the material, deactivating it and causing its value to drop to zero. For vaccines and medicines, the cost of a freezer failure can exceed the lost value of the product if they are inadvertently administered to patients, potentially even leading to disease outbreaks.
Traditional upright freezers work through the cyclical evaporation and compression of a refrigerant. First, the liquid refrigerant passes through a small opening into the evaporator coils inside the freezer. The resulting rapid expansion of the refrigerant partially vaporizes and cools it, so it is able to extract heat from the freezer compartment. The refrigerant then passes through a compressor and a set of condenser coils outside the freezer compartment. In the condenser coils, the refrigerant returns to a liquid state, and rejects heat into the atmosphere. After condensing, the refrigerant again passes through the small opening and into the evaporator coils, restarting the cycle.
In this way, heat is pumped from the freezer compartment into the environment. To maintain a roughly constant temperature range, the cooling system is periodically turned off and on by a thermostat, which in more advanced units is tied to a programmable control-display board on the front of the unit.
While the technology behind freezers is quite mature, and they do the job of cooling exceptionally well, they do have moving parts and require electrical power, which means they are subject to random, unexpected failures which can endanger their contents. In this article, we’ll first talk about some of the common reasons why freezers fail, then the ways that you can prevent these failures from becoming more serious and costly events.
Interest in freezers, and refrigerated supply chains has recently increased, due to the expected rollout of a COVID-19 vaccine. However, most vaccines require constant refrigeration, as do the other high-value products we listed above, so this topic is continually relevant across several fields, from medicine to food service to research and development.
How Do Freezers Fail, and What Are The Consequences?
Freezers can have issues for a variety of different reasons. For simplicity, these can be grouped into a few common areas:
- Equipment failures. These are the mechanical failures that probably come to mind first. Compressor and fan motors, defroster circuit, thermostat, and relay switch failures, for example. There are also passive components that can fail, like the defrost drain becoming clogged. In rare cases, the sealed circulation loop can develop a leak. Note that federal law requires certification for technicians servicing some of these components.
- Control/display board failure. This is also relatively rare, but freezers with more complex control and display systems can fail due to problems with electrical components on the control board.
- Lack of preventative maintenance. This type of failure, which includes things like dirty condenser coils, excessive frost on the evaporator coils, or a damaged door gasket, are fully preventable with regular visual checks and a good preventative maintenance plan.
- Power outages. This is also straightforward (though not cheap) to respond to, through the use of backup power systems.
- Insufficient training. Frequent door opening, doors left open, or even inefficient placement of materials in the freezer can cause operational issues.
Note that the CDC provides thorough guidelines for the kind of training and preventative maintenance that can help to avoid many of these problems. The information provided by the CDC is meant for healthcare providers who store vaccines, but much of it is generally applicable to low temperature storage of any material.
Although many causes of freezer failure are simple and easy to detect and resolve, the consequences of a failure can be massive. A temperature excursion, at the very least, involves the need for manual intervention, and could cause loss of products and product recalls, having serious financial consequences.
But the losses could also go beyond just the material cost of the freezer contents. For example, the CDC recommends re-administering vaccines that are inadvertently given after experiencing temperature excursions. For frozen medical specimens, which may be irreplaceable, a freezer failure can have tragic consequences for those affected. In these situations, simple, preventable equipment failures have the potential to seriously damage public confidence in the organizations responsible for safeguarding the frozen materials.
In the case of FDA-regulated industries, there are also reporting requirements and regulatory consequences for refrigeration equipment failures. Note that FDA auditors can also confirm proper training and documentation during routine inspections.
4 Factors for Avoiding Asset Loss from a Freezer Failure
Factor 1: A well-integrated continuous monitoring system has been installed
In this context, well-integrated means that the monitoring system is set up to record and transmit temperature data so that it can be viewed remotely, and can generate customized, intelligent alarms (we’ll talk more about alarms in the next section).
In the event of a freezer failure, the presence of this type of monitoring system has a number of benefits. First, it is completely independent of the refrigeration equipment, including the on-board temperature controls, so that a failure of these controls- like a thermostat reading the incorrect temperature- will not affect the monitoring system. The sensors used in the monitoring system could also be more accurate than the on-board temperature measurement.
The second is that continuous, real-time monitoring allows a temperature excursion to be detected as quickly as possible, at a point when response time is absolutely critical.
Another benefit that should not be overlooked is that a frequent review of temperature data, as well as other operational information like door openings, can be used to prevent temperature excursions before they occur, by identifying the warning signs of an impending failure.
For these reasons, it is a huge advantage to use a continuous, cloud-based monitoring system such as DicksonOne. This type of system has become the state of the art, replacing older stand-alone data loggers that do not transmit data that can be visually seen immediately. . These older loggers can provide a detailed record of what happened during a failure, but generally cannot help to prevent failures or mitigate their consequences.
Factor 2: Alarms and notifications are configured properly
Modern, cloud-based monitoring systems have another important benefit, which is the ability to customize alarms. A thoughtful plan for alarm customization is part of an overall strategy to respond to a freezer issue as efficiently and quickly as possible.
Customization can also help to prevent “alarm fatigue”, which is a situation where staff ignores or disables alarms due to receiving excessive false and irrelevant alarms from an automated system. This is a highly problematic situation, since it can lead to real alarms being missed. This is addressed, in part, by setting up the system so that alarms are only generated when action by the staff is required. Historical data can be helpful to set these alarm conditions.
Here are a few tips for effective alarm customization:
- Target alert messages directly to maintenance staff, based on location and time, to ensure the fastest response. If reallocation of resources is needed, auto-escalate alerts to management.
- Include a description of the problem in the alert message, so that responding personnel will be prepared with the right equipment and replacement parts on arrival.
- Look back at monitoring data around the times of previous failures to determine the conditions where an alert should be triggered. In other words, look back at past temperature excursions to see if any patterns are present before failures take place, so that warnings are triggered if those patterns return.
Factor 3: Personnel are trained properly and equipped with a plan
Unexpected failures of mechanical refrigeration equipment are unavoidable. However, adequate training and preparation of staff in the event of a failure are completely under your control. Along with having the right continuous monitoring and alert system in place, the other key component to mitigating the effects of a freezer failure is training. For sensitive FDA-regulated areas, thorough training is actually required by law. Training includes proper operation of the freezer equipment and monitoring system, preventative maintenance, as well as what steps to take and who to contact in the event of an emergency.
A complete training plan includes clearly written procedures, and periodic staff training to make sure the procedures are being effectively communicated. This is especially true for emergency procedures, where response time is critical.
Factor 4: Calibration and maintenance are performed regularly
Looking back at the list of potential freezer failures, a number of these could be prevented entirely through a system of routine checks and preventative maintenance. For example, visual checks on door gaskets, condenser and evaporator coils, and performance tests of the thermostat and the relays connected to it. This is an area where you can work with the equipment supplier to develop an effective plan.
Likewise, you can also work with temperature monitoring experts to design and implement a robust strategy based on sound, accurate, and complete data. This also should include a calibration plan, where the sensors used for temperature monitoring are checked for accuracy before installation, and at regular intervals after that, by an accredited lab using traceable standards.
Freezers are a key element to the safe transport and storage of many types of high-value, sensitive products. While some freezer failures can be avoided through preventative maintenance, others can be mitigated by an integrated temperature monitoring system, combined with rigorous staff training. For a temperature monitoring system to be effective, it should be set up to continuously upload data to the cloud, with alerts set up to ensure fast response in the event of an equipment issue.
Using a third party temperature monitoring expert can often simplify the process of setting up this type of monitoring. Contact a Dickson expert today to speak with one.