Types of alerts
A critical component of any monitoring strategy is determining how users will be alerted to a temperature excursion. Any system which requires users to periodically check the recorder will significantly delay response to an excursion.
Examples of visual alerts include the presence of lights or alarm symbols on the displays of recording devices.
Visual alerts will generally require staff to periodically check the recording device, and therefore may lead to a significant delay in an excursion being identified.
Audible alerts are normally linked to a refrigerator or freezer’s integrated monitoring system. They are an effective means of immediately alerting staff in the local vicinity to a temperature excursion.
There are limitations to be considered with audible alarms as they can be missed in the following scenarios:
- out of hours
- if the refrigerator is in a room without personnel nearby
- if the alarm volume is low in relation to the noise of the background environment
Audible alerts may be set if a refrigerator or walk-in cold store door has been left open for a set period. This is an effective way of preventing temperature excursions linked to doors being accidentally left open.
SMS message / Email / Telephone
Some recording devices may be linked to local networks and configured to send automated alerts via email, MSM and telephone calls in the event of an excursion.
Users are notified of excursions even when there are no personnel in the vicinity, e.g. out of hours. These systems provide the most robust means of alerting users to a temperature excursion.
Recording and silencing alerts
Alert systems should maintain a record of alerts. If they do not have this functionality, alerts should be manually recorded.
Alarms should not be able to be permanently silenced; if there is a function to silence an alarm (e.g. while stocking a fridge) the alarm should sound again after a defined period (e.g.10 mins) if the fridge is not back in range.
Setting temperature alarms
When setting up alarms, both the temperature set points at which the alarm will sound, and the alarm delay period must be established.
Alarm set points
For all thermometers, alarm points must be set at temperatures which will alert users to a temperature excursion.
Consider setting the alarm at a point before an excursion occurs. For example, a refrigerator should not exceed a temperature of 8°C, setting the alarm threshold at 7.5°C allows a user to respond before an excursion happens. However, if you set your alert at 8°C, you will have already had an excursion when alerted.
A delay may be set on the alarm to allow for acceptable small excursions without an alert, e.g. the transient rise in temperature associated with a fridge door opening.
The alarm delay should be set to as short a period as practically possible to both:
- prevent a delay in being alerted to significant excursions
- to increase the potential for detecting a refrigerator which is cycling in and out of the required temperature range
Review of monitoring data
Even when alarms systems are established, temperature data requires review to ensure there have been no excursions. The frequency of review will depend upon the type of recorder used.
Min / Max recorders
Temperature should be continuously monitored with the minimum and maximum (Min / Max) temperatures checked, recorded and reset at least once a day.
An independent daily check should be in place to ensure checks / resets have been carried out.
Data from temperature loggers should be reviewed periodically to ensure temperatures have remained within range and to detect developing trends, such as a fridge temperature that is gradually creeping upwards or downwards, which might indicate a developing problem.
If they are not stored automatically, data files from the logger should be periodically downloaded and retained on file.