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Why would you want a daily min/max graph?

datalogger | July 15, 2018 | blog

I actually wanted the headline to be “why the hell would you want a daily min/max graph” but that may have been too confrontational. It does, however, indicate how strongly I feel about this.

Just to be clear, before too many people jump to the wrong conclusion, I am asking why someone would want a daily min/max GRAPH.

To explain why I hate the idea I want to take a stroll down memory lane first.

Many years ago we only had thermometers for monitoring the temperature of fridges. To make the situation worse, the fridges were often domestic fridges with really poor control and the tendency to drift. The confusing temperature dial did not help matters.

Since the fridges were so unreliable it was important for staff to check the temperature often.

Min/max thermometers meant that it was possible to be aware of a problem even if you weren’t there when it happened.

At the same time, however, if there was a problem, you didn’t want to be using or selling stock that may have been compromised.

It was not practical to have someone check the temperature every 10 minutes. It was time consuming and was checking for a problem that rarely occurred.

Consequently there was the need to check the minimum and maximum temperatures daily (or twice daily). “Strive for Five” focused on this for the storage of vaccines.

A daily min/max record was required because it was the best solution at the time.

There was, however, one upside to the daily min/max – a list of 28 to 31 readings on a single page is very easy to look at and understand. If everything was fine (which it normally should be) then the daily min/max report was the perfect was to show that you were actively checking.

The min/max report was totally useless if things did go wrong. For example, what happens if you restock your fridge every couple of days and the temperature spiked to 12° each day, but only for 5 minutes. It’s not damaging your stock but the min/max report would show 12° each day.

A min/max report is only useful if the temperatures are within the required limits.

Unfortunately there are now too many procedures and requirements written around the daily min/max recording.

Temperature loggers solve all the limitations of a daily min/max report. When something goes wrong you know when it starts, when it finishes, how hot/cold it actually got to, and how long it was at the extreme temperature. That is critical information when considering if stock needs to be disposed of or customers notified.

The downside of temperature loggers is that if you wanted to print all the data, it would take many pages. That’s a waste of paper all for something that someone won’t actually look at.

There are two possible solutions:

  1. A daily min/max report: This is a great way of summarising the data, but you will have to return to the software to see what actually happened if something did go wrong.
  2. A graph.

And just by the descriptions above, you can see the simplicity in a graph. It shows everything in a fraction of a page. A picture is worth more than a thousand words.

Which brings me back to my original question – why would you want a daily min/max graph?

You want to strip all the information out of the graph and just be left with the daily peak and trough. You have no idea when these peaks and troughs started, if there were numerous ones or just one, and if you have a problem. You still have to go back to the data to see what actually happened.

The graph may look nice and simple (two relatively smooth lines) but it has lost 90% of its meaning.  I would go as far as to say without that 90%, the other 10% effectively becomes useless.

While a daily min/max graph sounds fancy and friendly, it’s a rust bucket with a fresh coat of paint.

Let’s get with the times and make the most of the simple, easy and affordable technology that we now have, and stop making compromises that we don’t need to anymore.

Have we lost our way with vaccine monitoring?

datalogger | November 15, 2017 | temperature logger,Vaccine Temperature

Have we lost our way when it comes to monitoring vaccine fridges?

We have been selling temperature loggers for vaccines for nearly two decades. Over that time we have seen a huge change in the way that vaccines have been stored.

I’m starting to question whether we’ve lost sight of what the problems were and why we do things.

The problems with the way things used to be

Twenty years ago it was not unusual to see vaccines being stored not only in domestic fridges but in bar fridges with freezers. What this meant was that we had vaccines that were being stored in an item where

  • we had absolutely no idea what the temperature was
  • the temperature was poorly regulated
  • there was a really good chance that the vaccines were freezing.

“Strive for five” to the rescue

“Strive for Five” came along with the emphasis on trying to make sure that vaccines were kept at 5 degrees. At the same time they highlighted that the guidelines were about keeping the fridge between two degrees and eight degrees.

As part of the document they discussed the ways of making a domestic fridge suitable for use in storing of vaccines. It had tips about how to pack it up with water bottles to try and regulate the variations in temperature. It talked about using a min/max thermometer to make sure that you knew that the temperature was correct.

There was a very strong need to check the thermometer regularly because you were relying on a dial that you had absolutely no idea what it meant and to control a fridge where you could not see what the temperature was. If you adjusted the dial you had no idea whether or not you were making it warmer or colder.

As the temperature changed throughout the year, season to season, the performance of the fridge would naturally change as well.

All of these factors combined meant that it was critical to be monitoring your temperature daily. It was critical that you were using a max to monitor to check the temperatures because you needed to make sure that at all times the temperatures were within the range.

Temperature loggers were a great solution for showing what was happening within the fridge throughout the day. It provided more meaningful data than just a min/max temperature and often provided valuable data when things went wrong (and they often did).

What has changed?

Over the past 20 years we’ve seen a total ban on bar fridges with freezers. And to a very large extent, we no longer see domestic fridges being used.

Instead we see vaccine fridges being within the medical industry. This has automatically solved many of the old problems.

The benefits of a vaccine fridge

We now have a fridge with a built in computer. It’s now controlled to turn on and turn off at certain temperatures. Previously you never had control of the lower temperature, only the higher temperature. Now the same fridge has control of the highest and lowest temperature.

This means that a vaccine fridge will no longer accidentally freeze.

Add to this the fact that you’ve got a temperature display on the front of the fridge and your staff know all the time what the temperature of the fridge is.

But here’s the really big change – even if your staff did not know what the temperature was, the fact is that the fridge itself has a built in audible alarm.

Practically, this means as soon as it gets too hot or too cold it will tell you that there is a problem. Your staff don’t actually need to check the fridge anymore to see that there’s a problem because your fridge will do it for you.

All these extra features help ensure that the problems that we faced 20 years ago have largely been dealt with.

Then the question is

Why do we check the temperature?

I think that there is still a huge benefit in having staff check the temperatures once a day to remind them that temperature is important. You want staff to know that they shouldn’t be leaving vaccines out that they know they shouldn’t leave the fridge door open, and that it’s important to put stock into the fridge as quickly as possible. It’s also important for them to know that if the fridge fails if the power fails that there is a critical issue at hand and they need to be considering what to do to keep the vaccines within the fridge safe.


This is about having the right culture. Just checking the temperature won’t create the right culture, but if you have the right culture, it will help support it.

Are temperature loggers are obsolete?


There is still a key role that temperature loggers play in the monitoring of vaccine fridges, but it’s no longer to tell the person whether or not the fridge is okay because the fridge is largely doing that itself.

Instead, the roles of the temperature logger are.

  1. To prove that everything was okay in the fridge.
  1. To give a detailed account of what went wrong if something went wrong. Remember it’s likely to be the fridge that told you in the first place that something went wrong, but it can’t tell you exactly when and for how long.
  2. The temperature logger acts as a policeman. What I mean by that is the temperature logger is a method of validating whether or not your fridge’s temperature is actually correct. There is a chance that your fridge is monitoring the wrong temperature therefore controlling the wrong temperature, and therefore the fridge will be at the wrong temperature.

Then the question is…

How often do we have to check the temperature logger?

There is a big push in the industry to be checking the temperature logger once a day because that’s how often we used to have to check a min/max thermometer.

Here’s the problem – the reason why we were checking a min/max thermometer once a day was because we had no idea what the fridge was doing.

We had no idea if it was failing and we had to be finding that information out as quickly as possible so as to not give too many people vaccines that have frozen and become ineffective.

Now we’v got a fridge that does all of that.

Then the question is…

How often do we have to police the police?

Any other industry would say that you need to validate a thermometer or a temperature logger typically once a year. The assumption is that a temperature monitoring device is basically fine and just needs the occasional checkup.

Why are we double checking vaccine fridges every single day when the norm within the temperature monitoring industry is typically once a year?

We’re now policing the police once a day just to make sure that they haven’t drifted off. We’re hyper paranoid!

How often do we have to validate that the fridge is doing everything correctly?

Or putting it another way…

How often do we need to download the results from a logger?

In theory you could do it at each audit. Most loggers don’t have sufficient memory and so would require a download prior to overriding data. Once a month or once every six months and you will have the information you need.


I do not recommend that because one of the biggest issues that we still have with temperature loggers is that the battery will fail and you will lose data. You want to download your data frequently enough that you have enough information to prove that your fridge is working effectively.


Practically we advise people to download the results once a fortnight, week or month.


And yet there is a demand to download them once or twice a day.

My question is “have we lost our way?”


Have we become too paranoid?

Putting in place a daily check based on the way we’ve always done things means we have actually lost sight of what the problem was that we were trying to fix. Instead, now we’ve got a process that is so much slower and more cumbersome than it was 20 years ago. We’re penalizing people for using a temperature logger when it’s meant to be making life easier.


Let’s use a bit of common sense and work out what we are trying to achieve.

Car temperature reaches 70°C on a warm day

datalogger | October 10, 2017 | blog,Temperature,temperature logger,Temperature Loggers

It was autumn. It wasn’t too hot. The sun is shining, the birds are chirping. It’s a nice day.

And then my phone alarm starts going off. The car is hot. Way too hot…

The glass has turned my car into a sauna. Actually, it’s probably more like a steamer. Sit in there at the moment and you will be cooked.

It amazes me that people will still leave their kids or pets in a car and duck into the shops or a friend’s place. All it takes is for the sun to come out from behind a cloud and within minutes your car can turn into a furnace.

Hindsight won’t help South Australian Restaurants

datalogger | September 29, 2016 | Temperature

The storm may be over, but the effects of yesterday’s storms will be impacting South Australian restaurants.

Assuming the restaurant managed to avoid any damage, the owners are now walking into a facility that has been without power for many hours. That means that they have a fundamental question to answer –

Do you keep the food or throw it out?

Keeping it means that you have a potential food safety risk.

Throwing it out is a loss of income. There is also the issue of restocking, and with the entire supply chain compromised, it may be difficult to buy items.

The cost of the unknown

The majority of restaurant and cafe owners won’t have any option – they know there was an extended power failure and that their fridges and freezers were off. They know their fridges would have been over 5°C.

What they don’t know are:

  • When it started to go over 5°C
  • When it returned back under 5°C (or how long it was above 5°C)
  • How warm it actually became

And that information is critical. It isn’t essential to throw food out that has been over 5°C but it is essential to throw it out if it has been over 5°C for too long.

The only problem is that they don’t know how long it was over 5°. Because of this, they have no option but to dispose of the food.

The solution

The solution is quite simple – temperature loggers.

Temperature loggers record the date, time and temperature every couple of minutes. This would have meant that the restaurant owner or manager could have identified when the fridge started to get too warm, when it cooled down again, and if it was a significant problem.

They aren’t even that expensive. A restaurant would spend more on toner cartridges each year.

Forget about hindsight, what about tomorrow?

It is just a matter of time before there is another incident. It could be a big storm, a lazy cleaner who unplugs a fridge, a broken fridge, or just a disgruntled customer. Now is the time to add that extra bit of protection for your product and your reputation.

Contact us on 1300 30 33 34 to work out if temperature loggers are right for you, and what the best type is.

The Rotten Food Cookbook is Amazon Best Seller

datalogger | July 4, 2016 | The Rotten Food Cookbook

Last week we released the eBook version of The Rotten Food Cookbook on Amazon and we reached the Amazon Best Seller list.

The Rotten Food Cookbook is a parody cookbook we wrote to try and highlight major causes of food poisoning. It’s all about what people care about most (Food Poisoning) so that we can then talk about ways of avoiding it. As I say at the end, “no one care’s about food safety, but everyone cares about food poisoning”.

You can buy a eBook version from Amazon.

Amazon Best Seller

How often should you record the temperature of a commercial fridge?

datalogger | May 17, 2016 | Temperature Loggers

Recently we were asked:

When are you required (according to the food standards code of Australia and New Zealand) to take the temperature reading of a commercial Fridge, a commercial freezer and a Bain Marie that is set at 60 degrees and at what intervals e.g Every 2 hours or Twice every day ?

The simple answer is:

It depends

I would love to say it depends upon what is stored in the fridge, or the size of the fridge, or the type of facility but the truth is…

It depends 100% upon the person doing the inspection.

In some councils they don’t even ask for records. So the answer is “never”.

In many councils they just expect one or two a day. A good safe answer is “twice a day”.

As a business owner, however, this is a silly answer. It means that your staff have to find just two times each day when the fridge is within range. If they leave a fridge open they can close the door and come back 15 minutes later. That’s not peace of mind.

In the medical industry they used to record the minimum and maximum temperature once a day. What was great about this was the fact that the entire day was effectively monitored. If there was a spike in temperature then it was caught by the minimum or maximum. This meant that a single check, once a day, was able to confirm that everything was fine all day.

To ask staff to check the temperature twice a day and write down a single temperature is a token gesture. The standards are even written around the 2 hour / 4 hour rules. At the very least it should be every 2 hours.

A minimum/maximum thermometer should be the very least they are expected to use.

Of course I am going to recommend that they use a temperature logger. After all, it’s not the maximum temperature that is critical, but how long it has been above 5°. Only a temperature logger can provide an accurate portrayal of what has happened.

Food temperature danger zone explainer video

datalogger | May 12, 2016 | Uncategorized

What is the danger zone for food temperature?

It’s a very simple message, but critical to food safety. This short explainer video covers the food temperature danger zone and the obligations on restaurants and cafes.

It would be great if you shared the video with friends to help get the message out.

How To Configure Logtag Temperature Logger

datalogger | April 18, 2016 | How to guides

How To Configure Logtag Temperature Logger Video

This is a quick video explaining how to configure the logtag temperature logger for fridges including vaccine fridges and hospitality (food) fridges. A brief summary is also shown below the video.


Field Comments
UserID The User ID is a description field to help you identify the unit. It could be the name of the fridge, or the name of the company or practice.
Start Push button start means that you will need to push the “Start/Mark” button on the logtag when you want the logger to start.Push the button when you place it in the fridge.
Record Record reading continually means that you will always have the most recent readings in memory.If you use the other option then the logger will stop when the memory is full.
Sample rate “Record a reading every” is the sample rate. This is how often the Logtag will measure and store the temperature.For most applications a 5 minute sample rate is ideal.
Start delay There is generally no need to have a start delay, especially if the push button start is being used.
Green indicator Turn on the “Enable the OK (green) indicator. This is the LED on the Logtag that flashes green.
Alert indicator Turn on the alert (red) indicator so that it will alert you if the temperatures are too hot or cold.
Temperature limits For vaccine fridges set the low and high alarm limits to 2°C and 8°C. That is 2° and NOT -2°.For food fridges set the low and high alarm limits to 0°C and 5°C.
After Set this to 4 consecutive readings. This will minimise false alarms due to a short fluctuation in temperature. These spikes are typically caused by the door being left open or the fridge being restocked. They will not impact on the product being stored but will momentarily change the air temperature.
Clear and reset The “clear and reset alert” option allows the user to press the “Clear” button on the logger to stop it flashing red and start flashing green.If this is not turned on, the only way to clear the red flashing LED is to reprogram it with a computer.
Passwords Do not enter a password in the password fields, unless you specifically require the security feature.