10 QUICK TIPS ABOUT CALORIMETERS
There is no doubt that bomb calorimeters are the most valuable instrument in a laboratory. Almost every aspect in our present lives have been shaped or influenced by the energy reading of a calorimeter, yet most people don't even know about it.
But don't be fooled, there are calorimeters and there are CALORIMETERS. Some are cheap and others are expensive. So, how do you choose which one is the right calorimeter for your laboratory?
CALORIMETER SIZE AND SPACE REQUIREMENTS
Most laboratories are not very big and space is at a premium. Some calorimeters require above counter and below counter space, which become a challenge to accommodate. Other calorimeters are just above counter, but take up 2 square meters. Our yellow DDS Oxygen Bomb Calorimeters take up as much space as any two average laptops.
CALORIMETER BOOT UP AND REPETITIVE SPEED
There are two considerations to speed. The first point to consider is the time it takes to boot up and get ready for the first determination. Some calorimeters are ready to use in seconds and others require a few minutes to an hour. There are even some that you shouldn't switch off as it just takes too long to start up again. Having the calorimeter ready to use when you need to use it is important, but be aware that having some power hungry calorimeters left on indefinitely will influence your long term running cost.
The second point to consider is the actual repetitive speed of the calorimeter. Again, this will vary from machine to machine. In most instances, the repetitive speed is proportional to the price of the calorimeter. The repetitive speed of a bomb calorimeter system is typically governed by three factors :
- The time is requires for the calorimeter system to stabilize and no longer be influenced by the outside environment.
- The time required after firing the sample inside the bomb vessel to calculate the energy of the sample.
- The time required to cool down the bomb vessel so that it can be used again.
The repetitive speed of the bomb calorimeters vary from 14 samples per hour to 1 sample per hour. Some calorimeters will give you a burst of 2-3 CVs first thing in the morning.
In most cases when purchasing a calorimeter this point is often overlooked. You might understand the basic operation of the calorimeter, but does your operator? How many operators will be using the calorimeter and who will give support when something goes wrong during the graveyard shift? Operational manuals are key and so are training videos, but they are typically not available when the operator has a problem. The more modern calorimeter have help manuals and support messages that guide the operator into solving the problem himself. The better calorimeter are just intuitive to operate, automatically providing information in the background to best facilitate a flawless determination.
The bomb calorimeter segment is growing and new manufacturers are always coming on board. The only way to differentiate between the good and the bad is to look at their track record, how long they have been manufacturing calorimeters, how many models do they have and finally what are other people on the internet saying about them.
Most calorimeter manufacturers don't specify the overall operating cost to having a calorimeter in your laboratory. Almost all calorimeters require an air-conditioned environment to operate and then some calorimeters use 1500W of electricity. Our CAL3K range of calorimeters require no air-conditioning and use an average of 14W of electricity.
CALORIMETER WATER REQUIREMENTS
Typically older calorimeters use water to cool the vessel down and to provide an insulation barrier. These types of calorimeters are difficult to set up in a laboratory, as you need a water supply and water drainage, making them very difficult to move around later. Our modern calorimeters don't use water, so that is another operating cost saving.
LIFE EXPECTANCY OF A CALORIMETER
With the amount of money that some of these calorimeters cost, you expect them to last a lifetime, but will they? The life of a calorimeter is largely dependent on the quality of manufacture, the cleanliness of the lab environment, operator training or intuitive operation and regular servicing. With that said, our calorimeters are designed to be abused and will still give an average 10 year life span in the absolute worst conditions.
Automation has a different meaning to different manufacturers, hence making the purchasing a challenge. Some calorimeters provide the energy answer automatically during the determination and others automatically increment the sample ID to the next available number. Others offer automatic oxygen filling, automatic de-filling, automatic lid opening, automatic firing, and so on. Unfortunately there is no shortcut, engage with the manufacturer and understand how you want the calorimeter to operate.
How do you get the results or temperature reading or event log, or parameters out of the calorimeter? What type of output ports does calorimeters have and how do you connect to them? Again it will depend on your laboratory environment. If you have high interference due to heavy machinery, then most wireless options are not for you. Depending on your environment, you will need to shop around to establish the best communication medium that will work for you. Sending Result Data automatically when the sample is complete could also be a requirement for LIMS or real time management. USB, RS232 and Wireless all have their strengths and weaknesses, but we would look for a calorimeter which offers all three. Between these three interfaces, all your laboratory needs will be fulfilled. Should your laboratory move one day, then you have the ability to use another type of connection and not be limited to just one.
There is more to repeatability than what is stated on the specification sheet of a calorimeter. The older calorimeters with a poor repeatability of 0.5% RSD did not have the problem that the modern more accurate calorimeters have. Some calorimeters can achieve a high 0.05% RSD, but impossible to simulate in a normal laboratory. At this accuracy your sample preparation is critical, handling of the bomb vessel is critical, handling of the crucible is critical and your operator needs to be meticulous in his procedure. Even the soap you use to wash your hands plays a part. It is therefore more realistic to achieve a 0.1% RSD in most modern calorimeters that can be achieved in most laboratories. Consistent sample preparation techniques are far more important in achieving a repeatable RSD than a walk-on-water calorimeter.