There are several styles of chart recorder units available –
From disk and strip recorders to electronic and multi-function recorders with data storage and communications ports. They all help to provide evidence that the required temperature was maintained as expected for the process in hand.
Special Build clean room incubator ( as illustrated above) was fitted with a multi-channel chart recorder to customer specifications and requirements.
In our experience we have found that for most laboratory incubation applications between -100°C and +75°C a disk chart recorder is acceptable. These are available in several factory set temperature ranges with disk rotation set at 24 hours or 7 days for one rotation.
For general purpose laboratory ovens there are some circular chart recorders are available with an extended range up to 500°C and above. Some disk chart recorders of this type also have high and low alarm functions built in so making them more suitable to verifying process control applications where temperature deviation is important. Disk chart recorders are usually built into the fascia control panel of the incubator or oven but can be supplied loose for wall fixing if preferred. This makes disk chart recorders a good general starting point for many applications.
JIM Engineering does not recommend Z-fold or similar style paper recorders for use with its ovens because it is impossible to look at historical information without removing the paper, checking it and then replacing the paper back in the recorder. This is fiddly and wastes time when ‘instant’ information is what is required.
Many more customers are now specifying that temperature information is stored electronically because it takes little space and can be retrieved and searched quickly.
This is often evidenced as there are many applications in the automotive, aeronautical and other critical industrial areas that require recorders to give absolute proof of temperature maintenance over long periods of time. Models with data storage and retrieval facilities are therefore an essential tool for these industries. Electronically stored data should be able to be retrieved using an SD card, Ethernet port, etc or displayed on the integral screen, analysed remotely and sent to other users worldwide with ease. This article primarily refers to the Nanodac range which is the market leader in electronically stored data chart recorders, which is why we use them.
We have fitted Nanodac electronic recorders from Eurotherm with great success. Using the full colour display screen and the on-line tools facility it is possible to fully programme the unit to suit the requirements of almost any user. The Nanodac is typically set up to be a multi-channel recorder with data logging but it can additionally be used as the main PID temperature controller for the oven. Multi-step programming of ramp and dwell cycles over prolonged periods is easy. The Nanodac is so good that it meets or exceeds the requirements for AMS2750D (NADCAP) surveillance and when fitted to the quality of JIM Engineering ovens the combination is such that NADCAP Class 1 temperature performance specification, or better, is now standard.
As costs have come tumbling down wire-free temperature loggers with alarm and data storage functions make complete sense. Stored information can be exported as csv files for printing and using in reports, etc. Temperature probes for anything from liquid nitrogen tanks to 850°C ovens are available. On-screen graphics show temperature trends in real time and if the cloud based system is used all this can be seen just by logging in to the secure servers from anywhere in the world. The cost of such a system is often lower than a more conventional multi-channel chart recorder.