What are Chart Recorders?
A chart recorder is an electromechanical instrument that records an electrical or mechanical input trend onto a piece of paper (the chart). Chart recorders may record several inputs using different colour pens and may record onto strip charts or circular charts.
This instrument records various process and electrical signals. The most traditional chart recorders record data on paper. The paper is passed under a pen and the pen is deflected in proportion to the signal. The result is a graph or chart of the data. Chart recorders are available in single or multichannel styles (single or multi-pen) and in various configurations. Many of today's chart recorders can also record information in a digital format for download to a computer.
There are various data recorder models available. Recently, conventional analogue chart recorders have combined with data loggers, and PC-based functions have been added.
Typical Uses of Chart Recorders
Chart recorders are found in manufacturing plants, where they track such variables as:
• Temperature
• Pressure
• Flow
• pH
• humidity
Laboratories use them to monitor scientific and engineering data generated in testing:
• Diagnostics
• Statistical analysis
• Work requiring a graphic record
Types of chart recorders
• Strip Chart Recorders – consists of strip of paper passed beneath one or more pens. Popular in laboratories and process measurement applications, suited for recording continuous processes
• Circular Chart Recorders – records data in a circular way, ideal for batch processes where a set process time is known.
• XY Recorders - accept two inputs and create a graph of one input versus the other. Commonly used to determine the relationship between the two inputs. For example in a chemical process, an XY recorder might be used to monitor the effect temperature has on the pressure of the process.
• Hybrid Recorders – act as a recorder or data logger
• Paperless Recorders – displays the chart on the recorder’s graphic display, data can be recorded onto a memory card for later transfer to a computer
Help choosing one, consider the following
• How many/types of inputs need to be recorded?
• Do different input types need to be recorded in the same unit?
• What type of recording is required?
• Communication interface required?
• Bench style or panel mounting?
• Is message printing required?
• Is the recorder to perform alarm functions?
• How many set points per channel?