For most technicians, calibrating switches becomes somewhat of an afterthought. This might be due to the fact that switches are commonly viewed as an over-simplistic device. A technician may see a switch and think, “What is there to calibrate?” The fact of the matter is there are significant reasons to calibrate switches and multiple ways of doing so.
The three main reasons to calibrate switches:
- Due to regulations from the FDA, EPA or EMEA all regulated instruments, including safety instrumented systems (SIS), require calibration and documentation.
- A faulty switch can be a safety hazard for both employees and customers. If too much pressure builds up in a vessel and the switch is not releasing properly it could explode and seriously injure nearby employees and cause damage to the surrounding factory. For industries producing consumable items, a faulty switch leads to product quality issues. This type of inconsistency in ingredients can prove fatal when dealing with medication or food products.
- A switch that is not functioning properly and is opening and emptying out at the incorrect time wastes material. Ultimately this causes a factory to lose time and money, whether it is due to the cost of raw materials, failing an audit or recalling a product.
With all of these reasons to calibrate, why is it still an afterthought? Maybe it is not an issue of why one calibrates a switch, but how and what is involved?
There is what we like to call the shade tree mechanic way. Here a technician applies pressure and hooks up a meter to the switch and waits until the meter changes. At this point the technician sees the meter change and maybe hears it click and looks at the dial and tries to guess at what pressure the switch tripped. (Not so scientific).
Calibration Resource List
How Often Do Measurements Need to Be Calibrated?
Just in Time, or Just Too Late? A Kaizen Approach to Calibration
How to Improve Industrial Productivity with Loop Calibration
Temperature Calibration: Using a Dry Block to Calculate Total Uncertainty
How Can Advanced Calibration Strategies Improve Control Performance?
How to Calibrate a Pressure Transmitter
Uncertainty in Calibration
Calibration Uncertainty and Why Technicians Need to Understand It
How to Avoid the Most Common Mistakes in Field Calibration
Learn Advanced Techniques in Field Calibration
How to Build an Industrial Calibration System Business Case
How to Use Calibration Tools for Accurate Process Temperature Measurement
How Does Low Flow Affect Differential Pressure Flowmeter Calibration?
Three Common Pitfalls of Pressure Calibration
How to Calibrate Differential Pressure Flowmeters
ISA Industrial Calibration Worksheets
Measurement Uncertainty Analysis Excel template plus book excerpt
Calibration Handbook of Measuring Instruments book excerpt
In-Depth Guide to Calibration for the Process Industries eBook
Calibration Uncertainty for Non-Mathematicians white paper