Part of a Good Laboratory Program (GLP) is to calibrate/verify each piece of Lab Test Equipment that is used to test production material each day at start up before use. For example, this could include Laboratory Scales, pH Meters, ATP Test Units, Refractometers, Salt Analyzers, etc.... Many pieces of equipment come with their own "Calibration Standard" that should be used for this purpose. The method for Calibration should be outlined in detail in the User Manual from the Manufacturer for each specific piece of equipment.
On the other hand, if a piece of equipment is Certified/Calibrated Annually by an outside company (Scales for example), they should still be "verified" each day by the Technician before being used by using a "Certified Weight". Thermometers used for measuring a CCP in production are typically calibrated "weekly" unless they have been dropped, etc.. (as this is acceptable by both the USDA/FDA in HACCP Plans).
In Production, all production scales that are used for "weighing" purposes should also be "verified" each day before use as well. If a scale is used on a packaging line to monitor weight control, it must be checked/verified (and documented) first each day before it is used for this purpose to make sure that is is operating correctly before production begins.
It is important to make a complete list of all Equipment/Devices that are used in a Manufacturing Operation and identify the frequency in which "Calibration" and "Verification" is to occur. This list would include not only the Laboratory Test Equipment but also Production Equipment such as Water & Liquid Ingredient Meters, Load Cells (for Kettles, Holding Tanks, etc...), and so on.
Thank you.