67 Signs and Causes of Equipment Malfunction
Learning Objectives
Identify signs and isolate causes of malfunction and list corrective actions.
A sign AND cause of equipment malfunction is miscalibration.
Calibration
Using measuring equipment to measure something of known value to see if the measuring equipment is accurate.
Calibration Needs in a Food Plant:
- All equipment and instruments used for ensuring safety, quality, sanitation, and regulatory compliance must be calibrated.
- Calibration ensures the equipment readings are accurate and give control of the process.
- Can contract with the external supplier or conduct in-house
- Needs to have in-house support and management even if contracted.
To achieve this:
- Develop effective procedures for calibration
- Document the procedures in SOPs
- Maintain records of calibration activities, including corrective actions
- Verify to ensure that procedures are being followed
- Put someone in charge
The following is an example SOP documenting the procedure of calibrating a scale. This document is accessible at:
PROCEDURE FOR CALIBRATING, STANDARDIZING, OR CHECKING EQUIPMENT
Revised 06/16
PROCEDURE #46
Equipment Checked: Scales (Balances)
Reference Documents: NIST Handbook 44, AASHTO M231, ASTM E617, ASTM C138
Purpose: To provide instructions for checking the accuracy of scales to be used in area and project labs. All scales shall be checked annually.
Inspection Equipment: Suggested standard weights (checked against calibrated scale) 100g, 200g, 5kg, 10kg, 20kg.
Tolerance: The allowable tolerance throughout the range checked shall be equal to or less than 0.1% of the test load. The allowable tolerance for Platform scales used to determine fresh concrete unit weight shall be equal to or less than 0.3% of the test load.
Procedure:
- Set up the scale in a location away from drafts or excessive air movement.
- Level the scale, and if weighing underwater, observe that the apparatus is free of any obstruction that may affect its movement.
- Perform Span Check:
Place the verification weights in the center of the scale. Record the weight to the readability of the scale.
Confirm repeatability by placing one of the weights on the scale a second time to obtain the same weight. Confirm that the reading returns to zero when the weights are removed.
- For weighing devices with a capacity of up to 1,000 grams, the suggested verification weights are 100g and 200g. External scale calibration weight shall be 200g.
- For 12kg weighing devices, suggested verification weights of 5kg and 10kg. External scale calibration weight shall be 10kg.
- For 30kg weighing devices, suggested verification weights of 10kg, and 20kg. External scale calibration weight shall be 20kg.
- For platform weighing devices used for standard density determination, the suggested verification weights are 10kg and 20kg.
Note: It is desirable to perform additional checks on scales for accuracy after they have been installed in the construction field lab.