What are alert , action and acceptance limit?

Alert limit, action limit and acceptance limits play very important role in different testing. Alert and action limits are defined to have better control on the system or process. 

Alert Limit: Alert limits are defined to check any change in the results as per trend data. Basically alert limits provide alert when results are crossing specific threshold. If results are higher than alert limit, it mandatorily not required any action but taking controlled measures at alert limit can control any future failure.  

Action Limit: Action limits are defined to prevent the any system failure. Action limits are the limits which when crossed required action. If specific action not taken then limits can pass the acceptance limits which leads to failure of the process.

Acceptance limits: Acceptance limits are defined as final limits. These limits when crossed results in system failure and operations needs to be stopped.

Alert, action and acceptance limits are defined to control any process. For example in case of purified water. The microbial acceptance limit of purified water is 100 cfu per mL. If we get results higher than 100 cfu per mL then water system needs to be shut down because purified water is used in the cleaning of equipment, manufacturing of pharmaceutical products etc.. Contaminated water can contaminate the product. So, alert and action limits shall be defined to have better control on the system and process. Alert and action limits shall be defined based on the trend data.

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