# If the value is below a reference value for more than x hours, then do something "fail-safe"

**URL:** https://discourse.nodered.org/t/if-the-value-is-below-a-reference-value-for-more-than-x-hours-then-do-something-fail-safe/65819
**Category:** General
**Created:** [30 July 2022 17:50 UTC](https://discourse.nodered.org/t/if-the-value-is-below-a-reference-value-for-more-than-x-hours-then-do-something-fail-safe/65819 "2022-07-30T17:50:35Z")
**Posts on this page:** 1
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### Author: ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [30 July 2022 19:49 UTC](https://discourse.nodered.org/t/if-the-value-is-below-a-reference-value-for-more-than-x-hours-then-do-something-fail-safe/65819/5 "2022-07-30T19:49:34Z")

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> [@A guide to understanding 'Persistent Context'](https://discourse.nodered.org/t/a-guide-to-understanding-persistent-context/4115):
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> This is something I wrote up after playing with the context options. I've filed a PR with some of this added to the Node-RED documentation but thought I'd release it here also. I hope people find it useful. Paul A guide to understanding 'Persistent Context' Prior to Node-RED v0.19.0, data could be stored in context as a global, flow or node. This was stored in memory and would be reset with a restart of Node-RED. As of v.0.19.0 you can now store node, flow and global context data in memory O…

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