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Old 05-15-2015, 05:04 PM   #64
Former Vendor
Member#: 110029
Join Date: Mar 2006
Location: Sussex, England
2004 Citroen Picasso


Originally Posted by JMlegacy View Post
Great thread Richard.

I'm interested in a DIY abnormal pressure detection failsafe

pressure too low > trip relay for failsafe
pressure too high > trip relay for failsafe

thing is, i don't know what device i can use for this. I'd much rather NOT use two hobbs switches for this.

Isn't there some device like a digital pressure sensor that can set two pressure points and trips if pressure is outside of this range?
I'd install the pick up at the nozzle
Originally Posted by JMlegacy View Post
also, for boost threshold/trigger point, what switch can I use for that since the hobbs may not be suited to the high temps of engine bay?
This set up should work well for a "single point" spray system where operational pressure is clearly defined. You can use an electronic pressure sensor but you need to build a high/low comparator circuit to make sensor of it.

Mechanical Pressure switch is prone to drift over time in the engine bay environment and seasons.
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