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Old 05-15-2015, 05:04 PM   #64
Aquamist
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Join Date: Mar 2006
Location: Sussex, England
Vehicle:
2004 Citroen Picasso
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Quote:
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
Quote:
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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