[PSUBS-MAILIST] Pressure change indicator?

[Cliff Redus via Personal_Submersibles]

Lasse,
It would be very straight forward to build your own depth
measuring and display system that could also tell you if your are going up or
downs.  The parts would be a simple PLC
with at least one analog input channel, a 0-10 vdc pressure transmitter to measure ambient water pressure and
inexpensive display.  Ladder logic would
be easy to right as all you are doing calculating depth as a function of
pressure and density.  Again simple
calculation in PLC to determine if you are ascending or decending based on pressure
change i.e, if ambient pressure is increasing, you are descending and
descreaing, you are ascending.
	1. Cheap PLC ($129) http://www.automationdirect.com/adc/Shopping/Catalog/Programmable_Controllers/CLICK_Series_PLCs_(Stackable_Micro_Brick)/PLC_Units/C0-02DD2-D
	2. Cheap pressure transmitter ($125) http://www.automationdirect.com/adc/Shopping/Catalog/Sensors_-z-_Encoders/Pressure_Sensors/Pressure_Transmitters/Ceramic_Sensing_Element_-_M12_Cable_Connection/PTD25-10-0200H
	3. Cheap display ($161) http://www.automationdirect.com/adc/Shopping/Catalog/Operator_Interfaces/C-more_Micro-Graphic_Panels/3_inch_Panels_-a-_Accessories/EA1-S3ML-N
	4. Cheap software ($0) to program the PLC http://www.automationdirect.com/adc/Shopping/Catalog/Programmable_Controllers/CLICK_Series_PLCs_(Stackable_Micro_Brick)/PLC_Units/C0-00DR-D
 
and Display http://support.automationdirect.com/products/cmoremicro.html
 
	5. Total cost $415
 
	6. Of course if you already had a PLC for boat
systems, then all you would need is pressure transmitter and a bit of ladder logic programming.
	7. Finally, you can always go old school install a manual
depth gage http://www.weksler-gauges.com/pdf/p22.pdf


Cliff

 
 From: Lasse Schmidt via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Friday, September 19, 2014 4:18 AM
Subject: [PSUBS-MAILIST] Pressure change indicator?
  

Hi,

I´m interested in finding two instruments, I hope I can get some pointers from you guys.
First of all, i´d like to find an instrument that shows if the sub is rising or descending, like the ones found in airplane (variometer). I have googled  and googled but can´t find anything.
Does anyone have any suggestions how i can see (with an instrument) if the sub is stationary or moving up and down?

Secondly, I´m looking for a digital solution to show my passengers how deep we are (or what pressure is outside), I have been told that there are such instruments but could´t find any.

All pointers and suggestions to specific products is appreciated.
Below is a news coverage about our sub, made by swedish television.
http://www.tv4.se/nyhetsmorgon/klipp/maria-forsblom-pr%C3%B6var-livet-under-ytan-2784847


Cheers, Lasse


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