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David Brown
08/21/12 17:39
Read: 1235 times
Klamath Falls Oregon

#188109 - Designing a product for use in water
Hey all,

I know this probably isn't the best place to post this, but I do know that the active members here are incredibly intelligent and have years of experience. If this isn't appropriate, please feel free to delete this thread. I also realize this could develop more into paid consulting, which I'm also open to. I just haven't come across a forum that has a similar level of expertise :)

Anyways, I have been tasked with developing a system that will utilize a touchscreen/knob combination that the user will use while they are standing in a swimming pool. The display will be mounted to a frame, with several low voltage/current cables in a conduit going between it and the rest of the system. Everything in the electrical room, and by extension the display, will be on GFI breakers. The unit will likely run on 24vDC, and the highest voltage internally would be for the displays' LED backlight, at ~30vDC.

I've designed a system (on paper) that would work great - out of the water. I'm just apprehensive about throwing a user in front of it while they're standing in a swimming pool without having the design looked over by a more experienced set of eyes.

The interface itself would consist of a plastic enclosure, the touch panel, and the knob. Internally there would be the display and the processor board. The touchpanel is rugged and designed to be water resistant [link]. The outside edge of the touch panel would be sealed to the enclosure. The knob is a sealed potentiometer, and would be a basic 3.3v voltage divider to get position. The conduit connection would also be sealed.

I guess I'm curious to know if there are published standards/tips I should follow when finalizing this design. I've done some research, but haven't found much at all. I just need to ensure that nothing bad will happen, even if the display itself falls in the water. Or, is it as simple as sealing the touchpanel, having a good connection to ground from the panel, and a GFI breaker? Should the analog lines to the touchpanel and knob be isolated? etc.

I also looked a bit at some off the shelf industrial automation displays/systems, but I have the same concerns about them before throwing a user in front of them.

Any advice would be greatly appreciated,

"The more I learn, the more I discover I didn't know."

List of 22 messages in thread
Designing a product for use in water      David Brown      08/21/12 17:39      
   Have you considered silicone coating?      Richard Erlacher      08/21/12 21:11      
   one link      Stefan KAnev      08/21/12 22:04      
   Waterproof enclosures      Oliver Sedlacek      08/22/12 02:12      
      Projective touch - or maybe waterproof tablet      Per Westermark      08/22/12 06:27      
         If that potentiometer wasn't a hard requirement      Erik Malund      08/22/12 08:00      
            more details      David Brown      08/22/12 10:54      
               You might want to look into that a bit further      Richard Erlacher      08/22/12 13:33      
                  buttons for up/down gives tactile feedback      Per Westermark      08/22/12 14:12      
                     nevertheless, a strobe wheel rather than a pot ...      Richard Erlacher      08/22/12 15:24      
                        more good ideas      David Brown      08/22/12 16:42      
   Go to the lowest practical voltage      Jim Granville      08/22/12 16:20      
      answers      David Brown      08/22/12 17:39      
         Electric shock and intrinsically safe      Oliver Sedlacek      08/23/12 02:11      
            Isolators      David Brown      08/23/12 19:13      
               a question and a reference      Erik Malund      08/24/12 07:05      
                  answers      David Brown      08/24/12 10:55      
                     tethered unit??      Erik Malund      08/24/12 12:12      
                        mounted display      David Brown      08/24/12 12:32      
                           have you considered a combination of battery and solar?      Richard Erlacher      08/24/12 14:56      
                              indoor pool      David Brown      08/27/12 10:24      
                           Wireless chargers      Oliver Sedlacek      08/27/12 15:30      

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