Damp meters are they any good

Discussion in 'Motorhome Chat' started by chaser, Aug 27, 2014.

  1. chaser

    chaser Funster

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    Just posted this in another thread, but thought its worth one of its own, in case it's missed.

    Got the damp meter out yesterday, nearly had palpitations, shoved the probes under the rubber on the windows, every one went off the scale, so got the rubber off one , dry as a bone! So shoved the probes just in the rubber, off the scale, has anyone else found that the rubber reads soaking even though it's dry, never come across anyone saying that before, could have you ripping your van to bits for nothing
     
  2. movan

    movan Funster Life Member

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    Don't know about rubber, Chaser, but similar thing happened in my house. Ended up paying for a wall to be knocked down and rebuilt to be told the problem was from next door... :( ... Damp!!! The mere word gives me goosebumps. Hope you get rubber sorted.
     
  3. chaser

    chaser Funster

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    Perfectly dry rubber what else does it show wet when it isn't?
    image.jpg
     
  4. WOOOODENTOP

    WOOOODENTOP Funster

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    I use a dehumidifier from ALDI, run it for 3/4 hours at night on a timer , off the solar panel thru the inverter so costs me nothing and keeps the van nice and dry
    Woooody
     
  5. chaser

    chaser Funster

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    Yes but nothing is wet, it just says it is
     
  6. John Laidler

    John Laidler Funster

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    If dry rubber is reading high moisture then the rubber is conducting electricity, this is how these meters work. Rubber is a natural insulator so if it is conducting electricity then there is either some sort of additive in there or perhaps something on the surface like an adhesive. However, my guess would be the rubber is dry on the surface but has moisture inside it.
     
  7. tambo

    tambo Read Only Funster

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    Maybe it was your undergarments when it went off the scale :p

    Have to say I've a cheap one from ebay which seems to work okay it showed a 7% reading on my rear window and when I removed them all today to reseal there was signs of a leak in that window and the one above cooker .....my windows don't have those rubbers though it's the ones in frames

    Luckily there wasn't any damage and I've caught them in the nick of time :)
     
  8. GJH

    GJH Funster Life Member

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    The one I have can be set for different materials. Maybe they aren't designed for checking rubber?
     
  9. scotjimland

    scotjimland Funster Life Member

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    The rubber the window seal is made from probably has carbon black added (an excellent conductor) to make it UV stable.. hence the conductivity .. try your meter on a dry van tyre.. I bet it shows it's 'wet' ..

    don't press too hard.... :LOL:
     
    Last edited: Aug 27, 2014
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  10. chaser

    chaser Funster

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    Yeah you are right , but it doesn't show as much as the window rubber
     
  11. Gooney

    Gooney Funster

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    I bet it doesn't leave black streaks on your van like the rubber seals do either;)
     
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  12. Wildman

    Wildman Read Only Funster

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    a moisture meter is an electrical resistance meter nothing more, should be used for comparative readings of identical materials. Differences in readings at various places will show up a damp problem (note DIFFERANCES).
     
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  13. tonyidle

    tonyidle Funster

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    .
     
  14. movan

    movan Funster Life Member

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    . to you too! o_O
     
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  15. magicsurfbus

    magicsurfbus Funster

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    Always worth doing a battery check on the damp meter as well before use. Duff battery = weird readings, a bit like a multimeter.
     
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  16. Puddleduck

    Puddleduck Funster

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    A good working damp meter is worth it's weight in gold when used correctly.
     
  17. chaser

    chaser Funster

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    But when you get all these unusual findings you can't really trust one to spend tens of thousands
     
  18. Puddleduck

    Puddleduck Funster

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    As ScotJimLad said there will be an additive in the rubber which is an electrical conductor. Carbon black used to be used quite a bit in specialist paints. I'm not sure if it still is as it's over 30 years since I worked in the paint industry.
    What did the damp meter show elsewhere? Normal readings?
     
  19. chaser

    chaser Funster

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    Yes as I said in an earlier post I checked the wall under the window and it showed damp off the scale but the probes were touching the rubber didn't realise till I moved the rubber and checked underneath , dry as a bone , dry everywhere
     
  20. wivvy's dad

    wivvy's dad Read Only Funster

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    ALDI selling digital moisture meters for £12.99 from next Thursday 4 Sept
     
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