NOVA tank repair.

Discussion in 'Darkroom Equipment' started by fidget, Jul 9, 2008.

  1. fidget

    fidget Member

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    My 12x16 3 slot NOVA processing tank has some cracks deep within the middle slot. If I fill it with water some leaks into the heater void on each side (they are independent tanks). It got this way through being posted inadequately packed. I have made several repairs to it using glue supplied by NOVA, but these cracks are too deep to see.
    The middle tanks will hold the stop solution, so if it were to mix with the heater water, perhaps it would not be a problem.
    In a last ditch attempt to seal it before ditching it or trying it as is, I thought that I could fill it with something like say, varnish, them draining it and cleaning out what I could. If the varnish had seeped into the cracks, they could be sealed this way.

    Is a finish like varnish likely to be affected by stop solution?

    Any ideas for other suitable substances to flood the slot?

    Regards, Dave...
     
  2. Ian Grant

    Ian Grant Subscriber

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    Varnish would be a very temporary repair, it won't bond to the plastic properly and will soon leak again.

    You need to try running the correct solvent cement down each edge and along the bottom edges. I used to use a German two part solvent cement which I bought from the George Fischer stockist in Birmingham, this will bond a variety of different plastics and is extremely resistant. It stood up to boiling concentrated acids so stop-baths no problem. Can't remember what it was called.

    Ian
     
  3. bogeyes

    bogeyes Member

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    repair

    You could try mixing some fibreglass resin, coat the inside of the tank slot then lay in some fine fibre glass matting, you may need to repeat the process until you have applied two or three layers. Wait for each layer to dry before applying the next. The end result would be a completely relined tank.
     
  4. MikeSeb

    MikeSeb Member

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    Dave, in the US we have an epoxy 2-part adhesive/bond called "JB Weld". If it's available in the UK, it should do the job. Stuff'll patch/fill/stick to just about anything.
     
  5. fidget

    fidget Member

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    Thanks for your suggestions, I have the correct glue and have run this down the edges and along the bottom edge that has the leak. Part of the problem is that there is a crack away from the edge. Getting at it is very difficult, as the proverbial decorating the hallway through the letterbox.
     
  6. Dave Miller

    Dave Miller Member

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    I’m sure you have considered this, but it’s worth mentioning. The solvent may not work if the crack has moisture in it, this may be quite difficult to drive out, but storing the drained unit somewhere warm and dry like an airing cupboard for a week should do the trick.
     
  7. fidget

    fidget Member

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    Thanks Dave, you're right and it takes a great deal of time to dry out. Before my last glue run I had given up on it. It had been dry for weeks. Of course, all that will be spoiled when I test it, so I'm trying a few ideas whilst it is dry enough.
    One consideration is that if the water level in the heater void matches the level stop solution in the slot, there will be very little flow either way (I guess) so could be used provided I am absolutely sure that there is no leakage into the dev slot. It's quite a leak too, maybe 10cc in 20 mins when the heater void is empty.

    But if there is some flow of solution into the heater void, will it matter much? The heater elements may well be sheathed in glass so will not be unduly effected. I don't know if they are intact and may not use them anyway.
     
  8. glbeas

    glbeas Member

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    If there was some way to seal the top and apply one or two psi air pressure to it after the tank was run in with glue solvent it would drive the glue into the cracks and get a better seal when dry. If you have enough, pour an excess in and slosh around the sides to cover everything then pour it out.
     
  9. Dave Miller

    Dave Miller Member

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    I doubt that the stop solution getting into the water jacket will do much harm, but consider asking Nova that question, they may know different. Perhaps you may have to drain the water jacket when doing a spring clean, but I guess you would have to do that anyway.
     
  10. Neil Souch

    Neil Souch Subscriber

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    Hi,
    I agree entirely about with Dave's recommendation of getting the tank dry first. I have used Nova's glue to repair one of my tanks and it worked fine (and has lasted) but it was easy to get at as it was on the outside. If I were tackling your repair I think I would be tempted to get a sharp tool inside and open up the crack a tad to ensure the glue entered the crack. Also do it in two goes - first fill the widened crack and later when that is dry try to float some more glue over the repair. I appreciate seeing what you are doing, access and finding the tools to do this will be difficult but if you could overcome these problems the repair would probably last. Maybe a broken hacksaw blade would make a crack opening tool and could also be used to apply the glue - just a thought.

    Cheers,
    Neil.
     
  11. fidget

    fidget Member

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    Thanks for your ideas. The cracks may be extensive and are very...very difficult to access. It's not a practical concern at the moment. I did consider sawing it in half along the middle slot, repairing the cracks and then glueing it together again, but dismissed this as silly.
    I like Gary's suggestion of applying mild air pressure to the varnish inside. If I clean out the unused varnish, there may be no limit to the number of times I can run the exercise. Yup, either that or Radweld.

    I'll have a go.

    Dave...
     
  12. Neil Souch

    Neil Souch Subscriber

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    Hi,
    If the varnish doesn't work how about putting in a liner such as a suitably sized poly bag? This may not be a lasting repair but it would keep the tank going for a while longer and would be a cheap / easy option to repeat when required.
    Cheers,
    Neil.