Observatory Weather Problems

[Gina]

Blowed if I can find where they say not to run them dry, James   But I definitely want a DC version not mains powered.

[JamesF]

Blowed if I can find where they say not to run them dry, James   But I definitely want a DC version not mains powered.

I can't find it now   I was definitely looking at the text before lunch though, and it wasn't for the pump that I linked to.  Ah well, I guess it's academic now.

Another possibility if the water is a little dirty is a magnetically coupled impeller pump.  They should be tolerant of small bits of detritus in the water.  I have this one, again for use in the brewery, but I think the requirement to be food safe at 100C and having stainless fittings makes it rather more expensive than a similar model to suit your needs ought to be.

https://www.brewbuilder.co.uk/ts5-mini-mag-pump.html

James

[Gina]

Thanks James   However, I've dedided to try your previous suggestion and have ordered one plus extra for 1st class post - should come Friday.  Also ordered some PVC pipe for it as the stuff I've got is only 6mm ID.  I might have a play making my own pump in the meantime - several on Thingiverse - main problem may be the pump - I have several but not sure any of them are suitable.  Could use a stepper motor I suppose but I think that's overkill

[Physopto]

Hi Gina have a look at these. You can leave them in the obsy in the dry and just use a suction hose with filter on the end down into the sump. Very easy to lift the hose and filter out to clean.

http://tfpumps.com/flojet_pumps/product/flojet-rlf122202d-self-priming-diaphragm-pump-12-volt-d-c/?gclid=CPLT09rJuMoCFcSVGwodoLEDXA

They are meant for clean water in caravans or motorhomes and such. A fine filter just before the pump can be used to protect the pump. They can run dry normally with out any detrimental effects.

Derek

[Gina]

Thank you Derek but that's too much for me.

[Gina]

I've screwed the new pump to an odd bit of hardwood and put it in the hole.  The float is probably some 50mm above the previous level and I have weighted the wood down with rocks.  I've put the 4m lemgth of proper bilge pump hose on it and that reaches right out past the end of the warm room and out over the bank into my neighbour's field.  I can see the end of it from the house so when we next get heavy rain I'll be able to see the outflow   I hope to get back to the instrumentation soom but the 1-wire device coding has been doing my head in and I need a rest from it.

[Physopto]

You can get similar on Ebay. Chinese one for about £10 or  £15 to try if you want. Just thought to muddy the water so to speak.