The chances of a saturated Weston cell arriving as specified are...? - Page 1
Forum section: electronics / general

author: tggzzz
author_rank: Super Contributor
timestamp: March 26, 2017, 03:04:24 pm
content: http://www.ebay.co.uk/itm/272599548323Is itreally"new" in ebay terms?Will the shippers knowingly accept mercury and cadmium in a glass envelope?Will the shippers ensure it is kept upright?Answers in not more than two letters, please.

author: Vgkid
author_rank: Super Contributor
timestamp: March 26, 2017, 03:40:59 pm
content: Raises handNo!

author: Ian.M
author_rank: Super Contributor
timestamp: March 26, 2017, 04:49:17 pm
content: Click & collect from your local Argos!I wonder how long they'll be closed for the emergency HazMat contractors to decontaminate the store?Of course it is possible to ship something like this - when appropriately packed with a robust leakproof inner container foamed in place in a large box, strapped down on a pallet to make idiots think twice about tossing it around or tipping it, using specialist couriers with chemical handlng experience, but you certainly cant send it by post for £6.50

author: guenthert
author_rank: Frequent Contributor
timestamp: March 26, 2017, 05:11:26 pm
content: The link goes to a 'cadmium cell', there is no mentioning in the description or visible in the pictures that it would be a saturated one. There are no instructions visible in the picture that it needs to be kept upright, so I think it's a fair assumption that it is indeed an unsaturated one (which seem to be more common).I trust there C. Hoffman's judgement and think those are chiefly of interest for the steam punk crowd (or the subset thereof which doesn't mind toxic materials around the house), rather than the voltnuts.

author: tggzzz
author_rank: Super Contributor
timestamp: March 26, 2017, 05:57:17 pm
content: Quote from: guenthert on March 26, 2017, 05:11:26 pmThe specified temperature coefficient (40ppm/C) matches a saturated cell, not an unsaturated cell.QuoteIndeed.But it states "Condition: New: A brand-new, unused, unopened andundamageditem in original retail packaging (where packaging is applicable)", my emphasis. That means the voltage should be correct.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: March 26, 2017, 07:35:55 pm
content: I still feel bad about getting rid of so many standard cells, but their day has passed. Given that the one above has a bite out of the side, you have to wonder if the glass is even intact. Saturated cells are near to useless unless ovenized, so I'd be surprised if it was saturated. Coming in late as I couldn't limit myself to just "no!"

author: tggzzz
author_rank: Super Contributor
timestamp: March 26, 2017, 07:45:59 pm
content: Quote from: Conrad Hoffman on March 26, 2017, 07:35:55 pmOften the journey is more interesting than the destination.I'm fond of them because I used them at school (early 70s) when we needed to measure voltage mdoerate accurately, and they arepretty. We need pretty things in our life.Beyond that, my Weston cell has less noise than my (zener) Trancells. That's helpful when ressurecting a Solartron 7081.

author: Assafl
author_rank: Frequent Contributor
timestamp: March 27, 2017, 07:48:22 am
content: Depending on the type of cell they may not have to be transported upright. The Muirhead I have lay on its side probably for years - but has what Muirhead called a "sintered septa" - a seal which prevents the chemistry from escaping the relevant legs (unlike the NIST ones which did not have a seal and therefore the chemicals would mix if tilted or laid on side).As for the chemicals - as long as they are sealed in glass I don't see the worry. Also - in regards to the environment - If you can squeeze a few more (or a lot more) years from them - isn't it better than disposing of it (even at a a hazardous waste processor) and having the mercury find its way to the dumps and water supply and the air?

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: March 27, 2017, 01:23:12 pm
content: Mercury goes to a speciallized mercury recycler, so I'm not too worried about that. I don't know about elsewhere, but it's been illegal to manufacture standard cells here for decades. With a few lucky exceptions, almost all the un-saturated cells you can find are no longer stable. All my Eppley 100 series cells were pretty good when I got them, were treated very well, but eventually became unstable due to age. There's no stopping it, unlike saturated cells that can last for a lifetime or longer. Now, I did keep the aluminum and copper lagged Eppley and Weston enclosures, as I think the Weston in particular is a work of art. Eventually I'll put solid state references in them, powered from a wall wart jack on the back.

author: tggzzz
author_rank: Super Contributor
timestamp: March 27, 2017, 03:04:10 pm
content: Quote from: Assafl on March 27, 2017, 07:48:22 amOne of my saturated standard cells (from Cambridge Instruments) has sintered septa. When I received it, most of one had moved away from the electrode at the bottom. A judicious shake and it moved down again; the voltage is still reasonable, if slightly lower than the other ones.QuoteI don't disagree, but your points aren't really relevant. The key issues are:local laws about sale and purchase of mercury (which vary considerably)what happens if the local authorities find a spillage of mercury (ditto)if there is a spillage in transit, are the workers exposedwhether a courier permits/prohibits shipping something that could harm their workers

author: Assafl
author_rank: Frequent Contributor
timestamp: March 27, 2017, 05:09:41 pm
content: Quote from: tggzzz on March 27, 2017, 03:04:10 pmAgree to all points. I am not suggesting breaking the law shipping them (albeit they may not notice). I found mine at a local scrapyard and took it home and it is pampered on a bookshelf securely behind books. But they are already manufactured. So they can have a second life before they get to the recycler and become industrial waste.And it have seems to be very stable: which is loads of fun to measure since it is proving hard to get rid of uV level instabilities in the setup.

author: tggzzz
author_rank: Super Contributor
timestamp: March 27, 2017, 05:20:04 pm
content: Quote from: Assafl on March 27, 2017, 05:09:41 pmVery much so!QuoteI can use my saturated cell as a thermometer, but it does have lower "high" frequency noise than my zener-based sources. Since my voltmeter takes 50s for one high resolution measurement, in this context "high" is <0.1Hz

author: Vgkid
author_rank: Super Contributor
timestamp: March 28, 2017, 12:55:43 am
content: ^^^^Solartron 7081 possibly.

author: tggzzz
author_rank: Super Contributor
timestamp: March 28, 2017, 08:13:23 am
content: Quote from: Vgkid on March 28, 2017, 12:55:43 amYup.