Vintage weston element is it any good?

[dzseki]

I am not a voltnut, but at work a colleague of mine (a mechanical engineer) brought in a weston cell (Elektro Weida - Weltor, made in GDR)  that was his late father's. This cell is vintage, build date ~1962. Obviously is not holding the original voltage of 1.018xxx V instead it is showing 1.014xxx V with a calibrated HP 3478A multimeter, is there any use for the cell still, or is it just a paperweight?

[tggzzz]

I have a saturated cell from '49 that is still OK. I was lucky, since they are mechanically fragile (both glass and the electrode structure) and electrically fragile (zero current must be taken in use).

Unfortunately it looks like yours isn't useful any more, and is merely a toxic paperweight due to the visible mercury and cadmium salts in the solution. But I'd wait for comments from others before taking it for safe disposal.

[dietert1]

All you want to know about Weston cells: https://www.conradhoffman.com/stdcell.htm
Life span is 7 to 14 years, yours is bad.

The link is an interesting read also for anybody trying to establish a lab voltage standard:

It takes a minimum of three cells to maintain the volt with any degree of reliability. With one cell, there is no way to know if a change has occurred. With two cells, a change in either one will be detected, but there is no way to determine which one. With three cells, the errant cell can be identified. In addition, one cell can be sent off for certification, then compared on its return to be sure no shift or damage has occurred. The following rules are condensed from Harris' Electrical Measurements (1952):

    Cells in general laboratory use should be checked against each other frequently. At least one cell should be reserved for such checks, and not be subjected to the hazards of routine operation. Such cells should be sent to a sta..

Regards, Dieter

[Harfner]

This is most likely an unsaturated cell, which is (toxic) waste by now.

[fant]

Just my few cents.

This is the cell from my lab.
Dated April 1964.

Best regards

[Gyro]

That one is a Muirhead saturated standard cell. Unlike the unsaturated ones, it will maintain its voltage until its capacity is exhausted, rather than over time.

The voltage temperature coefficient of Saturated cells is higher though, so they need to be measured with reference to a (stable) ambient temperature. Again, you must not draw any significant current from the cell when measuring.

Datasheet attached (courtesy of a fellow forum member)...


P.S. From your label, it looks as if you know about them!