Storing valves

[WreckTangle]

My salvaged valves are individually wrapped in tissue paper in a shoe-box in the loft. My small collection of NOS valves are in their original boxes in a desk drawer. Never had a problem with either.

[Techman]

Freezing temperatures has nothing to do with it. Many hundreds of other valves stored in the same conditions are still perfectly sound. A ‘well known’ forum member found an old TV chassis in a hedge bottom on a farmers private field. The chassis had been there since the 60s I think and had corroded badly but what valves were left were still ok and I seem to remember the tube was still sound. I think I’ve got the story right and there’s a thread about it on here somewhere. Anyway, there’s many other cases of valves being found outside that have survived.

Valves cracking from the pins and going to air have got to be caused by something else that we don’t know. Maybe it’s a design problem or a batch fault?

[ionburn]

I tend to store valves carefully and luckily have had no issues except for the printing on some which tends to become very fugitive if the valve has been subject (I suspect) to a dampish atmosphere.

These days they are stored in a drier atmosphere boxed both individually and collectively in larger boxes

[Alan Stepney]

I have a chest of drawers in the shack/workshop, with each drawer holding valves that I commonly use arranged by base type per drawer. (One for IO, one for B9A etc.)

The rest of my collection is packed in numbered boxes in the loft, with all of them listed on a spreadsheet.
Apart, that is, from the unusual / rare ones which are in glass fronted cabinets in the lounge.

[turretslug]

I'd be really quite surprised if a British garage in winter would result in a significant degree of envelope cracking- though I'm open to enlightenment!

As just one anecdotal example, there must have been a few decades of experience of valved avionics kit that would sit out on a remote apron in northern Canada or Russia in winter for days at a time unpowered that would "just work" on starting. Even if this stuff used more expensive, professional-coded valves, I'm sceptical that envelope/lead-out technology would have been vastly different/more sophisticated compared to consumer valves. Also, some modern "boutique" valve suppliers talk about "cryogenically treated" valves, supposedly lowered to extreme temperatures to make them very wonderful- the cynic in me says that if there was more than a slight failure rate, they wouldn't bother.

It's conceivable that moisture on lead-outs might cause corrosion that could crack an envelope at this point- when metals decide they want to become an oxide or salt, the expansion in volume can exert extraordinary pressure and I suppose this could provoke point-stress leading to crack propogation- think of those ageing bridges with rusting steel causing spalled concrete.

As a quick, easy first-line protection before more diligent wrapping/boxing of the more worthwhile bottles, I'll slip acquired loose valves into individual re-sealable poly-bags before putting them into a tray en masse- not indestructable protection, but at least eases the glass-glass clash when rattling around, and helps save pips/pins from point loading and ephemeral print from too much damage. A size to accomodate up to middling power B9a types can typically be acquired at a few pounds for 1,000 if you look around- a fraction of a penny per bottle, so even 6AL5s deserve one! Put another way, a bit of peace of mind for many valves for about what one second-hand EL84 might realise.

[RF Burn]

Please forgive me, I was only adding my personal observations to the discussion.

My simple logic says that if valves from the same manufacturer and of the same type and similar age are stored in exactly the same conditions in manufacturer's packaging and not subject to any significant physical forces, then any problems are due to the only remaining differences which would be temperature and possibly humidity. (OK, so there would also be differences in noise and light levels, but I will not seriously consider those).

If there is a manufacturing defect then why would it show up in multiple examples of the same type of valve at roughly the same time after having being stored elsewhere for 30 or more years?

Hence my assumption, or perhaps I should have described it as a theory? Also there are others writing in other forums who have had similar experiences and come to similar conclusions, cold temperature cycling of the pin seals being the favourite theory.

Are not military/commercial (or critical) parts storage facilities kept under temperature and humidity control?

Did any of the traditional valve manufacturers ever use or promote 'cryo-treatment'? I thought that was just snake-oil.

However I am just an 'umble electronics engineer, I bow to those with expertise in metallurgy and glass technology.

[Alan Stepney]

The actual test procedure for new valves (at Mullard and probably other manufacturers) was far more severe than any storage conditions, or the modern "treatment" to (allegedly) enhance them.

Valves are EXTREMELY rugged, and will withstand all sorts of abuse before failing.

The chance of finding an unused one that has failed is small.

Just use them and dont worry about it.

[Techman]

I think my statement of “Freezing temperatures has nothing to do with it” came over not quite as I intended and probably sounded a bit ‘sharp’.

Now here’s a thing – the valves that I had go to air while in the loft were packed in their original valve boxes, not only that, but they were then all packed within a second box with a good lid. Meanwhile, hundreds of ‘pulls’ in open top boxes below the freezing roofing felt and roof tiles are all fine. I know they’re all fine as I have a rummage through them from time to time when looking for a particular valve and the only ones that go to air are the ones I accidentally knock the pips off while rummaging! Also, many other valves in proper boxes seem to have survived up there.

I think there’s something else going on here. I notice that all the valves have cracked from a heater pin except one that has cracked from a heater pin and two other pins as well. It’s notable that these particular valves are 6.3 volt heater versions of an old American TV line output valve. The heater current is getting on for 3 amps. The original TV version of this valve would have had something like a 40 volt heater operating at a much lower heater current. I have a theory that the design of these valves can’t cope with that sort of heater current passing through the pins where they bond to the glass – I could be completely wrong, though.

I’ve just remembered that there was one other 6KD6 valve that a friend gave me many years ago and that due to them being an obscure American 12 pin base, he’d clipped off the unnecessary pins level with the glass with side cutters and bent the remaining pins with pliers to force it to fit into a British EL509 base – this valve was with the others in it’s box and hadn’t gone to air and still works, all be it with low emission.

I am a bit conscious of the fact that some of this discussion may be considered to be not quite on the topic of actual ‘valve storage’.

Here’s a couple of pictures of what’s happened to my valves. The first one on the left is not a GE type and was the one that cracked the other day down here in the warm room in the middle of summer -

[AC/HL]

Some SQ valves had plastic pin protectors, so keeping them straight must have been deemed at least desirable. CRTs also often had them.