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Old 30th Jan 2023, 11:02 pm   #1
Richardgr
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Default Cold weather and valves.

There is a thread on this site where a couple of the people replying to a request for valves discovered they had some that were damaged due to the recent cold snap in the UK. That was news to me, and now I am worried for the storage I have for my tubes.

ECL82 wanted

What are the storage needs for valves?
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Old 30th Jan 2023, 11:17 pm   #2
terrybull
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Default Re: Cold and valves

I have never considered this at all and don't know the answer but some google research the general consensus is if they have been stored in a very cold location it is good practice to let them warm to room temperature (assuming the room is comfortably warm) before switching them on.
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Old 30th Jan 2023, 11:27 pm   #3
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Default Re: Cold and valves

Temperature variation seems to be the main problem. Valves are often stored under the roof in a loft space or in a garden shed, and these places can get very hot in summer and very cold in winter.
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Old 31st Jan 2023, 12:55 am   #4
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Default Re: Cold and valves

Pinch seal and wire ended valves are much less prone to going to air in low temperatures. The mechanism of the phenomenon with glass miniature types being particularly, but not exclusively prone, is due to the connection pin reducing in size as it enters the glass seal. In some types the the sealing interface is stressed by the shoulder to the point that it eases the wire and breaks the vacuum.

A known problem in early avionics using valves in such style as the EF50. Early equipment would be switched on and warmed up before take off to stop failures at altitude.

Commodity valves as used in TV and radio, normally don't often suffer in normal conditions, but the garden shed as Paul has pointed out may over time experience perhaps 50°C gradient. Eventually the valve will go to air with no immediately visible damage.

Greg.
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Old 31st Jan 2023, 2:46 am   #5
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Default Re: Cold and valves

Some years ago I sold a quite expensive valve on an auction site. Very many days later, I got a pictures of the valve with the gettering deposit having gone white and demanding a refund, which I had to do. There was absolutely no sign of physical damage.

Although the delivery address was in Cardiff, the buyer was actually located in Hong Kong. I guess that the valve went to air in the cargo hold of an aircraft at high altitude, and somewhere well up in to the Arctic region.

There are one or two lessons to be learned there!

B
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Old 31st Jan 2023, 8:11 am   #6
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Default Re: Cold and valves

I've had the odd valve crack and go to air in Tek 500 series scopes over the years, see the latest, an ECC83 & ECC88 out of a 533A. The ECC88 has several big cracks, they seem especially prone as I've had more 88's go to air than any others. These being in the valve bases in a scope in a shed.

Never had an octal go to air or bigger OP valves.

Andy.
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Old 31st Jan 2023, 10:34 am   #7
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Default Re: Cold weather and valves.

Hi.
I've had the problem on occasions and yes two ECL82s recently, sadly they are stored in the shed as I've no other place to store them. Perhaps it's time to part with some valves before the problem gets worse.
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Old 31st Jan 2023, 1:15 pm   #8
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Default Re: Cold weather and valves.

I wonder if there are two issues here:
1) Rapid temperature changes from cold extremes.
2) Possibly also corrosion on pins, through moisture from temperature changes and humidity, and the corrosion stressing the glass where the pin passes through.

My valves are in an unheated room in Sweden so temperature changes are gradual, but they will see temperatures of below freezing fairly frequently.

When the time comes, I will just have to advertise them as 'cryogenically treated' ;-/
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Old 2nd Feb 2023, 2:57 pm   #9
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Default Re: Cold weather and valves.

Sorry to "jump in" but no one has mentioned, most of these valves are possibly over 50 years old. Is there any information regarding the ability of glass and glass to metal to sustain its original quality over such a long time. I suspect valve manufacturers were only concerned with the "now" factor. Not expecting their products to be around 50 - 70 years in the future. Bit like the radio equipment used in WW2, not expected to survive more than a few weeks.
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Old 2nd Feb 2023, 4:27 pm   #10
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Default Re: Cold weather and valves.

Surely they can cope with a bit of a temperate winter, considering the things need red-hot parts in order to work?
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Old 2nd Feb 2023, 5:39 pm   #11
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Default Re: Cold weather and valves.

I had an early CRT implode in my bedroom when I lived with my parents. I always suspected that the event was triggered by a sudden change in temperature.
It was in 1963, during the big freeze. Luckily I was out at work. The temperature in the room was exceedingly cold, ice on the inside of the window.

It seems that the bedroom door had been left ajar, and a heater put on the landing, to try and thaw out our frozen water tank, in the loft above.
By the time I returned home in the evening, there was a circular cut-out on the lino, where the CRT had been, face down. The shards of glass were everywhere!

David.
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Old 2nd Feb 2023, 6:46 pm   #12
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Default Re: Cold weather and valves.

Quote:
Originally Posted by Uncle Bulgaria View Post
Surely they can cope with a bit of a temperate winter, considering the things need red-hot parts in order to work?
Repeated temperature cycling seems to be the killer, particularly if it happens quickly. Valves stored in sheds or lofts will also tend to acquire condensation moisture which may cause freeze-thaw stress.
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Old 2nd Feb 2023, 7:05 pm   #13
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Default Re: Cold weather and valves.

I read one of the special quality acceptance tests a year or two ago, one trial following production was that 100% of all tubes ( it was America manufacturer possibly GE) underwent so many cycles of being cooled then immersed in boiling water and repeated some tens of times.

So called corrosion jacking where corrosion from damp storage enters a button base alongside a pin and leads to stress fractures and failure of the glass to metal seal.

I have wondered if many valves come pre stressed from production from being allowed to cool too rapidly after the base is flame welded to the envelope?
I very much doubt that there was much effort put into a gradual post production annealing process after evacuation.
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Old 2nd Feb 2023, 9:03 pm   #14
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Default Re: Cold weather and valves.

Stresses in glass can possibly be spotted using polarised light and sunglasses.
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Old 2nd Feb 2023, 9:27 pm   #15
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Default Re: Cold and valves

Quote:
Originally Posted by Diabolical Artificer View Post
I've had the odd valve crack and go to air in Tek 500 series scopes over the years, see the latest, an ECC83 & ECC88 out of a 533A. The ECC88 has several big cracks, they seem especially prone as I've had more 88's go to air than any others. These being in the valve bases in a scope in a shed.

Never had an octal go to air or bigger OP valves.

Andy.
Those pins look quite corroded, same as failures I've had in stuff I've bought, that were showing the signs of being stored in damp places.
Also had numerous cold cathode displays fail with corrosion related cracks, both wire ended & pin types.

Not all were related to damp storage, recently found a cracked valve in my HP TDR plug-in, that had been stored in a spare room in the house.

David
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Old 2nd Feb 2023, 11:16 pm   #16
VT FUSE
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Default Re: Cold weather and valves.

The valve in photo number3 of thread number 6 is a classic corrosion jacking failure, I have seen this even in new unopened valves where storage in damp or humid conditions was a factor and one or more pins has green Verdigris deposits adjacent to the pin entry.
If this type of corrosion is brushed off and the valve is examined with magnification a necking or wasting can be observed and often extends within the glass base and the valve has subsequently cracked in use.
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Old 3rd Feb 2023, 4:45 pm   #17
David Simpson
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Default Re: Cold weather and valves.

Quote:
Originally Posted by Bazz4CQJ View Post
Some years ago I sold a quite expensive valve on an auction site.
Bazz, that China/Cardiff guy is probably the same one who tried that same scammo on me several years ago, with a thumping big NOS 1930's Triode(fully tested & graphed on my DC Tester). What I told him to do with it would have made his eye water & his voice squeak. 'Twas about the same time as an Italian chap(known about in BVWS circles) was trying the same ploy.
Sadly, there are internet wheeler/dealers parasites who prey on our VR fraternity.

Regards, David
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Old 4th Feb 2023, 9:31 am   #18
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Default Re: Cold weather and valves.

Yep, the leads are corroded, the scope has probably been stored in less than perfect conditions since the 1970's or maybe even before that. I've found ECC88's/6DJ8's fracture more than any other valve. I suspect there's a different thermal contraction of the valve glass envelope and the valve pins/base when it's in a socket.

Andy.
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Old 4th Feb 2023, 3:19 pm   #19
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Default Re: Cold weather and valves.

This thread has been very interesting, especially as all the valves in the set I rescued (https://vintage-radio.net/forum/showthread.php?t=195542) had been sitting out in all weathers and seasons, yet none had any failure points and worked !!

Perhaps being in their sockets protected them?
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