Mercury relays? (UPDATED: Pics post #20)

Originally Posted by scrappinred

i have a lot of boards with relays, but i have no idea how to know if they are mercury or not. I look forward to anyone posting pics and identification details...


I have a lot of relays that look like this:



...and i think they are not mercury... ?

gotta love those with the silver buttons. I saved a bunch of those and ones in blue and black boxes. At least i believe those are silver buttons you can clip off.

Originally Posted by ScrappinRed

I have a lot of boards with relays, but I have no idea how to know if they are mercury or not. I look forward to anyone posting pics and identification details...

I have a lot of relays that look like this:



...and I think they are not mercury... ?

No mercury in this type of relay, most have silver alloy bonded onto the contact face while those used in sever elements for example Thermo King truck reefers or from relays used in a PLC ( programmable logic controller ) used in a harsh environment would have gold alloy bonded onto the face of the contacts.

PLC Logic Board, these come in may different arrangements and styles,

Originally Posted by eesakiwi

I have found Mercury relays in Heating equipment thermostats, this was the unit that was screwed to the outside wall of a community Hall. (So it was old and semi industrial setting).

In the electrical cabinets of some industrial equipment. I have no idea what it controlled, maybe a furnace or something.

In the on/off switch of a portable Hospital vacuum pump.

You may also find them in the AC/DC ( \m/,) rectifier in vintage valve radios and amplifiers.

Google image these parts and switches to see what they look like.

The main reason why they use Mercury in switches is because there's no arcing at the contact face, so that means there's no sparks to inginite any flammable fumes in the air (such as the hospital).

The hall thermostat was a bimetal 'tipping' action, once the metal strip moved the glass vial so far, the Mercury ran from one end of the tube to the other and made a electrical contact across the two contacts, turning whatever it was, On.
(Same sort of 'tipping action' in the hospital vacuum pump too)

The rectifier.... These are real neat, a double W shaped glass globe with Mercury in the base.
Wiki it see one. And find out how they work, amazing. The ones in valve radios are small eggcup size.
But the same system, as large as a fridge, turns the AC electricity from huge hydro power stations into DC power, for long distance and under sea cable transmission.

The main thing with these Mercury relays/switches, is that they are inside a Glass tube with Copper wires going into it. You can see the Mercury inside it.
Also, while it does feel good to shake the vial and feel the Mercury slosh around inside it....
Don't.!
Mercurys pretty heavy and can break the end out of the glass tube..

The relay you pictured above is the sort you will find quite often while scrapping metal.
That ones got Silver/Copper contacts in it.
If there's Three contacts in it, often the centre one is solid Silver. (Actually its got Cadmium in it as well, its poisonous to inhale, so don't melt it down)
Most of the time the Silver is a button melted to the Copper backing, so its worth a little amount of money.
Cheaper contacts have only a thin electroplated face of Silver.

Though some contacts are Gold plated Silver or even solid Gold. You find these in slim and small relays, mostly the sorts that are 'onboard' circuit boards and such. Sometimes open air contacts in CD drive units, double tapedeck units, floppy drive units.
European dishwashers and driers like to have Gold plated contacts in their switches too.

I have found that others will have good Silver contacts in their switches, and dryer motors (NZ anyway) have huge solid Silver contacts on/inside the motors.

Last thing (thank God for auto update..) You may find 'reed switches', they are a thin glass tube with a wire out each end and two thin metal strips inside the glass tube. (No Mercury inside it)
Google image it.
Sometimes they are inside a plastic rectanglular block on a circuit board with a small Copper wire coil around it, encased in epoxy.
I get the impression they have a Platinum coating over Gold, over Copper, on Steel wire.
_-----—--------------

Added later.......
Wow! I just had a Google and found this site.
NEWMOA - Mercury Legacy Products - Appliances & Household Products

Even a quick look tells me it would be pretty important for all of us to read the whole site.
Basicly its got a long list of everything we can expect to find Mercury in, and where.

The first three items, I had no idea that they could contain Mercury at all.

Some of the older washing machines used a mercury lid switch the mercury is encapsulated in a hard rubber or plastic shell with a pair of wires coming out one end. I would love to find one to make a decent float switch for my bilge pump on my boat.

Kenmore and Inglis to name a few had them.

don't know about mercury but a few months ago I got more relays than I could ever handle could not even move them myself I found a buyer for all them and dint mind any loses as I would never have been able to tear them all down but I bid $100 and won a lot as in alot lol 5,000,000 of these old 60's era pkm1 relays from Russia with silver contacts almost 11 pallet boxes filled to there brim with these. none really in good shape like they were bad made or ripped out of things, I dint get a story but that they were stored in a warehouse and forgot about.
they were worth $15,000 to me from my buyer which was just fine even if they were worth $10each I dint care cause I had to move them fast with no space to save them or for that matter move them without dumping loads into my truck as I had 24hrs to take them or forfeit but could not find more info on them and their worth but a few ebay items that never sold

^^Are you saying you paid $100 for 11 gaylords full, and sold for $15,000? If so, congratulations!

Originally Posted by TheRecycleGuy

gotta love those with the silver buttons. I saved a bunch of those and ones in blue and black boxes. At least i believe those are silver buttons you can clip off.

I set up an old bench grinder with water on the wheel just like a lapidary grinder inside an old drawer to catch the crap coming off the contacts, just break the reeds off then grind the contact off save the dust. Since the dust coming off is wet it stays in the bottom of the drawer to be collected later.

You will find that most of the contacts are heavily plated and not a solid silver alloy.

Not sure exactly what type of mercury relay Ewasted is concerned about (probably any type). Here is one type that is used on circuit boards.


Mercury Wetted Reed Relay: are used for high contact performance. These reed relays are position sensitive and suitable for applications where high insulation voltage and contact ratings are required. The contacts of these relays are wetted with mercury, which is used to reduce the contact resistance and voltage drop.

Originally Posted by bigburtchino

Not sure exactly what type of mercury relay Ewasted is concerned about (probably any type). Here is one type that is used on circuit boards.


Mercury Wetted Reed Relay: are used for high contact performance. These reed relays are position sensitive and suitable for applications where high insulation voltage and contact ratings are required. The contacts of these relays are wetted with mercury, which is used to reduce the contact resistance and voltage drop.

Ouch!
I would have said 'Reed relay' and broken it open.....
I didn't relise there's Mercury in reed relays at all.

Some of then ones I found have a metal case over them.

And I found these on some portable home telephone main boards.


There's a thin wire Copper coil under the blue tape, and the reed switch is inside the plastic tube former.

Our old thermostat in the hall had a mercury switch. It was clear glass and you could see the mercury inside.

I've never seen a mercury switch on any of the computers, telephone systems or any circuit boards associated with either. I must say that I haven't been looking for them either.

This thread is one of the reasons why I don't depopulate circuit boards. I have no idea what might be inside some of the different components.

The last thing I need is mercury poisoning or to bust open something only to have some green flesh eating goo get on me.

Thanks for asking this, NA. It was driving me nuts!

This informative PDF file from Greenpeace lists all the toxic elements used to manufacture electronics.

http://www.greenpeace.org/internatio...ls-in-elec.pdf

The following is copied from a handout from Ohioepa. Gives a pretty good overview of some of the hazardous waste associated with E-waste handling.

Hazardous components of electronic waste and where they are found
Electronic waste or e-waste often has hazardous or toxic components that can have an impact on the environment once the materials end up in a landfill or if they are improperly managed and disposed. Below is a list of hazardous or toxic components of e-waste and where they may be found:

• Antimony trioxide - a flame retardant, added to cathode ray tube monitor (CRT) glass, found in printed circuit boards and cables
• Arsenic - in older cathode ray tubes and in light emitting diodes
• Barium - in the CRT
• Beryllium - often allied with copper to improve copper's strength, conductivity and elasticity. Old motherboards, contact springs found in printed circuit boards, relays, and in the mirror mechanism of laser printers. In power supply boxes which contain silicon controlled rectifiers and x-ray lenses
• Cadmium - circuit boards and semiconductors Rechargeable NiCd-batteries, fluorescent layer (CRT screens), printer inks and toners, photocopying-machines (printer drums)
• Chlorofluorocarbon (CFC) - Cooling unit, Insulation foam
• Chromium - in steel as corrosion protection, Data tapes, floppy-disks, circuit boards, photocopying-machines (printer drums)
• Cobalt - component in steel for structural strength and magnetivity
• Lead - cathode ray tubes, solder, batteries, printed wiring boards (circuit boards), solder on components
• Lithium - batteries
• Mercury - switches (mercury wetted) and housing, fluorescent lamps providing backlighting in liquid crystal displays (LCDs) for monitors and laptops, batteries, printed circuit boards
• Nickel - batteries, electron gun in CRT , printed circuit boards
• Polybrominated flame retardants (including polychlorinated biphenyls (PCB), polybrominated biphenyls (PBB), Polybrominated diphenyl ethers (PBDE), and tetrabromo bis-biphenol-a (TBBA))- plastic casings, cables, and circuit boards, condensers, transformers
• Polyvinyl chloride (PVC) - Cable insulation
• Selenium - circuit boards as power to supply rectifier, photocopying-machines (printer drums)
• Zinc - interior of CRT screens, printed circuit boards

There are many sites that can provide more information on the toxics in e-waste, including:
http://latitude42.org/cgi-bin/view/Main/IctToxins
www.e-waste.org.za/hazmat.htm
www.smalldog.com/ewaste/index.html