TAD 4002

[Coytee]

Some interesting tidbits on BE for a Saturday morning.  There will be a test later in the afternoon... 

 

Uniquely strong and light, beryllium is used to make cell phones, missiles and aircrafts. But workers who handle the metal need to watch out, as airborne beryllium has been known to be highly toxic.

Named after beryllos, the Greek name for the mineral beryl, the element was originally known as glucinium — from Greek glykys, meaning "sweet" — to reflect its characteristic taste. But the chemists who discovered this unique property of beryllium also found that it is in fact highly toxic and should therefore never be tasted, according to Jefferson Lab. In fact, the metal, its alloys and salts should only be handled in accordance with specific work codes. Beryllium is also classified as a carcinogen by the International Agency for Research on Cancer and it can cause lung cancer in people who get exposed to beryllium on a daily basis because of their occupations that require them to mine or process the metal, said Dr. Lew Pepper, a medical researcher at Queens College Center for the Biology of Natural Systems in New York.

Despite its toxicity, the element is highly useful because of its unique qualities. For instance, it is one of the lightest metals and has one of the highest melting points among the light metals, according to the Los Alamos National Laboratory. Steel gray in color, beryllium's modulus of elasticity is about one-third greater than steel. Beryllium is nonmagnetic and resistant to concentrated nitric acid. It also has superior thermal conductivity and resists oxidation in air in normal temperatures.

 

Just the facts

• Atomic number (number of protons in the nucleus): 4
• Atomic symbol (on the Periodic Table of the Elements): Be
• Atomic weight (average mass of the atom): 9.012182
• Density: 1.85 grams per cubic centimeter
• Phase at room temperature: Solid
• Melting point: 2,348.6 degrees Fahrenheit (1,287 degrees Celsius)
• Boiling point: 4,479.8 F (2,471 C)
• Number of isotopes (atoms of the same element with a different number of neutrons): 12, including one stable isotope.
• Most common isotopes: ⁹Be (Natural abundance: 100 percent)
• Beryllium discovery and use

Beryllium was discovered in 1798 by the French chemist Louis Nicolas Vauquelin, who found it in the oxide form in beryl and a green-colored variety of beryl, emerald.The metal was isolated in 1828 by two chemists, Friedrich Wölhler from Germany and Antoine Bussy from France, who independently reduced beryllium chloride (BeCl₂) with potassium in a platinum crucible, according to the Jefferson Lab. These days, beryllium is typically obtained from the minerals beryl and bertrandite in a chemical process or through the electrolysis of a mixture of molten beryllium chloride and sodium chloride, the Jefferson Lab reports.

Beryllium is found in about 30 mineral species, including bertrandite, beryl, chrysoberyl, and phenacite, according to the Los Alamos National Laboratory. Beryl and bertrandite are the most important commercial sources of the element and its compounds.

Beryllium is alloyed with copper or nickel to make springs, gyroscopes, electrical contacts, spot-welding electrodes and non-sparking tools, according to the Royal Society of Chemistry. Other beryllium alloys are used in high-speed aircrafts and missiles, as well as spacecraft and communication satellites. Beryllium copper is also used in windshield frame, brake discs, support beams, and other structural components of the space shuttle.

Thanks to its low thermal neutron absorption cross-section, beryllium is used in nuclear reactors as a reflector or moderator. Moreover, the high melting point of beryllium oxide makes it a useful material for nuclear work and ceramic applications, according to the Los Alamos National Laboratory.

[Chris A]

Where beryllium gets toxic is where people are handling the material a lot, or it is being machined such that particles become airborne.  This is a well known hazard (berylliosis) and requires special processing to ensure that no particles are inhaled--as in a glove-box environment for machining, etc..

 

In a benign environment where the metal is not handled or worked--like an acoustic driver diaphragm--there are no more health hazards than say, a radium dial on a watch, exposure to smoke alarms, or a couple or more alcoholic drinks/day.

 

However in a dance club environment where acoustic drivers are routinely driven past their limits and into their "stops", use of beryllium is probably not recommended due to the event of a diaphragm shattering (hence the screen over the diaphragms). 

 

In a home environment, I expect my TAD TD-4002s (bought new) to last forever without increased health risk.  Anyone that's heard them and has the wherewithal for a pair usually own them because there's not much that can compete with them (and I've got acoustic measurement data to show why that is true).  I also don't mess around with the diaphragms--I've not had my TADs apart yet.  I don't expect to ever have to do that.

 

JMTC.

 

Chris

[Schu]

don't lick your diaphragms...

no one has tried the Radian?

[Chris A]

 

Here is a list of other substances and mixtures with similar risks:

 

Substances

• 2-Naphthylamine
• Acetaldehyde^[1] associated with consumption of alcoholic beverages
• 4-Aminobiphenyl
• Aflatoxins
• Aristolochic acids, and plants containing them
• Arsenic and inorganic arsenic compounds^{[note 1]}
• Asbestos
• Azathioprine
• Benzene
• Benzidine, and dyes metabolized to
• Benzo[a]pyrene
• Beryllium and beryllium compounds^{[note 2]}
• Chlornapazine (N,N-Bis(2-chloroethyl)-2-naphthylamine)
• Bis(chloromethyl)ether
• Chloromethyl methyl ether
• 1,3-Butadiene
• 1,4-Butanediol dimethanesulfonate (Busulphan, Myleran)
• Cadmium and cadmium compounds^{[note 2]}
• Chlorambucil
• Methyl-CCNU (1-(2-Chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea; Semustine)
• Chromium(VI) compounds^{[note 2]}
• Ciclosporin
• Clonorchis sinensis (infection with)
• Cyclophosphamide
• 1,2-Dichloropropane
• Diethylstilboestrol
• Epstein-Barr virus
• Estrogen therapy, postmenopausal
• Estrogen-progestogen oral contraceptives (combined)
• Ethanol in alcoholic beverages^{[1][note 3]}
• Erionite
• Ethylene oxide
• Etoposide alone, and in combination with cisplatin and bleomycin
• Fluoro-edenite fibrous amphibole
• Formaldehyde
• Gallium arsenide
• Helicobacter pylori (infection with)
• Hepatitis B virus (chronic infection with)
• Hepatitis C virus (chronic infection with)
• Human herpesvirus 8 (Kaposi sarcoma-associated herpesvirus)
• Human immunodeficiency virus type 1 (infection with)
• Human papillomavirus types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 66
• Human T-cell lymphotropic virus type 1 (HTLV-I)
• Lindane
• Melphalan
• Methoxsalen (8-Methoxypsoralen) plus ultraviolet A radiation
• 4,4'-Methylenebis(2-chloroaniline) (MOCA)
• MOPP and other combined chemotherapy including alkylating agents
• Mustard gas (Sulfur mustard)
• 2-Naphthylamine
• Neutron radiation
• Nickel compounds^{[note 2]}
• 4-(N-Nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK)
• N-Nitrosonornicotine (NNN)
• Opisthorchis viverrini (infection with)
• Outdoor air pollution
• Particulate matter in outdoor air pollution
• 2,3,4,7,8-Pentachlorodibenzofuran
• 3,4,5,3’,4’-Pentachlorobiphenyl(PCB-126)
• Phosphorus-32, as phosphate
• Plutonium
• Radioiodines, short-lived isotopes, including iodine-131, from atomic reactor accidents and nuclear weapons detonation (exposure during childhood)
• Radionuclides, α-particle-emitting, internally deposited^{[note 4]}
• Radionuclides, β-particle-emitting, internally deposited^{[note 4]}
• Radium-224 and its decay products
• Radium-226 and its decay products
• Radium-228 and its decay products
• Radon-222 and its decay products
• Schistosoma haematobium (infection with)
• Silica dust, crystalline (inhaled in the form of quartz or cristobalite from occupational sources)
• Talc containing asbestiform fibres
• Tamoxifen^{[note 5]}
• 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)
• Thiotepa (1,1',1"-Phosphinothioylidynetrisaziridine)
• Thorium-232 and its decay products, administered intravenously as a colloidal dispersion of thorium-232 dioxide
• Treosulfan
• Trichloroethylene
• o-Toluidine
• Vinyl chloride

Radiations

• Ionizing radiation (all types)
• Ultraviolet radiation including solar radiation
• X-Radiation and gamma radiation

Mixtures

• Aflatoxins (naturally occurring mixtures of)
• Alcoholic beverages
• Areca nut
• Betel quid with tobacco
• Betel quid without tobacco
• Coal-tar pitches
• Coal-tars
• Coal, indoor emissions from household combustion of
• Engine exhaust, diesel^[2]
• Estrogen-progestogen menopausal therapy, (combined)
• Estrogen-progestogen oral contraceptives (combined)^{[note 6]}
• Fission products, including Strontium-90
• Leather dust
• Mineral oils, untreated and mildly treated
• Paints containing benzene
• Phenacetin, analgesic mixtures containing
• Plants containing aristolochic acid
• Polychlorinated biphenyls, dioxin-like
• Processed meats, consumption of^[3]
• Salted fish (Chinese-style)
• Shale-oils
• Soot (as found in occupational exposure of chimney sweeps)
• Wood dust

Exposure circumstances

• Acheson process, occupational exposure associated with
• Acid mists, strong inorganic
• Aluminium production
• Auramine production
• Boot and shoe manufacture and repair (see leather Dust and benzene)
• Chimney sweeping (see Soot)
• Coal gasification
• Coal tar distillation
• Coke (fuel) production
• Furniture and cabinet making (see wood dust)
• Haematite mining (underground) with exposure to radon
• Iron and steel founding (occupational exposure to)
• Isopropanol manufacture (strong-acid process)
• Glass, making of
• Magenta dyes, manufacture of
• Painting (see benzene)
• Paving and roofing with coal tar pitch
• Rubber manufacturing industry
• Sandblasting (see silica dust)
• Smokeless tobacco
• Tobacco smoke, second hand
• Tobacco smoking
• Ultraviolet-emitting tanning devices

 

[babadono]

Well the good news is I think mine are Beryllium. So I was worried 'bout nuttin' But i learned why the solder joints looked like crap. Soldering to these plastic binding posts without melting the plastic part is tough. I gave up installed new posts and used crimp terminals on posts. Used nice gold plated quick disconnects for the connection to the diaphragm(thanks Madisound). Also learned with the crimp terminals it gets pretty tight inside the back housing, Only mangled 1 wire so far. One driver down second one coming up.