[AMPS] Operating Hazards - Ceramic tubes et al.
John Fielding
johnf@futurenet.co.za
Sat, 10 Oct 1998 21:14:40 +0200
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Hi all - seems the BeO and other hazards has been quite well aired. I
today received 2 Eimac tubes with a sheet of Operating Hazards which I am
including for interest. I am quoting the Hazard sheet exactly as it is
printed (apologies for the length - but it makes very interesting reading).
"Operating Hazards.
PROPER USE AND SAFE OPERATING PRACTICES WITH RESPECT TO POWER TUBES ARE THE
RESPONSIBILITY OF EQUIPMENT MANUFACTURERS WHO INCORPORATE THE THE TUBE
INTO AND USERS OF SUCH TUBES AND EQUIPMENT. THE SUPPLIER OF THIS POWER
TUBE PROVIDES INFORMATION ON ITS PRODUCTS AND ASSOCIATED HAZARDS, BUT IT
ASSUMES NO RESPONSIBILITY FOR AFTER-SALES OPERATING AND SAFETY PRACTICES.
LIMITED LIFE AND RANDOM FAILURES ARE INHERENT CHARACTERISTICS OF ELECTRON
TUBES. TAKE APPROPRIATE ACTION THROUGH REDUNDANCY OR OTHER SAFEGUARDS TO
PROTECT PERSONNEL AND PROPERTY FROM TUBE FAILURE.
ALL PERSONS WHO WORK WITH OR ARE EXPOSED TO POWER TUBES OR EQUIPMENT WHICH
UTILIZES SUCH TUBES MUST TAKE PRECAUTIONS TO PROTECT THEMSELVES AGAINST
POSSIBLE SERIOUS BODILY INJURY. DO NOT BE CARELESS AROUND SUCH PRODUCTS.
OPERATING INSTRUCTIONS.
This Operating Hazard Sheet, any packing and unpacking instructions, and
relevant test data which may be included with this Power Tube can help you
to operate this tube safely and efficiently. READ THEM. The Technical
Data Sheet for this power tube provides operating specifications for
individual products and other application information. Uninformed or
careless operation of this tube can result in poor performance, damage to
the tube or property, serious bodily injury, and possibly death.
Questions regarding tube operation or safety matters should be addressed to
the Applications Engineering Department.
WARNING - SERIOUS HAZARDS EXIST IN THE OPERATION OF POWER TUBES.
The operation of power tubes involves one or more of the following hazards,
any one of which, in the absence of safe operating practices and
precautions, could result in serious harm to personnel:
a. HIGH VOLTAGE - Normal operating voltages can be deadly. See below for
additional information.
b. RF RADIATION - Exposure to RF radiation may cause serious bodily injury
possibly resulting in blindness or death. CARDIAC PACEMAKERS MAY BE
AFFECTED. See below for additional information.
c. X-RAY RADIATION - High Voltage tubes can produce dangerous, possibly
fatal X-rays. See below for additional information.
d. BERYLLIUM-OXIDE POISONING - Dust or fumes from BeO ceramics used in
thermal links with some conduction cooled power tubes are highly toxic and
can cause serious injury or death. See below for additional information.
e. GLASS EXPLOSION - Many electron tubes have glass envelopes. Breaking
the glass can cause an implosion, which will result in in an explosive
scattering of glass particles. Handle glass tubes carefully. See below
for additional information.
f. HOT WATER - Water used to cool tubes reaches scalding temperatures.
Touching or rupturing of the cooling system can cause serious burns. See
below for additional information.
g. HOT SURFACES - Surfaces of air-cooled radiators and other parts of
tubes can reach temperatures of several hundred degrees centigrade and
cause serious burns if touched. See below for additional information.
Additional specific information about power tube hazards.
HIGH VOLTAGE.
Many power tubes operate at voltages high enough to kill through electrical
shock. Design equipment utilizing these tubes to prevent personnel contact
with high voltages. Securely attach prominent hazard warnings. Personnel
should always break the primary circuits of the power supply and discharge
highvoltage capacitors when direct access to the tube is required.
RADIO FREQUENCY RADIATION.
EXPOSURE OF PERSONNEL TO RF RADIATION SHOULD BE MINIMISED. PERSONNEL
SHOULD NOT BE PERMITTED IN THE VICINITY OF OPEN ENERGISED RF GENERATING
CIRCUITS, OR RF TRANSMISSION SYSTEMS (WAVEGUIDES, CABLES, CONNECTORS,
ETC.), OR ENERGISED ANTENNAS. It is generally accepted that exposure to
"high levels" of rf radiation can result in severe bodily injury including
blindness. CARDIAC PACEMAKERS MAY BE AFFECTED.
The effect of prolonged exposure to "low level" rf radiation continues to
be a subject of investigation and controversy. While there continues to be
support for lower limits, it is generally agreed among official
standard-setting groups in the U.S. that prolonged exposure to personnel to
rf radiation at frequencies of 10 MHz to 100 GHz should be limited to
average power densities of ten milli-watts per square centimetre or lower,
using any possible one tenth of an hour as the averaging period. It is
generally agreed that exposure should be reduced in working areas where
personnel heat load is above normal. The 10mW/cm2 average level has been
adopted by several U.S. Government agencies including the Occupational
Safety and Health Administration (OSHA) as the standard or protection guide
for employee work places.
RF energy must be contained properly by shielding and transmission lines.
ALL INPUT AND OUTPUT RF CONNECTIONS, SUCH AS CABLES, FLANGES AND GASKETS
MUST BE LEAKPROOF. NEVER A POWER TUBE WITHOUT A PROPERLY MATCHED RF ENERGY
ABSORBING LOAD ATTACHED. NEVER LOOK INTO OR EXPOSE ANY PART OF THE BODY TO
AN ANTENNA OR OPEN RF GENERATING TUBE OR CIRCUIT OR RF TRANSMISSION SYSTEM
WHILE IT IS ENERGIZED. MONITOR THE TUBE AND RF SYSTEM FOR RF RADIATION
LEAKAGE AT REGULAR INTERVALS AND AFTER SERVICING.
X-RAY RADIATION.
As operating voltages increase beyond 15kV, power tubes are capable of
producing progressively more dangerous X-ray radiation. Dangerous X-ray
radiation is more likely from high-power transmitting tubes, many pulse
modulator tubes, high-vacuum rectifier tubes, and all older high voltage
tubes that may have undergone changes in emission characteristics with
aging and gradual deterioration. Provide adequate X-ray shielding on all
sides of these tubes, particularly around the anode as well as the
modulator and pulse transformer where they are used. Check X-rays levels.
NEVER OPERATE HIGH VOLTAGE TUBES WITHOUT ADEQUATE X-RAY SHIELDING IN PLACE.
MONITOR THE TUBE AFTER SERVICING AND AT REGULAR INTERVALS FOR POSSIBLE
CHANGES IN X-RAY LEVELS DUE TO AGING.
DANGER: BERYLLIUM OXIDE CERAMICS (BeO) - AVOID BREATHING DUST OR FUMES.
BeO ceramic material is used as a thermal link to carry heat from the tube
to a heat sink in a number of conduction cooled tubes. The BeO thermal
link may be brazed to the anode section of the power tube, or may be a
separate accessory. Do not perform any operation on any BeO ceramic which
might produce dust or fumes, such as grinding, grit blasting, and acid
cleaning. BERYLLIUM OXIDE DUST OR FUMES ARE HIGHLY TOXIC AND BREATHING
THEM MAY RESULT IN SERIOUS PERSONAL INJURY OR DEATH. Because BeO warning
labels may become obliterated or removed, you are urged to contact your
tube supplier before performing any work which might affect any external
thermal link on any conduction-cooled power tube.
When BeO ceramics are to be salvaged or disposed of, special precautions
must be taken to protect personnel. All such personnel must be made aware
of the deadly hazards involved and the necessity of great care and
attention to safety precautions. Any tube with a BeO thermal link, or any
separate BeO thermal link will be disposed of without charge, provided it
is returned freight pre-paid to the supplier from which it was purchased
with a written request for disposal. The supplier will then return it to
the manufacturer for proper disposal.
GLASS EXPLOSION.
Every power tube is pumped to a very high vacuum, which, in some cases, is
contained by a glass envelope. When handling glass tubes, remember that
glass is a relatively fragile material, and accidental breakage can result
at any time. Breakages can cause an implosion, which will result in an
explosive scattering of flying glass particles and fragments. Serious
personal injury can result. When handling such tubes, safety glasses (or
even better, a face shield), heavy clothing and leather gloves should be
worn for protection.
HOT WATER.
EXTREME HEAT occurs in the anode portion of power tubes during operation.
Water channels used for cooling also reach high temperatures (as high as
boiling 100C or 212F or above) and the hot water is under pressure
(sometimes as high as 100psi). A rupture of the water channel or other
contact with hot portions of this tube could scald or burn. Take
precautions to prevent and avoid such rupture or cantact.
HOT SURFACES.
The anode portion of power tubes is often air-cooled or conduction-cooled.
The air cooled external surface normally operates at a high temperature (up
to 200 to 300C). Other portions of the tube may also reach temperatures,
especially the cathode insulator and the cathode/heater surfaces. All hot
surfaces may remain hot for an extended time after the tube is shut off.
To prevent serious burns, take care to prevent and avoid any bodily contact
with these surfaces both during and for a reasonable cool-down period after
tube operation.
Varian/Eimac Division 1/80 "
So there you are. Makes scary reading! Maybe we should all ditch these
"nasty power tubes" and build QRP transmitters ?
BTW - the boxes the tubes came in stated that the tube (2C39BA) has a
service life of 1000 hours!
It also carries a NSN (Nato Stock Number) and date on each tube is 8742 so
they are now 11 years old.
John ZS5JF
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<html><head></head><BODY bgcolor=3D"#FFFFFF"><p><font size=3D2 =
color=3D"#000000" face=3D"Arial">Hi all - seems the BeO and other =
hazards has been quite well aired. I today received 2 Eimac tubes =
with a sheet of Operating Hazards which I am including for interest. =
I am quoting the Hazard sheet exactly as it is printed (apologies =
for the length - but it makes very interesting =
reading).<br><br>"Operating Hazards.<br><br>PROPER USE AND SAFE =
OPERATING PRACTICES WITH RESPECT TO POWER TUBES ARE THE RESPONSIBILITY =
OF EQUIPMENT MANUFACTURERS WHO INCORPORATE THE THE TUBE INTO AND =
USERS OF SUCH TUBES AND EQUIPMENT. THE SUPPLIER OF THIS POWER TUBE =
PROVIDES INFORMATION ON ITS PRODUCTS AND ASSOCIATED HAZARDS, BUT IT =
ASSUMES NO RESPONSIBILITY FOR AFTER-SALES OPERATING AND SAFETY =
PRACTICES. LIMITED LIFE AND RANDOM FAILURES ARE INHERENT =
CHARACTERISTICS OF ELECTRON TUBES. TAKE APPROPRIATE ACTION THROUGH =
REDUNDANCY OR OTHER SAFEGUARDS TO PROTECT PERSONNEL AND PROPERTY FROM =
TUBE FAILURE.<br><br>ALL PERSONS WHO WORK WITH OR ARE EXPOSED TO POWER =
TUBES OR EQUIPMENT WHICH UTILIZES SUCH TUBES MUST TAKE PRECAUTIONS TO =
PROTECT THEMSELVES AGAINST POSSIBLE SERIOUS BODILY INJURY. DO NOT =
BE CARELESS AROUND SUCH PRODUCTS.<br><br>OPERATING =
INSTRUCTIONS.<br><br>This Operating Hazard Sheet, any packing and =
unpacking instructions, and relevant test data which may be included =
with this Power Tube can help you to operate this tube safely and =
efficiently. READ THEM. The Technical Data Sheet for this =
power tube provides operating specifications for individual products and =
other application information. Uninformed or careless operation of =
this tube can result in poor performance, damage to the tube or =
property, serious bodily injury, and possibly death.<br><br>Questions =
regarding tube operation or safety matters should be addressed to the =
Applications Engineering Department.<br><br>WARNING - SERIOUS HAZARDS =
EXIST IN THE OPERATION OF POWER TUBES.<br><br>The operation of power =
tubes involves one or more of the following hazards, any one of which, =
in the absence of safe operating practices and precautions, could result =
in serious harm to personnel:<br><br>a. HIGH VOLTAGE - Normal =
operating voltages can be deadly. See below for additional =
information.<br><br>b. RF RADIATION - Exposure to RF radiation may =
cause serious bodily injury possibly resulting in blindness or death. =
CARDIAC PACEMAKERS MAY BE AFFECTED. See below for additional =
information.<br><br>c. X-RAY RADIATION - High Voltage tubes can =
produce dangerous, possibly fatal X-rays. See below for additional =
information.<br><br>d. BERYLLIUM-OXIDE POISONING - Dust or fumes =
from BeO ceramics used in thermal links with some conduction cooled =
power tubes are highly toxic and can cause serious injury or death. =
See below for additional information.<br><br>e. GLASS =
EXPLOSION - Many electron tubes have glass envelopes. Breaking the =
glass can cause an implosion, which will result in in an explosive =
scattering of glass particles. Handle glass tubes carefully. =
See below for additional information.<br><br>f. HOT WATER - =
Water used to cool tubes reaches scalding temperatures. =
Touching or rupturing of the cooling system can cause serious =
burns. See below for additional information.<br><br>g. HOT =
SURFACES - Surfaces of air-cooled radiators and other parts of tubes can =
reach temperatures of several hundred degrees centigrade and cause =
serious burns if touched. See below for additional =
information.<br><br>Additional specific information about power tube =
hazards.<br><br>HIGH VOLTAGE.<br><br>Many power tubes operate at =
voltages high enough to kill through electrical shock. Design =
equipment utilizing these tubes to prevent personnel contact with high =
voltages. Securely attach prominent hazard warnings. =
Personnel should always break the primary circuits of the power =
supply and discharge highvoltage capacitors when direct access to the =
tube is required.<br><br>RADIO FREQUENCY RADIATION.<br><br>EXPOSURE OF =
PERSONNEL TO RF RADIATION SHOULD BE MINIMISED. PERSONNEL SHOULD =
NOT BE PERMITTED IN THE VICINITY OF OPEN ENERGISED RF GENERATING =
CIRCUITS, OR RF TRANSMISSION SYSTEMS (WAVEGUIDES, CABLES, CONNECTORS, =
ETC.), OR ENERGISED ANTENNAS. It is generally accepted that exposure to =
"high levels" of rf radiation can result in severe bodily =
injury including blindness. CARDIAC PACEMAKERS MAY BE =
AFFECTED.<br><br>The effect of prolonged exposure to "low =
level" rf radiation continues to be a subject of investigation and =
controversy. While there continues to be support for lower limits, =
it is generally agreed among official standard-setting groups in the =
U.S. that prolonged exposure to personnel to rf radiation at frequencies =
of 10 MHz to 100 GHz should be limited to average power densities of ten =
milli-watts per square centimetre or lower, using any possible one tenth =
of an hour as the averaging period. It is generally agreed that =
exposure should be reduced in working areas where personnel heat load is =
above normal. The 10mW/cm2 average level has been adopted by =
several U.S. Government agencies including the Occupational Safety and =
Health Administration (OSHA) as the standard or protection guide for =
employee work places.<br><br>RF energy must be contained properly by =
shielding and transmission lines. ALL INPUT AND OUTPUT RF =
CONNECTIONS, SUCH AS CABLES, FLANGES AND GASKETS MUST BE LEAKPROOF. =
NEVER A POWER TUBE WITHOUT A PROPERLY MATCHED RF ENERGY ABSORBING =
LOAD ATTACHED. NEVER LOOK INTO OR EXPOSE ANY PART OF THE BODY TO =
AN ANTENNA OR OPEN RF GENERATING TUBE OR CIRCUIT OR RF TRANSMISSION =
SYSTEM WHILE IT IS ENERGIZED. MONITOR THE TUBE AND RF SYSTEM FOR =
RF RADIATION LEAKAGE AT REGULAR INTERVALS AND AFTER =
SERVICING.<br><br>X-RAY RADIATION.<br><br>As operating voltages increase =
beyond 15kV, power tubes are capable of producing progressively =
more dangerous X-ray radiation. Dangerous X-ray radiation is more =
likely from high-power transmitting tubes, many pulse modulator tubes, =
high-vacuum rectifier tubes, and all older high voltage tubes that may =
have undergone changes in emission characteristics with aging and =
gradual deterioration. Provide adequate X-ray shielding on all =
sides of these tubes, particularly around the anode as well as the =
modulator and pulse transformer where they are used. Check X-rays =
levels. NEVER OPERATE HIGH VOLTAGE TUBES WITHOUT ADEQUATE X-RAY =
SHIELDING IN PLACE. MONITOR THE TUBE AFTER SERVICING AND AT =
REGULAR INTERVALS FOR POSSIBLE CHANGES IN X-RAY LEVELS DUE TO =
AGING.<br><br>DANGER: BERYLLIUM OXIDE CERAMICS (BeO) - AVOID =
BREATHING DUST OR FUMES.<br><br>BeO ceramic material is used as a =
thermal link to carry heat from the tube to a heat sink in a number of =
conduction cooled tubes. The BeO thermal link may be brazed to the =
anode section of the power tube, or may be a separate accessory. =
Do not perform any operation on any BeO ceramic which might =
produce dust or fumes, such as grinding, grit blasting, and acid =
cleaning. BERYLLIUM OXIDE DUST OR FUMES ARE HIGHLY TOXIC AND =
BREATHING THEM MAY RESULT IN SERIOUS PERSONAL INJURY OR DEATH. =
Because BeO warning labels may become obliterated or removed, you =
are urged to contact your tube supplier before performing any work which =
might affect any external thermal link on any conduction-cooled power =
tube.<br><br>When BeO ceramics are to be salvaged or disposed of, =
special precautions must be taken to protect personnel. All such =
personnel must be made aware of the deadly hazards involved and the =
necessity of great care and attention to safety precautions. Any =
tube with a BeO thermal link, or any separate BeO thermal link will be =
disposed of without charge, provided it is returned freight pre-paid to =
the supplier from which it was purchased with a written request for =
disposal. The supplier will then return it to the =
manufacturer for proper disposal.<br><br>GLASS EXPLOSION.<br><br>Every =
power tube is pumped to a very high vacuum, which, in some cases, is =
contained by a glass envelope. When handling glass tubes, remember =
that glass is a relatively fragile material, and accidental breakage can =
result at any time. Breakages can cause an implosion, which will =
result in an explosive scattering of flying glass particles and =
fragments. Serious personal injury can result. When handling =
such tubes, safety glasses (or even better, a face shield), heavy =
clothing and leather gloves should be worn for protection.<br><br>HOT =
WATER.<br><br>EXTREME HEAT occurs in the anode portion of power tubes =
during operation. Water channels used for cooling also reach high =
temperatures (as high as boiling 100C or 212F or above) and the hot =
water is under pressure (sometimes as high as 100psi). A rupture =
of the water channel or other contact with hot portions of this tube =
could scald or burn. Take precautions to prevent and avoid such =
rupture or cantact.<br><br>HOT SURFACES.<br><br>The anode portion of =
power tubes is often air-cooled or conduction-cooled. The air =
cooled external surface normally operates at a high temperature (up to =
200 to 300C). Other portions of the tube may also reach =
temperatures, especially the cathode insulator and the cathode/heater =
surfaces. All hot surfaces may remain hot for an extended time =
after the tube is shut off. To prevent serious burns, take care to =
prevent and avoid any bodily contact with these surfaces both during and =
for a reasonable cool-down period after tube =
operation.<br><br><br><br>Varian/Eimac Division 1/80 =
"<br><br><br><br><br>So there you are. Makes =
scary reading! Maybe we should all ditch these "nasty =
power tubes" and build QRP transmitters ?<br><br>BTW - the boxes =
the tubes came in stated that the tube (2C39BA) has a service life of =
1000 hours!<br>It also carries a NSN (Nato Stock Number) and date on =
each tube is 8742 so they are now 11 years =
old.<br><br><br>John	ZS5JF<br><br><br><br> =
	 </p>
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