Tenmars TM-91N User manual

RADIATION METER
TM-91N
HB2TM91N0001
TENMARS ELECTRONICS CO., LTD

EN-2
CONTENTS
1. introduction .............................................3
2. Safety Precaution....................................4
3. Specification............................................6
4. Identifying parts.......................................7
5. Operation Procedure ..............................7
6. Battery Replacement ............................11
7. NOTICE ............................................... 12
8. Interaction of radiation with matter....... 13
9. End of life............................................. 15

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1. INTRODUCTION
This manual contains valuable information about
the nature of ionizing radiation that should be
understood by the user so that accurate
measurements can be made. Information on the
care of your Geiger counter is also included. If the
following instructions are followed, your radiation
monitor will give you many years of reliable
service.
The radiation meters are very sensitive pieces of
equipment. Although housed in a high –impact
case, the Geiger-Mueller tube that senses
radiation is fragile. If the unit is dropped, the G-M
tube may break. Exposure of the unit above 40℃
(100℉) may also cause the G-M tube to stop
functioning.
The electronic circuitry is sensitive to high
humidity(over 90%RH).

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2. SAFETY PRECAUTION
CAUTION
Take extremely care for the following
conditions while measuring
CAUTION
Please put the radiation monitor into a
plastic zipper bag before operating it
in a radiative contaminated area to
avoid radiative dust falling on the
monitor’s surface
Do not operate the meter under the
environment with explosive gas (material),
combustible gas (material) steam or filled
with dust.

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Do NOT put the unit in a very hot place(such
as a car, glove box, especially during
summer).
Do NOT allow the unit to get wet. However,
if it cannot be avoided, clean it with a towel
and allow unit to air-dry for several days(do
not place in an oven or microwave).
Do NOT back cover to bemoved only by
qualified service technician.internal
operating voltage is over 400VDC.
In order to avoid reading incorrect data,
please replace the battery immediately
when the symbol “ ” appears on the
LCD.
In order to avoid the damage caused by
contamination or static electricity, do not
touch the circuit board before you take any
adequate action.
Operating Environment: Indoors use. This
instrument has been designed for being
used in an environment of pollution degree 2.
Operation Altitude: Up to 2000M.
Operating Temperature & Humidity: 5℃~40
℃, 0%~ 80%RH.
Storage Temperature & Humidity: -10℃~
50℃, 0%~ 70%RH.

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3. SPECIFICATI
Display : 3 1/2 digits LCD with maximum
reading 1999.
Sampling :
10 second/ times(<20µSv/h).
1 second/ times(>20µSv/h)
unit selection :
µSv/h,µRem/h or mRem/h .
Measurement Range :
0.50µSv/h~1400µSv/h or
50µRem/h~140.0mRem/h
Alarm function : alarm set default
0.50µSv/h,can set 0~19.99µSv/h
Auto Power Off function : set time default
30 min, can set 0~60min;0 min disable auto
power off.
Low battery indication “”.
Power : 9V battery、NEDA 1604、IEC
6F22 or JIS 006P
Battery Life : About 50 hours(Alkaline
battery).
Over load display “OL”
Accuracy : ±20% (Cesium-137)
Energy dependency : 30KeV to 1.3 Mev
Weight : 220g.
Size : 143x74 x34 mm（LxWxH）

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4. IDENTIFYING PARTS
1. LCD display.
2. Setup function button.
3. Units and setup function down button.
4. Power ON / OFF button.
5. Unit and setup function up button.
5. OPERATION PROCEDURE
Press : All segment of the LCD
indicator is illuminated together with
BEEP signal for about two second. We
are now ready for testing.
Intermittent BEEP signal follows during
detection,auxliary radiation strength
sensing. The higher the repetition rate.

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Press : Select test unit µSv/h
Press : Select test unit µRem/h.
Press r more than 1 second to enter
setting alarm mode , the LCD display
“ALR”first the press the setting value, press
the ””or ””change the digit
value, Alarm the initial value 0.5µSv/h.
Press more than 1 second to enter
setting auto power-off(APO), the LCD
display “APO”first the setting value, press
the ””or ””change the digit
value, Auto power-off setting, the initial
value is 30 minutes.
Press more than 1 second to enter
setting buzzer ON or OFF ,the setting
default is always “ON”, the LCD display
“ON”or ”OFF”,press””or ””
change the ON or OFF.
Press more than 1 second to enter
setting calibration facfor, the LCD display
“CF”first the setting value,
press ””or ””change the digit
value, Calibration facfor the initial value
1.00.

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Press more than 1 second to exit
and return to measurment mode.
The Geiger-mueller tube is located behind
the slots in the upper edge of the case. The
surface of the tube is very thin .This allows
beta radiation to penetrate and to be
detected with greater efficiency. (Beta rays
and other types of radiation will be
discussed in the next section). This thin
surface is fragile and poking sharp objects
through the slots will damage the tube.
Your Geiger Counter is designed to be
sensitive to:
1. Gamma radiation (which includes X-rays).
2. Beta radiation.
Gamma radiation and X-rays can
penetrate the plastic case with
comparative ease.
Beta radiation can most efficently enter
the case through the slots. Although Beta
radiation is easily detected. It is difficult to
measure accurately. Therefore, when a
radioactive object is being searched for
Beta radiation, the open slots in the case
should be positioned in such a way that

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they are exposed to the object(see Figure
1).
(Figure 1)
If the unit shows a significantly higher
reading with increasing beep sound volume
in this position, you can be certain that the
object is emitting Beta radiation.
Now position the unit as shown in Figure 2.
In this position, where radiation cannot pass
directly through the slots (Beta radiation
travels in straight lines for the most part )
only gamma and X-ray radiation from the
object wil be detected.

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(Figure 2)
This is the position in which to hold the
geiger counter to take readings.
6. BATTERY REPLACEMENT
WARNING
If the symbol ” ” appears on the
LCD, please replace the battery
immediately
Use “－”form screwdriver to insert into
battery cover hole (OPEN).
Press completely screwdriver into battery
cover hole and fix it on slide of hole.
Push screwdriver towards the back and
remove battery cover out.

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EN-12
(Figure 3)
7. NOTICE
Geiger Counter to be accurate within
reasonable standards of acceptance, and
includes instructions that, if followed ,will yield
accurate measurements. Manufacturer
assumes no liability for damages, consequential
or otherwise that may arise from the use of the
Geiger counter by any person, under any
circumstances. The Geiger counter is sensitive
to gamma, beta and X-ray radiation, but not
necessarily to extremely low energy forms, or
alpha, neutron or microwave radiation. Do not
open Geiger counter or otherwise tamper with
or attempt to service it.

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8. INTERACTION OF RADIATION WITH
MATTER
The particles and photons that result from
nuclear decay carry most of the energy
released from the original unstable nucleus.
The value of this energy is expressed in
electron Volts, or eV. The energy of beta and
alpha rays is invested in the particles speed. A
typical beta particle from Cesium-137 has an
energy of about 500,000 eV, and a speed that
approaches that of light. Beta energies can
cover a wide range, and many radioisotopes
are known to emit betas at energies in excess
of 10 million eV. The penetration range of
typical beta particles is only a few millimetres in
human skin.
Alpha particles have even shorter penetration
ranges than beta particles. Typical alpha
energies are on the order of 5 million eV, with
ranges so short that they are extremely difficult
to measure. Alphas are stopped by a ~nin sheet
of paper, and in air only travel a few inches at
most before coming to a stop. Therefore, alpha
particles cannot be detected without being in
close contact with the source, and even then
only the alphas coming from the surface of the
source can be detected. Alphas generated
within the source are absorbed before reaching

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the surface. Due to short range, alpha particles
are not a serious health hazard unless they are
emitted from within the body when their high
energy, in close contact with sensitive living
tissue their high energy, in close contact with
sensitive living tissue, is an extreme hazard.
Fortunately, almost all alpha-emitting
substances also emit gamma rays, allowing for
their detection.
Neutrons, having no net charge, do not interact with
matter as easily as other particles, and can drift
through great thickness of material without incident.
A free neutron, drifting through space, will decay in
an average of 11.7 minutes, yielding a proton and
an electron (beta ray). The neutron can also
combine with the nucleus of an atom, if its path
carries it close enough. When a neutron is
absorbed into a nucleus, it is saved from its
ultimate fate (decay), but may render the nucleus
unstable. This absorption process is used in
medicine and industry, to create radioactive
elements from non-radioactive ones. Detecting
neutrons is specialized and beyond the scope of
typical Geiger counters, but most possible neutron
sources also emit gamma and beta radiation,
affording detection of the source.

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The highly energetic X-ray and gamma rays lose their
energy as they penetrate matter. X-rays have an
energy of up to about 200,000 eV, compared to
gamma radiation which can be as energetic as
several million eV. One million e V gamma radiation
can penetrate an inch of steel. Gamma and X-ray
radiation are by far the most penetrating of all
common types, and are only effectively absorbed by
large amounts of heavy, dense material of high
atomic number, such as lead.
9. END OF LIFE
Caution : this symbol indicates
that equipment and its accessories
shall be subject to a separate
collection and correct disposal

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TENMARS ELECTRONICS CO., LTD
6F, 586, RUI GUANG ROAD, NEIHU,
TAIPEI 114, TAIWAN.
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