GammaWatch.com
Personal Radiation Protection
New Model Coming Soon
GammaMaster FAQ
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GammaWatch.com Personal Radiation Protection
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New Model Coming Soon |
GammaMaster FAQ |
These FAQs still relate to the GammaMaster. A list of FAQs for the GammaWatch Basic will be added when available.
The Frequently Asked Questions (FAQ) page is divided into two main sections. The first is intended for people who are thinking about purchasing a GammaMaster and consists of general questions. The second section is intended for people who own a GammaMaster and the questions are in the form of "How do I ...?".
A printed users manual comes with the watch. Some people prefer the "How do I ...?" format over the format used in the manual.
General Questions
Can I use the GammaMaster for checking medical x-ray equipment?
Is there any guidance on how much radiation exposure emergency response personnel can receive?
How often does the GammaMaster need to be calibrated or source checked?
Owners Questions
Trouble Shooting
What does it mean when the line under the analog dose rate display flashes?
The digital watch is running faster than the analogue watch.
General Questions
What are the radiation units used by the GammaMaster?
The GammaMaster reports dose rate in µSv/h and cumulative dose in mSv. If you expose the watch to 1 µSv/h for 1 hour, the cumulative dose will be 0.001 mSv.
The Sievert (abbreviated Sv) is the internationally accepted unit for equivalent dose. There are 1 000 000 µSv and 1 000 mSv in 1 Sv. Historically, the units rem and R have been used. These can be converted to Sv as follows:
1 R ~ 1 rem = 0.01 Sv = 10 mSv = 10 000 µSv.
What type of radiation does the GammaMaster measure?
The GammaMaster is designed to measure the dose to the important organs of the body. [Scientists call this H*(10).] That means the unit measures gamma radiation, since alpha and beta radiation are not penetrating enough to reach vital organs unless the radioactive material is eaten or inhaled.
Gamma radiation is very penetrating and can cause harm even when you are not in direct contact with the source. The source does not even have to be exposed.
Most radioactive materials will have some gamma field, even if they also emit alpha or beta.
Can I use the GammaMaster for checking medical x-ray equipment?
No. x-ray machines emit short pulses of very high intensity (high dose rate) radiation. There is a limit to the dose rate that the GammaMaster can measure (please see our Technical Specifications page).
What is a "normal" dose or dose rate?
Most of us are exposed to about 1 mSv of gamma radiation per year. There is a large amount of variation in this exposure, depending on where one lives. Radiation exposure is typically greater in the mountain states than in coastal regions. Some of this exposure is due to radioactive materials inside our bodies and the rest of it is is due to external sources. The GammaMaster mostly measures gamma radiation from external sources.
Depending on where you live, your GammaMaster will probably read between 0.05 to 0.3 µSv/h.
The following table gives some typical dose rates that might be measured by the GammaMaster and their possible interpretation.
| Observed Dose Rate (µSv/h) |
Possible Cause | Action |
| 0.1 | Normal Background | |
| 3 | Flight on jet airplane | |
| 10 | Near a radium dial pocket watch | |
| 100 | On the side of a truck carrying radioactive material | Move away unless you have a reason for being there. |
| 1000 | Near high grade uranium ore | Members of the public should not be here. |
| > 2000 | Exposed artificial source | If you walk into a field this large, something is wrong. Members of the public should leave and let professionals handle the situation. |
It should be noted that radiation effects are related to total dose (dose rate times time) and not just dose rate. Very high dose rates can be managed by limiting the time spent in them.
At what level should I set the dose rate alarm?
The GammaMaster comes pre-set to alarm whenever the dose rate exceeds 0.6 µSv/h. This is a good setting for most people. It is high enough to almost eliminate false alarms but will indicate even small artificial sources.
Customs inspectors may want to set the alarm lower, to be more sensitive to smuggled radioactive material. People who routinely work with radiation will set the alarm at a higher level.
Whenever the battery is changed the dose rate alarm setting reverts to 0.6 µSv/h
At what level should I set the cumulative dose alarm?
The factory set cumulative dose alarm level is 9999 mSv. This will likely never be reached.
Cumulative alarms are usually used in occupational settings. Employers might set exposure guidelines (e.g. 0.1 to 1 mSv) for a specific task or per day.
Is there any guidance on how much radiation exposure emergency response personnel can receive?
US DOE and EPA have issued the guidance of 100 mSv (100 000 µSv) while protecting major property and 250 mSv while saving lives.
The GammaMaster uses an advanced algorithm to automatically adjust its response time between 2 seconds and 5 minutes. When the dose rate is a fraction of 1µSv/h, the GammaMaster averages the reading over several minutes to provide a more accurate reading. When the field is increased to a few hundred µSv/h, the GammaMaster will display the correct field within a few seconds.
With the audio turned on, the frequency of the beeps is the most immediate indication of the strength of the radiation field. The GammaMaster beeps whenever a gamma ray is detected.
How
often does the GammaMaster need to be calibrated or source checked?
The calibration of GammaMaster is not expected to drift over time and there is
nothing that can be adjusted.
Recommended calibration and source check frequencies depend on the intended use
of the GammaMaster. If you want to use the GammaMaster for regulatory
compliance, the time interval at which the calibration has to be checked will be
given in your local regulations. The regulations may also stipulate that the
calibration check has to be performed by an authorized lab.
Even though the GammaMaster is quite accurate, most customers will not use it
for regulatory compliance. We recommend that users expose the GammaMaster to
radiation once in a while, to assure themselves that the unit works. You can
purchase an inexpensive check source for that purpose or you can take the watch
to where you know the radiation level is elevated (for example on a jet).
Where can I get a check source?
The most easily available check source is a 20 kg (50 lbs) bag of potassium chloride. This is used as ice melter or water softener pellets and is available in grocery stores. Potassium chloride is not a strongly radioactive material, so a large quantity is needed and it will take the GammaMaster a few minutes to respond. If the GammaMaster is placed directly on top of a 20 kg (50 lbs) bag of potassium chloride, it will read about 0.2 to 0.5 µSv/h above background.
Ebay is a good place to get material that is more convenient to use to check the response of the GammaMaster. We have purchased some materials to evaluate their suitability as a check source.
Uranium doped glass marbles. These do not work very well. They do not give off enough gamma radiation to easily see a response above background radiation, even when you use a lot of them.
Thorium mantle for camping lanterns. The mantles that are sold in stores now usually do not contain thorium. The thorium mantles offered on Ebay will make the GammaMaster respond, especially if you put a few of them together. A health concern could be that the mantles look like cloth and the radioactive material could probably be dispersed if a pet decided to chew on one.
Uranium ore or mineral sands. This will make the GammaMaster respond, depending on quantity and grade. Again the problem is that the material could be dispersed.
Radium dial watches. Some of these are quite radioactive. You can see the GammaMaster respond to a radium dial pocket watch on our Pictures and Video page. The radium paint is old and can flake off, again causing the radioactive material to be dispersed. Some watches that are sold as "radium dial" are really not and are not radioactive.
Thoriated TIG welding electrodes. These work well as check sources. They are solid metal rods (tungsten with 2% thorium), so the material is not easily dispersed. Of course, the larger the diameter of the rod is, the more radiation is given off.
For those customers who don't want to hunt for sources on ebay, we sell a 2% thoriated TIG welding electrode broken into pieces and encased in plastic for $ 20.00. By having the electrode incased in plastic, the possibility of dispersing the material is reduced.
We are only making these sources available to GammaMaster customers and only in the US and Canada. Shipping is included in the price. After you have made your GammaMaster purchase, you will be given the option of purchasing a check source. Those customers who have already purchased a GammaMaster from us should contact us by Email to order a check source.
Our sources are sized so that they will make the GammaMaster read between 1 µSv/h and 5 µSv/h, if the source is held to the back of the watch. At the distance of 1 m, the gamma field is not measurable above background.
Do I need a license to have radioactive electrodes?
No. Up to 4% thoriated tungsten is exempt from NRC licensing requirements in the US under 10CFR40.13. In Canada the Nuclear Safety and Control Act does not apply to naturally occurring radioactive materials (thorium) that are not associated with the production of nuclear energy.
The fine print: This is our best understanding of the regulatory requirements. We make no warranty that this interpretation is correct. The responsibility of complying with local regulations remains with the user.
Is the size and weight of the watch practical?
Please refer to the Technical Specifications for the size and weight. The size given there includes the crown, the buttons and the part of the case that the band attaches to.
To get a better feel for the size of the unit, please look at one of the pictures, either on the navigation bar or on the Pictures and Video page. The diameter of the crystal is 3 cm. This is the same size as the crystal on a Rolex Oyster Perpetual and other fine gentlemen's watches.
The height of the watch ( 2 cm ) is larger than most other watches. The watch does not look awkward or pretentious. In fact, many people spontaneously comment "Nice watch!". These are people who do not know that there is anything special about the watch.
Most people will comment on the weight, when they first pick up the watch. With the stainless steel wrist band the watch weighs 170 g. Without the band it weighs 95 g. Some people find it heavy, others say it has a solid, quality feel.
The watch comes with a spare rubber wrist band, which is lighter than the stainless steel one. Customers could of course use any type of strap that they wanted (e.g. cloth). Most people get used to the weight in a day or so and use the GammaMaster with the stainless steel band. It is a matter of personal preference.
Sorry, the GammaMaster is not available in a ladies version.
What are the details of the warranty?
The GammaMaster is warranted for a period of one year from the date of original purchase against defects in either material or workmanship. We will repair or replace the unit, at our option, if the unit proves to be defective. This warranty does not cover batteries or normal wear on the bracelets, crystals or cases. This warranty does not cover accidents, misuse or neglect and is void if the watch has been opened or taken apart, except for battery changing by a qualified watch repair shop or jeweler.
We also guarantee that the description of the GammaMaster as given on this website is essentially accurate.
PLEASE NOTE: You must contact us by Email and obtain instructions on how to complete the customs documentation, before you return any product to us. Shipments that have not been authorized by us, or where the documentation has not been completed to our specifications, will be refused. (We have to do this because incorrectly documented returns can cause huge customs charges.)
Shipping and handling charges for warranty claims:
If the GammaMaster is found to be defective on initial inspection, we will refund your shipping cost for returning the watch to us. (The shipping cost refund is limited to $ 15.00 for overseas shipments.)
If the GammaMaster is found to be defective at a later date within the warranty period, you pay the shipping cost for returning the watch to us and we will ship the repaired unit back to you at our cost.
Where can I get more information?
For
specific information about the GammaMaster please see the Technical Specifications or contact us at questions@GammaWatch.com
.
For an overview of major radiation accidents compiled by the International
Atomic Energy Agency see Lessons from Major Radiation Accidents
.
For
scientific information about radiation please go to the Health
Physics Society .
For
an extensive list of radiation related info, organized by region and country, try Nick's
World Collection of Radiation Links .
Owners Questions
How do I shorten the metal wrist band?
You can remove links from the band. There are arrows on the links to indicate the direction in which the pins come out.
Put the watch band on its side on a piece of rigid Styrofoam insulation. Use a blunt pin and a small hammer to drive the pins out of the watchband and into the insulation.
Remove excess links and push a pin back in to reconnect the wrist band.
Alternatively, you can take it to a watch repair shop. They have special tools that hold the band in place and let the pin come out.
The GammaMaster is a sensitive instrument and battery replacement should be done by a watch repair shop. Please save these instructions and take them to such a shop when you need to have the battery replaced.
The radiation detector and digital watch use a CR2032 battery and the analogue watch uses a SR 621 SW (or 364) battery.
To Replace the Batteries:
The life of the CR2032 is about 9 months, but can be shorter if higher than average radiation levels are measured. The life of the SR 621 SW battery is about 2 years.
Remove the back cover.
Remove the contact plate by carefully moving the clip near the top of the watch with a screwdriver. Make sure you don’t break off the plastic tab that the clip locks on to. It is a good idea to examine the locking mechanism under a magnifying glass before trying to open it. (Do not remove the insulating foil from the plate.)
Remove the old CR2032 battery.
The SR 621 SW battery is located under the CR2032 battery.
Remove the old SR 621 SW battery if required.
Replace the SR 621 SW battery if required. (+ faces you)
Replace the CR2032 battery. (+ faces you) Be careful not to bend the gold spring.
Replace the contact plate. Be careful not to bend the gold spring.
Replace the back cover. It is a good idea to use some silicone lubricant on the rubber O-ring.
Press the reset button for 2 seconds and release. This should turn on the test mode: The watch will beep and all items on the LCD display will show. After that, the watch will return to dose rate mode. It will take 6 minutes before a non-zero dose rate is displayed.
If pressing "reset" does not turn on the test mode, make sure that the CR2032 battery is inserted properly and that the gold springs are not bent.
The microprocessor is somewhat sensitive to voltage jitters, especially while the battery is being changed. If the reset button does not work or if the display looks strange, you may have to press the backlight button while the CR2032 battery is removed in order to completely discharge any capacitance.
How do I display the current dose rate?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows µSv/h. The current dose rate is now displayed.
How do I see what the dose rate alarm threshold is set at?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows µSv/h.
Push the Select button. The dose rate alarm threshold will now be displayed for a few seconds. After that, the display will go back to the current dose rate.
How do I set the dose rate alarm threshold?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows µSv/h.
Push and hold the Select button for about 2 seconds until SET appears above the µSv/h.
Push the mode button. This will move the decimal point of the alarm setting. (You should see the decimal point flashing.)
If you want to quit after moving the decimal point, press select again for 2 seconds until SET disappears. (Alternatively, you can leave the watch alone for 1 minute and SET will disappear.) To change the digits do the following:
Push the select button. Now the first 2 digits should be flashing.
Push the mode button to change the value of the digits.
Push the select button. Now the second 2 digits should be flashing.
Push the mode button to change the value of the digits.
Press select again for 2 seconds until SET disappears. (Alternatively, you can leave the watch alone for 1 minute and SET will disappear.)
How do I display my cumulative dose?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows mSv. Your cumulative dose since last reset is now displayed.
How do I see what the cumulative alarm threshold is set at?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows mSv.
Push the Select button. The cumulative dose alarm threshold will now be displayed for a few seconds. After that, the display will go back to the cumulative dose.
How do I set the cumulative dose alarm threshold?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows mSv.
Push and hold the Select button for about 2 seconds until SET appears above the mSv.
Push the mode button. This will move the decimal point of the alarm setting. (You should see the decimal point flashing.)
If you want to quit after moving the decimal point, press select again for 2 seconds until SET disappears. (Alternatively, you can leave the watch alone for 1 minute and SET will disappear.) To change the digits do the following:
Push the select button. Now the first 2 digits should be flashing.
Push the mode button to change the value of the digits.
Push the select button. Now the second 2 digits should be flashing.
Push the mode button to change the value of the digits.
Press select again for 2 seconds until SET disappears. (Alternatively, you can leave the watch alone for 1 minute and SET will disappear.)
Note that changing the cumulative dose alarm threshold will re-set the cumulative dose to 0.000.
How do I re-set the cumulative dose reading to zero?
Changing the cumulative dose alarm level will zero the cumulative dose. Also, changing the battery or pressing the reset button will return the cumulative dose to zero.
How do I display the current time?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows a stylized watch. The time is now displayed.
How do I see what the daily alarm is set at?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows a stylized watch. The time is now displayed.
Push the Select button. The alarm time will now be displayed for a few seconds. After that, the display will go back to the current time.
How do I activate or deactivate the daily alarm?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows a stylized watch. The time is now displayed.
Push the Select button. The alarm time will now be displayed for a few seconds.
While the alarm time is being displayed, push the mode button. The alarm indicator will appear/disappear.
How do I see the current date?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows a stylized watch. The time is now displayed.
Push the Select button. The alarm time will now be displayed.
Immediately push the select button again. The date will now be displayed for a few seconds in DD MM format. After that, the display will go back to the current time.
How do I get the seconds to display?
Identify the Mode and Select Buttons.
Push the mode button a few times until the display shows a stylized watch. The time is now displayed.
Push the Select button. The alarm time will now be displayed.
Immediately push the select button again. The date will now be displayed for a few seconds in DD MM format.
Immediately push the select button again. The minutes and seconds will now be displayed in mm:ss format.
Push select to return the unit to the hour:minute display.
How do I set the current time, date and daily alarm?
Identify the Mode and Select Buttons.
Press the mode button a few times until the timekeeping mode is selected and the clock symbol is shown.
Press and hold select for 2 seconds until “SET” appears over the clock symbol. The first 2 digits (hours) of the daily alarm are now flashing. Pressing the mode button will change the value of the flashing digits.
Press select. The second 2 digits (minutes) of the daily alarm are now flashing. Pressing the mode button will change the value of the flashing digits.
Press select. The second 2 digits (seconds) of the minute:seconds display of the current time are now flashing. Pressing mode will set the seconds to 00 (this makes synchronizing watches easier).
Press select. The second 2 digits (minutes) of the hour:minute display of the current time are now flashing. Pressing mode will increase the minutes by 1.
Press select. The first 2 digits (hours) of the hour:minute display of the current time are now flashing. Pressing mode will increase the hours by 1.
Press select. The first 2 digits (day) of the day:month display are now flashing. Pressing mode will increase the day by 1.
Press select. The second 2 digits (month) of the day:month display are now flashing. Pressing mode will increase the month by 1.
Hold select for 2 seconds to exit the setting sequence.
How can I improve the accuracy of the digital watch?
The digital watch is intentionally made to run a little bit fast (about 5 seconds per day). This allows the user to adjust the accuracy of the watch and results in more accurate timekeeping.
You will need to measure and note how many seconds the watch gains per week. Once you have that value, do the following:
Identify the Mode and Select Buttons.
Press the mode button a few times until the timekeeping mode is selected and the clock symbol is shown.
Press select. The daily alarm is now displayed.
Immediately push the select button again. The date will now be displayed for a few seconds in DD MM format.
Immediately press and hold select for 2 seconds until "SET" appears. You are now in the accuracy adjustment mode. (Only 2 digits are shown.)
Enter the number of seconds per week that the watch is fast by pressing the mode button.
Press select when done to return to the current time display.
How do I set the unit so it emits a tone every time a gamma ray is detected?
The digital dose rate display takes some time (2 seconds to 6 minutes depending on the dose rate) to respond to changes in radiation levels. To locate the source of radiation, a more immediate feedback is often desired.
By pressing and holding the mode button for 2 seconds the audio mode is turned on/off. In this mode, there is no delay. The unit emits a beep whenever a gamma ray is detected. The more frequent the beep, the closer you are to the source of the radiation.
Trouble Shooting
What does it mean when the line under the analog dose rate display flashes?
This is the first indication that the battery is low. In this state, the audio does not work.
The alarms do not work and there is no audio. Why?
Check if the thin line under the analogue dose rate indicator is flashing. This is the first indication that the battery is low. In this state, the audio does not work.
The unit is stuck in mSv mode and I cannot switch modes.
This is the second indication that the battery is low. The unit defaults to this mode, so that you can record your cumulative dose before changing the battery.
The digital watch is running faster than the analogue watch.
The analogue quartz watch is factory set to be accurate. The accuracy of the digital watch can be adjusted. Click here to find out how.
