Barometer and atmospheric pressure. Barometer - a device for measuring atmospheric pressure
Types of barometers: A mercury barometer consists of a tube filled with mercury and a container of liquid. One end of the tube is sealed, and the other is lowered into the liquid. The aneroid barometer does not use liquid, a corrugated box with slightly diluted air acts as a sensitive element in it. This box changes its size a little depending on atmospheric pressure; these changes are displayed by an arrow attached to it by means of sensitive springs. Aneroid barometer can often be found in everyday life, beautifully designed, it can serve as an unusual gift, not only beautiful, but also useful, especially for a weather dependent person.
Measurement method: If you have a home barometer, measuring atmospheric pressure is not difficult. You just need to look at what division the arrow indicates, often on home barometers there are additional notations “clear”, “variable”, “rain”. Moreover, there are barometers with 2 arrows - one of them is movable and indicates pressure, and the second can be moved independently. By setting it in the area indicated by the moving arrow, after a while you can check the reading of the device and understand the pressure rises or falls. It is more difficult to determine the level of atmospheric pressure without a barometer. To do this, you can observe the sparks from the antennas of the tram or trolley, at high pressure the sparks will be bright blue, and at low they will be slightly greenish. In nature, you can take advantage of a coniferous tree branch. To do this, remove all the needles from it except one, then fix it vertically on the plank and observe. When the weather is clear, the needle will rise and fall in the rain. However, it is still more convenient to have a ready-made device on hand.
The benefits of measuring atmospheric pressure: You can not say that it helps meteorologists predict weather. First of all, the readings of atmospheric pressure are needed by weather-dependent people. The pressure level begins to change before the weather changes, which means that by observing the pressure variable you can prepare for possible health problems. People with cardiovascular diseases, hypotension and hypertension, migraines and other diseases react to the weather. Timely taking the necessary drugs will reduce the risk of exacerbation of the disease during a changing weather.
The level of atmospheric pressure is not the indication that the announcer lists while broadcasting the weather forecast on TV or radio. These are indicators that can significantly improve the quality of life for you and your relatives if you understand them and monitor the change in pressure. In the end, pressure reduction information may prompt you to take an umbrella with you.
Before using the device for the first time, or when moving over long distances, you must calibrate the device.
Thermometer: measures the current temperature, calibration is not required. Since the device is small, it quickly heats up due to the heat of hands, body, and sunlight, and the readings of the thermometer in this case may be higher. To measure the current temperature, wait at least 5 minutes for the device sensor to accept the ambient temperature.
Weather forecast: based on changes in atmospheric pressure, temperature and humidity over the past hours and days (depending on device model). In some models, it is necessary to set the current value of the weather from four possible: “Sunny”, “Partly cloudy”, “Overcast”, “Rain”. Next, the device accumulates data and predicts the weather. It is recommended to install (correct) a weather forecast on a sunny day. An accurate weather forecast for the next day will be displayed a few days after the device accumulates data.
Barometer: measures relative atmospheric pressure.
Normal atmospheric pressure at 0 ° C is 760 mm Hg. Art. or 1013 hPa.
750 mmHg Art. equal to 1000 hPa
1 mmHg Art. equal to 1.333 hPa.
Atmospheric pressure decreases as altitude or temperature increases.
At a temperature of 0 ° C and a pressure of 1000 hPa, the pressure step is 8 m / hPa. That is, when rising by 8 meters, the pressure will decrease by 1 hPa.
At a temperature of 0 ° C and a pressure of 1000 hPa, the vertical baric gradient is 12.5 hPa. That is, when climbing 100 meters, the pressure will decrease by 12.5 hPa.
When the temperature increases by 10 degrees, the pressure decreases by 3.7 hPa.
On average, at low altitudes, every 12 m of rise reduces atmospheric pressure by 1 mm Hg. Art. At high altitudes, this pattern is violated.
Since atmospheric pressure depends on altitude, for example, in the case of the same state of the atmosphere, the values \u200b\u200bof atmospheric pressure in Moscow and St. Petersburg will differ due to the fact that these cities are located at different heights. In Moscow, located at an altitude of about 156 m above sea level, the pressure will be approximately 15 mm. Hg. Art. lower than in St. Petersburg, located at an altitude of about 4 m above sea level.
Altimeter: measures barometric height. With your constant position on Earth, when the atmospheric pressure and temperature change, the altimeter readings can vary up to 20 meters during the day.
The altimeter displays relative and absolute altitude. You can reset the relative height level to 0 meters. Absolute altitude is displayed from sea level. It can be adjusted in two ways:
1) By setting the absolute height in the altimeter settings manually;
2) By setting the pressure at sea level in the barometer settings from weather reports, for example, from the sites:
http://meteo.paraplan.net/forecast/summary.html?place\u003d3800 (pressure in hPa)
http://rp5.ru/Weather_in_St. Petersburg (pressure in mmHg)
Compass: shows the direction to the north pole. It is necessary to calibrate the compass by slowly rotating it around its axis in calibration mode on a horizontal surface in the absence of strong magnetic fields, so that the compass determines the north magnetic pole Nm. So that the compass shows the direction to the north geographical (true) pole N, you need to set the magnetic declination in the city you need. Magnetic declination is the angle between the geographic and magnetic meridians at a point on the earth's surface. For St. Petersburg, the magnetic declination in 2015 - 2019 is approximately equal to + 11 ° E. The magnetic declination constantly changes by a fraction of a degree every year.
For any point on the Earth, you can determine the current magnetic declination at http://www.ngdc.noaa.gov/geomag-web/#declination
All liquid and digital compasses display the direction to the Earth’s magnetic pole, and when working with them, magnetic declination must be taken into account to find out the direction to the north pole. GPS and digital compasses can show the direction to the true north pole.
Pedometer: measures the number of steps taken, distance and calories burned. In the pedometer settings, you must set the stride length and your weight. The pedometer determines the fact of taking a step on the negative acceleration of the human body at the moment the foot touches the ground, which is recorded by the accelerometer sensor. The pedometer correctly counts the steps, if you strengthen it in the correct position in a certain place, usually on a waist belt or wrist. Accuracy is highly dependent on the location of the pedometer and the particular gait of a particular person.
Periodically check the device settings and adjust them in accordance with the current settings.
A barometer is a device that continuously displays atmospheric pressure. Its basis is an aneroid - a sealed container filled with some kind of gas. When atmospheric pressure changes, the geometric dimensions of the aneroid change. This, in turn, makes the arrow move.
You need to set up a barometer if its readings differ from those of the local weather station by more than 8 millimeters of mercury (mmHg). Usually an adjustment screw is provided at the rear of the housing. Turn this screw (but at an angle of no more than 45 degrees!) Until the arrow indicates the correct pressure.
Reference: 1 hPa (hPa, hectopascal) \u003d 0.750062 mm. Hg. Art. If both numbers are multiplied by 1000, it turns out that 1000 hectopascals are equal to 750 millimeters of mercury.
Electronic pressure transducers are integrated into telephones. You can read an article about why it is needed in smartphones.
Andrey 04/18/2009 9:44 p.m.
I bought a BARO barometer. I wanted to take it apart - it turned out that it was not separable. The arrow is walking tight - I wanted to lubricate.
Rio 04/21/2009 16:57
Nothing, over time, the arrow breaks in!
Leonid 04/27/2009 09:34
In the store I watched "Cliffs." They were whipped up. The difference in readings was about 20 mm. Hg. pillar. Therefore, after the purchase, be sure to check them with the standard or with the radio station.
Victor 04/05/2014 00:07
Hello Leonid, I also bought a UTES, but I have doubts whether it works correctly or not. You write that you can check with their standard or radio station. Sorry, Leonid, how is this done? Sincerely, Victor.
Evgeny 02/28/2010 08:10
I bought the Zvezda barometer from Uglich, showed 760 mm, we had 749 mm — let me down, the next day the pressure increased to 753 mm (showed an excellent increase), after 2 days the pressure dropped to 743 mm, and on mine 753 mm left - is it buggy?
Konstantin 02/28/2010 23:22
Eugene, try to lightly tap the glass with your nails so that the arrow moves. And then the new instances have such a problem that the mechanism is “not run-in”.
puch 04/17/2010 12:04
In fact, earlier in the instruction it was indicated that it was necessary to lightly tap it on the body. I will not go into details of the design, but even AVIATION BAROMETERS are tapping on the glass - there is an INSTRUCTION about this in the description of the device !!!
Vyacheslav 11/27/2012 10:02 PM
Why do I have a UTES BTK-SN-14 barometer almost always showing “Variable” for two months already? The arrow moves to the right, then to the left, but on the marking “Variable” and only once showed “Wind”. I have suspicions for the reason that it rained almost every day during these two months, and the arrow never reached the marking “Rain”. Please reply to email mail: [email protected]
novel 03/26/2010 10:06
Hello. why do we need an arrow mounted on the glass? thanks.
cook 03/27/2010 18:50
why, in order to fix values \u200b\u200bfor yourself and see the difference between them 😉
albert 04/10/2012 20:36
look at the difference, for example, between the first and second day.
narod 06/18/2010 09:51
Thanks for the tapping instructions, I also wanted to take it to the store, although I tapped it. we will wait until it is rubbed 😉 and whoever has not bought it, BUY. You can adjust yourself: for several weather information sites, choose the average. we have a fishing barometer, 5+
Marina 07/08/2010 13:34
I have a German barometer, after she fell into the hands of a small child, stopped showing anything, who knows if it can be repaired?
Natalia 11/14/2010 13:57
Please help, I bought a barometer as a present, while it’s far from my birthday. They hung it on the wall, decided to check if it works, and adjusted it as it was written in the instructions. For 3 days now, it’s been hanging, and the readings have not changed, although there was a sharp pressure drop.
Nikolai 11/20/2010 10:19 PM
Natalia, it’s possible that until it is developed, try gently tapping the case with your fingers. My first, too, behaved this way, and after a while he stirred, now he reacts to 1 mm. Hg. Art.
Sergey 12/28/2010 17:20
Tell me, I need advice, where to hang it correctly: on a sunny wall or in the shade? Or to the window? Thanks in advance.
Gosh 12.12.2010 20:18
Sergey, hang it on a wall on which the sun's rays do not fall.
Victor 11/27/2011 20:12
Remember, great barometer! there is no difference where to hang it absolutely. The main thing is not to lower it in water, and knocking on it is not recommended.
P16 01/29/2017 01:41
you don't know anything about barometers
Alexander 05/07/2014 15:08
I heard that a barometer needs to be hung on the wall that faces the street (cold), tell me, is this true?
Grisha 05/07/2014 20:50
I believe that sunlight should not fall on it. And on which wall the barometer hangs, it is not critical, because the temperature of the walls differs by a degree or two, and the sensitivity of the barometer does not suffer from such a small temperature difference.
Nata 11/06/2011 21:26
And after what time did you get agitated? Mine only works after tapping, but I really want it to work already.
Goldfinch 11/07/2011 00:20
I started to work independently on about a year later. tapped glass every day before.
Timur 12/07/2010 12:34
But you can still drip oil on the axis of the arrow !? To move easier! I have a school instructional BR-52, I knock on the instructions! There is a difference with the Internet! But, I think, the terrain affects (mountainous), I live on the third floor, in theory, it should also influence. In Soviet times, the quality of barometers was better, the body was metal, etc., it was more solid!
Pavel 02/06/2011 17:28
The device worked fine. Then on the back panel they tightened the bolt all the way. How to configure it now? Thanks in advance.
t_suslova 04/01/2011 07:29
We were presented with a German barometer, and his school starts at 950. How to set it up correctly if we are 900 m above sea level? In our area, the pressure does not exceed 700 mm. Hg. Art.
Alexey 06/05/2011 09:50
950 is not millimeters of mercury, it is hectopascals, 950 hPa is 712 mm of mercury. Art.
Max 08/14/2011 16:55
There are two barometers: one stationary, the second in gps, in gps in the settings there are two parameters: barometric pressure and atmospheric, what is the difference? The first value is adjusted, and the second is not, what is it for?
Lilya 09/10/2011 13:14
How to transport a barometer by plane, take it to a cabin with hand luggage? and what will happen to him during the flight? and how to configure it later? share your experience ...
nikolai 09/26/2011 11:50
Thanks to all the specialists who wrote that you need to tap on the glass. I bought the device in another country with instructions in English. pressure drops - the arrow stands still until you knock. I thought that it was faulty, you could not return it back, and I calmed down straight. while the arrow will rub, I will tap on the glass.
Gennady 10/12/2011 20:14
Help me to understand! I have two rows of numbers on the barometer. Now, for example, the pressure is 755 mm. I only have numbers from 80 to 102, sort of. How is this to be understood? And then the device is cheap, the instruction is in English. In short, can throw it out? But he reacts to something, but the arrow practically stands still. Help me please. Thanks in advance.
apexander 11/06/2011 16:06
flew by plane for 8 hours. was bl in hand luggage. unpacked, arrow dug up, even knock on glass. twisted the adjustment screw on the back, you can scrap.
Alex 03/29/2012 09:36
Typically, the instructions are as follows: IT IS FORBIDDEN TO CARRY A BAROMETER BY AIR TRANSPORT.
Now in repair.
Sergey 04/02/2012 11:15
It is absolutely forbidden to transport by plane. The barometer is not designed for such overloads. The membrane may become deformed or depressurized or the thread may break. After an airplane, repair is useless. It’s easier to buy a new one.
Sergey 11/29/2011 15:56
The main problem of the error in the readings of aneroid barometers is your geographical location, for example, Astrakhan and Pyatigorsk. Pyatigorsk is much higher, respectively, less pressure is applied to the aneroid at maximum atmospheric fluctuations. Therefore, the device will “lie”. In this case, you need to change the size of the scale and adjust. In the case of Astrakhan, the opposite is true. Manufacturers do not indicate the working ranges of heights for devices, it is sad, but fixable - you have to modify and adjust.
Ksenia 02/08/2012 09:47
Good day! Please help me set up the barometer, it’s about 50-60 years old, if not more, what needs to be done with the two hands so that they show all these pressure drops, etc.? at what value of the digits should they be combined and what to do next?
Anastasia 02/14/2012 17:57
I bought a barometer, several weeks have passed, and the readings do not change, the arrow does not move by one division. Is he not a worker? Tell me please.
Sergey 03/02/2012 09:34
The same trouble. The pressure dropped by 20 mm. Hg. Art., and the arrow stands in one place. And another such situation: when you try to adjust the arrow goes sharply left or right. So it should be, or should it move smoothly?
Irina 02/29/2012 19:14
The cat, the cattle, dropped BAMM-1. Shows not that. I wonder if you can align or everything, in the trash?
Andrey 03/17/2012 12:49 PM
I bought a fisherman’s barometer pb1 on February 23. Hung on the wall. the arrow does not deviate until you tap on the glass. Changed to another, and then another to a third. At all devices the arrow stands still. you need to tap on the glass, but not hard. I won’t change anymore. tired of it. The seller does not really explain.
Alex 03/29/2012 09:32
Yes, that is right. This is a feature of the mechanism of the barometer, because the showing (working) arrow is not fixed rigidly, but through suspensions and a mechanism that increases the stroke. The barometric box has a very small stroke (compression, expansion) when the pressure changes, not visible to the eye. Therefore, a mechanism was made there that allows transferring movement to the arrow from the smallest movements of the box, which can already walk on a scale of 30-40 cm, as well as the power of the barometric box itself is not enough to move the arrow to a large distance.
Alexey2 04/16/2012 00:09
I hung in the kitchen for three years, everything was ok, I recently noticed that the arrow fell and shows constantly 800. It feels like it just lies and does not move. He took off, shook in different directions - the arrow goes either left or right. If anyone can tell what to do, I will be very grateful. In our city there is no repair of the barometer.
Olga 04/18/2012 3:22 PM
Tell me, please, I bought a "cliff" with arrows. From what I read, I realized: you need to knock on the glass, and which one indicates atmospheric pressure, black or the one that moves (gold)? For example, today it’s raining, but it shows me that it’s variable.
Victor 05/24/2012 10:01 PM
Black indicates pressure.
Alexander 06/21/2012 11:07
Hello! acquired the UTES BTK-SN-14 barometer; I live in Zheleznovodsk (near Pyatigorsk). so, the arrow is constantly where the rain is, regardless of what the weather is like on the street, the pressure changes from 700 to 718 (just the range where the rain is drawn)! Tell me, what should I do to show the appropriate weather?
Misha 06/21/2012 19:41
What weather pressure do you have? If the readings correspond, then you have to choose - either characters or numbers.
alexander 06/23/2012 10:12
to us in Kamchatka only a plane. so it turns out figs to you, and not a working device?
Victor N 01/05/2015 09:06
Put the barometer in a pressure cooker, tighten the lid tightly and seal the discharge tube, or in any pressure tank. About 15-17 years ago, he moved by plane from Kiev to Surgut, and then from Surgut by helicopter to Purpe. The arrow was developed, probably, after the helicopter, there is no need to tap it anymore, it began to lie 3-4 mmHg, corrected by a screw.
Evgeny 07/02/2012 22:42
I bought a cliff BTK-SN-14, at first I lied at 10 mm RT. Art., that is, if we have 750, it shows 760, tightened the screw, set according to the weather station. Change reluctance, I like the design itself. But the hunt is for him to show accurate data. Otherwise, it will be necessary to sort it out, there is a post where the reason is indicated - poor assembly quality of the mechanism. It is treated with your own hands, by the method of sorting the mechanism and setting it up. But it's a shame.
Holy 10.10.2012 11:53
Good day! I bought a barometer “RST04460 weather forerunner”, the saleswoman said that it needs to be activated (turn the screw back 90 degrees), which she did. Are her actions right? or take her back?
Holy 10/27/2012 1:33 p.m.
In short, I took this barometer back and exchanged ATP for the German, it seems that all the problems went away right away, put pressure on my region, it showed no problems. BOMB!!!
Alexander 01/27/2017 18:05
Hello! Could you write more precisely what kind of German ATP? I am looking for a German barometer, I live in the countryside, you can only buy on the Internet.
Michael 11/03/2012 17:02
: bad: Hello. Tell me, I set up the device according to the weather station of my region, 148 mm is normal pressure in our region, and at this pressure it rains and overcast. The device must also display below pressure. Please explain.
lydia 01/22/2013 19:01
How to configure, tell me. On TV channels and sites show different pressure. The difference is from 10 to 30 mm. Hg. Art.
Alexander 09/18/2013 11:45
Firstly, the barometer itself is inaccurate. Secondly, it does not work well (no stability, low sensitivity, sticks, strains when tapped, etc., etc.). About the difference in readings. Even if you were not too lazy and brought your barometer to the local weather station and there you tuned it to the same readings as theirs, and then brought your barometer home for example to the 10th floor of your “chicken coop”, called back to the same weather station and clarified the pressure readings at this point in time and found the difference in the readings of your barometer and weather station, this does not mean at all that the barometer is not working. The rule works here: each increase of 10.5 meters in height gives a fall of 1 mm Hg. (torr) and back. Therefore, if you have a constant difference in readings with a local weather station, for example, 5 mmHg. and you set up your miracle machine there and it works stably, then you can estimate that your shelter is a fortress on the 10th floor with a stable difference compared to a local weather station, for example, 2 mm Hg. is at a height of 2 x 10.5 \u003d 21 meters. relative to the local weather station.
A height difference of 21 meters gives a pressure drop of 2 mm Hg. This is a permanent correction for your location.
You still do not feel like a celestial? : love:
Alexander 02/18/2013 17:43
they presented the BTK-SN-17 barometer, tried to set it up, the adjustment course of 45 degrees is not enough, what should I do? return?
Sergey 03/07/2013 11:40
I see: the children on the ice made football from some device. Took and brought home. BM-2. Made in USSR. The humidity arrow is gone. I cleaned everything, read the sites, “sat” and adjusted. It seems to show (resuscitated). I have long dreamed of having a barometer.
Konstantin 03/11/2013 00:30
I bought a weather station "Kruzenshtern 16" RST05116. Initially, after the purchase, the pressure showed 735 mm Hg. Art. Learned the real pressure in our area. Using the adjusting screw set the current 750 mm RT. Art. For three days, the pressure on the barometer has not changed. The arrow stands rooted to the spot. Although the pressure in the city has changed (dropped by 8 mm).
What is the problem? Malfunction?
Michael 03/18/2013 18:22
I think that the mechanism has not yet been worked out. Tap softly on the glass with your fingernail; the arrow should move. If the pressure has really changed significantly, and the arrow does not move after a knock, then you must take it under warranty. Good luck to you!
Konstantin 03/19/2013 17:30
Michael, the arrow moves after a knock. And set to the desired pressure. But why doesn’t she want to move herself? If this is a mechanism, how much time will it be earned?
Michael 03/19/2013 20:52
Konstantin, my “BARO” device was run in, probably, for 2-3 months. All this time I tapped on glass every day. But over time, everything became normal. Now he is 5 years old, he reacts to changes in a fraction of mm. Hg. Art. So be patient.
Konstantin 03/20/2013 08:19
Michael, noticed that the arrow started to work on increasing. I was even delighted. But when the pressure began to fall, the arrow did not respond. I had to knock. And I pounded not only on glass, but also on the back of the device. After that, the arrow rose to its intended value. Is this the norm? Why is the arrow already moving up, but does not want to go down yet?
Michael 03/20/2013 17:29
If she moves up, then there is already a result! Do not worry, over time everything will work as it should. Just the efforts of the membrane and the spring are not enough to overcome the friction force of the mechanism. I will not advise you to lubricate. Just wait.
Konstantin 03/20/2013 18:51
Thank you, Michael, for your advice. I will wait.
Konstantin 03/18/2013 08:30
And in response to silence ... If only someone would advise something.
Victor 06/04/2013 23:09
Tell me, but can it be transported in a car (well, for example, to a summer residence, in a village, or just with a tent for nature) and is it necessary to constantly adjust them?
Natalia 07/15/2013 09:43
I bought a device for myself, it has a barometer, a thermometer, a hygrometer and a clock, the production of Uglich and all this costs 2050 p. I was not happy for a long time, because I realized that the barometer was not working (I bought it only because of it), I went to the store a week after the purchase, the seller: “Write a statement”, etc., and I say that I need the device, and not the refund, then it was replaced, it came home - it turned out that the watch did not work for this instance (the barometer, as you taught, reacted when tapped), it went changed to another watch (they are easily rearranged). I honestly watched the new one for three more days - the arrow faithfully stands where you put it; if you move it, it stands there, it does not move itself. She told the seller when the watch was changing that the next time I would come for the money. But I need a device. I tapped it, lives on its own wave, if it moves, it’s not in the right direction. Tell me how to be? Maybe another advise? In our city, few people sell them.
Alexander 07/17/2013 11:41
I read a few comments, my hair stands on end ... The impression is that people are completely unfamiliar with such a thing as atmospheric pressure, not to mention the design and operation of aneroid devices, the relationship of atmospheric pressure with weather changes. Physics Grade 8 ...
1) Aneroid barometer is a device designed to measure atmospheric pressure. His heart - aneroid - a round, corrugated metal box from which air is pumped out, that is, discharged to tens of mm are achieved. Hg. Art. and less. Under the influence of atmospheric pressure, the box is compressed to an equilibrium state; the elastic force of the box itself and the transmission spring does not completely crush it. The box itself is made, as a rule, of beryllium bronze or similar alloys with high wear resistance and low KTLR (coefficient of expansion temperature) to minimize the error of readings when the temperature changes. The deformation of the box with a change in atmospheric pressure is insignificant, therefore, a transmission mechanism is installed in the barometer, which allows you to increase the magnitude of these deformations and use the arrow to translate it into atmospheric pressure.
With increasing blood pressure on the box, the effect increases, it shrinks harder and the arrow tells us how much pressure has increased, when it decreases, it decompresses under the action of the elastic forces of the box and the transmission spring, and again we determine the magnitude of the change on a scale. Tapping on the device is necessary to eliminate the effect on the indications of friction in the gear mechanism - it is a system of levers on the axles, and friction forces arise in them. But, as a rule, with a properly functioning device, this manipulation does not cause changes in readings by more than 1-2 mm. Hg. Art. The measurement range for blood pressure by household barometers is small, from 700 to 800 mm. Hg. Art. and less. When flying by air, the cabin pressure reaches 600 mm. Hg. Art. and below, during transportation of such a barometer, its breakdown may occur. As a rule, a delicate gear mechanism is damaged. The aneroid box can also become excessively deformed, which will affect the accuracy of readings in the future. The same can happen with a barometer and when exposed to pressures above 800 mm. Hg. Art.
2) The relationship between weather changes and changes in blood pressure was established by E. Torricelli, the creator of the mercury barometer. With a decrease in pressure, the weather "deteriorated", with an increase, "improved". When forecasting the weather, it is more important not the pressure itself, but its changes! For this, there is a second arrow on the glass of the barometer, which we combine with an arrow that displays the level of blood pressure. With a change in pressure, we can judge the trend of events. And it doesn’t matter at all whether we live in Astrakhan or in Pyatigorsk. There is no need to literally correlate with the inscriptions on the barometer (clear-variable-storm, etc.) with the state of the weather. Again, IMPORTANT CHANGE OF HELL. Say there is a wonderful clear weather outside the window. HELL \u003d 730 mm. Hg. Art. Then, after lunch, the arrow crawled down - expected to worsen the weather. The degree of deterioration depends on the magnitude of the change in blood pressure. And vice versa.
I hope my post will be useful to someone when choosing a borometer and its use.
Eugene 08/27/2013 09:08
Comrades, help me, pliz!
I found a completely disassembled barometer at home, an arrow separately, a mechanism separately, a metric scale (disk) separately. How to assemble this device to make it work?
Alexander 09/04/2013 15:38
Recently won 2 lots - a barometer (various, including a sea one, but in the style of "a la grandfather's barometer", which are full there, did not take, do not like) at the German eBay online auction. I had to look for happiness there, because modern clumsy antique fakes like RST or Utes and etc., which are now sold in Russia, do not inspire anyone to buy. And the price for them is ceiling and inadequate. This is so, by the way. These two barometers were sent to me from Belarus from Frankfurt to Main, like an ordinary air parcel by plane. The flight was postponed normally. Both workers. : ups: So, for some reason, air shipments for some reason did not have an effect on German barometers, although at first, in truth, there were concerns. On eBay, many barometers are sold around the world and the transfer of purchases (won lots) also goes to different parts of the world and usually it is air, and I have not met such issues. Maybe this applies only to Soviet barometers? Or is it a myth?
By the way, about setting up the barometer. The barometer readings are affected by your location above sea level, i.e., every 10.5 meters in altitude gives a pressure drop of 1 mm. Hg. Art (in English this is indicated by torr). Therefore, in order to fine-tune your barometer (which is already working well, that is, sensitive and does not have to be forced to push it with a tap), we take our feet in our hands and a thin screwdriver under your adjustment screw on the back of your barometer and direct our feet to the local weather station. There, we ask permission and goodwill and display on your barometer, which you brought with you, the same evidence as on the model from the weather station. We make a temperature correction if it is provided for in the barometer of the weather station (i.e., if there is no thermocompensated barometer there, and you have tambored there, for example, your marine barometer of the Japanese company YANAGI TYPE 8 COMPENSATED TEMPERATURE & ACCELERATION, which you won on eBay and cost you about Considering transportation from the United States at $ 200 and local meteorologists, the toad will begin to strangle).
After that, you have a barometer that is identical in indications to an exemplary weather station.
Alex 10/02/2013 15:22
P.S. And after they brought the barometer home and called back at the weather station and found a difference in the readings with them, it means that you and the weather station are at different heights relative to sea level. This is, as said above, a correlation (constant correction) to your location due to the difference in elevations.
Irina 09/13/2013 01:41
The Cliff barometer BTK SN8 large has been showing 750 mm unchanged for 2 days now. it's been raining all these days. I just got it, I haven’t seen any other indicators ...
Alexander 09/18/2013 10:52
P.S. With thermal compensation and the influence of your location (altitude relative to sea level), it seemed like he could chew popularly.
Now about the "development-running-in" of the barometer. To avoid problems during the operation of the barometer, I propose a very simple way to check it right at the place of purchase and bring it into working condition (reincarnation or “revitalization”) and increase sensitivity (reduce the impact of tapping). The operation is somewhat akin to checking at the site of a thermos - pouring hot water into it, wait a few minutes and check the temperature of the case. If it is slightly warm only in the area of \u200b\u200bthe cork, then it is whole and there is a vacuum. Distracted.
So, we take a strong transparent plastic bag (it’s better to reserve a few if they burst) in size larger than the barometer itself. We place the barometer in the bag, lay it on a flat, stable surface such as a table, inflate the bag with your mouth (like a ball), tightly close the exit of the bag. We make sure that there are no air leaks from the package. Click on the package. The barometer needle deviates upward, up to about 20 mmHg. (more efforts are not worth it). If the arrow deviates and returns back to the same position when removing the force on the package, then your barometer is operational.
We perform the same operation, only repeated, to “bring to life” your “falling into a coma, or maybe not leaving it” barometer. True, this can only help if the vacuum box in it is tight (there is a vacuum) and there are no other mechanical damage along the chain of the vacuum box - arrow.
And do not wait for six months or a year and knock on it, otherwise during this period turn into woodpecker. To do this, you need only some time to make some efforts to compress the inflated package. Physical exercises in moderation will not hurt anyone, the main thing is not to overdo it.
By the way, recently acquired the Soviet marine barometer of 1957 manufactured in accordance with GOST 6466-53 (now this GOST does not work). Awesome thing. On eBay, barometers of this type are usually sold in a round case under the brand name “Stalin era” or “period Cold War”. Many modern Shirpotrebsky clumsy single-chamber barometers are not suitable for him and soles. Triple vacuum chamber (to increase the force), a scale graduated through 0.5 mmHg, black rectangular bakelite case. No stupid inscriptions like "Sushi, Storm, Fair, Rain, Pogodnik and etc." There is no reaction to knocking on it. It works great. Once transported by bus, the trip took place in a very hilly area. It was interesting to observe his independent work. As soon as the bus drove into the lowlands, the pressure increased. As the bus drove up the hill, the pressure right in front of my eyes dropped. Those. The rule worked - each increase of 10.5 meters in height gives a fall of 1 mmHg. (torr) and back.
Alexandra 06/28/2014 12:32
Thank you so much. Your information is very valuable. I bought a BARO barometer, now I know that it is “live”, the focus with the package was a success. : love:
Roman 03/18/2015 22:29
Experience with a working package. And how to check the arrow the other way?
Igor 03/20/2015 23:47
Inflate the bag and burst it.
Alexander 06/26/2015 09:48
In this case, on the contrary - you need to create a small vacuum in the package, if you can 😎
Although why is it, if he reacts to excessive pressure, then he is a worker
Sergey 11/14/2013 05:09
I understand that transportation by air is prohibited, but if the plane does not rise above 7 km, does this rule apply to it? I simply do not have another transportation option.
Vasily 01/25/2014 07:21
I live in the countryside and there are no weather stations nearby. How to set up a barometer in such cases?
Yup 01/25/2014 2:41 p.m.
According to the weather forecast from the Internet for your countryside.
Alex 01/30/2014 17:24
Try to get out of your countryside and drive to a local weather station. This is if the hilly area. If in any way, the terrain is flat and the difference in elevation should not influence the readings, in theory, it’s better to get through to the local weather station and check the readings with them. Usually weather stations are in all district centers.
victor 03/04/2014 18:20
My barometer packs 770 mm, and the Internet - 750. What should I do?
CAT 06/13/2014 20:35
Tell me, where is the pressure higher: on the ground floor or on the tenth?
Galina 07/04/2014 13:51
Help ... They presented meteorological angle of the BRIGANT company with a barometer, hygrometer, thermometer, clock. Set up the black arrow with the screw, focusing on the weather data. But the barometer readings have been the same for a week now. It's a shame. What to do?
Alexander 08/08/2014 06:39
Galina 2014-07-04 13:51:18
In such "devices", one does not have to rely on any accuracy and repeatability of measurement.
The friction force in the transmission mechanism is such that the needle may not budge even when the pressure changes within + - 10 mm Hg.
If you need a device that measures atmospheric pressure, and not just a display device, then I recommend the following models: BAMM-1 (+ - 1.5 mm Hg). M-67 (Control - + - 0.8 mm Hg), M-110 and the like. The error is indicated, of course, for the entire measuring range of the device, that is, from 600 mmHg to 800 and, as a rule, in the measuring range 710-790, the correction is not introduced at all, only the temperature (for many devices that I checked, it is 0 )
One user wrote about flights from Germany and everything is OK - I do not agree with you. In order to declare this, it is necessary to check in the thermo-pressure chamber, in the entire working range.
Antoha 08/08/2014 18:28
Good day to all! I’ll tell you about my own. About 3 years ago I bought the BK-S barometer in 1978, the condition is excellent. He showed about 753, so sagged for two months, maybe it changed, but very slightly. Once a friend came and drew attention to him, they got into a conversation and I told the whole story, on which he suggested that I set up and check the device. I set it up and checked it in the metrology laboratory, drove it for about a week in some kind of pressure chamber, I don’t know for sure, in general, it brought me, said that the barometer is a thing, it showed clearly, it reacted very quickly. When I returned, showed 746, then I looked in neta - so itself + - 1-2 units. I hung and forgot, but when I look, the maximum units change by 10-12 at any time of the year. Even when it is raining, my arrow is “hanging” above 740 on a scale between “wind” and “variable”, although “rain” is 720-730 on it. I looked at the same Yandex weather, everything is that way, the pressure is 742. Therefore, I think it depends on the terrain and topography, or maybe something in nature has changed !!! I live in Stary Oskol, Belgorod Region.
Alexander 08/28/2014 06:17
As already mentioned here repeatedly, changes in weather and inscriptions on the barometer itself are in no way connected! The important thing is not the very value of atmospheric pressure, but the tendency to change it! In mountainous areas, normal pressure can never rise above 700 mm Hg at all, so do you think there are heavy rains and hurricanes?
Ilyas 04/17/2017 23:09
Tell me please. They presented a barometer in Rostov-on-Don (it worked as expected), after I brought it home by car to Pyatigorsk, it stopped working, hangs, and is silent. Transport in soft packaging - impact is excluded, in a horizontal position. How to reanimate and make it work?
NIKOLAI 01/29/2015 19:57
Dear friends! No need to configure anything.
At the factory, they (barometers) are set according to the standard. And since each area has its own height in relation to the sea, then the readings will be different.
This applies specifically to the factory.
As for others, I will not say anything.
But after your “setup” there will be “glitches”.
Example. In Moscow (center) 739 mm RT. Art., in Lyubertsy 750.
It's raining in Moscow, And in Lyubertsy there is neither a cloud, nor wind, in this example there is a big run, but it is.
Once we went fishing, the weather is calm, the morning is just “class”. Having traveled 15-17 km, the weather sharply worsened, having stayed for 2-3 hours in the pouring rain, returned with nothing, while returning back, the weather was the same - calm, not a cloud, the sun, quiet and grace. Interviewing about the weather, they were very surprised - nothing changed, and there on the horizon (looking from the roof of the house) a black streak of bad weather.
Draw conclusions. and you can climb the barometer mechanisms.
Thank you, success!
Olga 09/14/2015 15:40
I checked the barometer with a package, everything works. Thanks for the advice.
Zinaida 09/15/2015 13:19
Alexander, your comments are very useful, but I can’t set up my BARO hPa barometer, because the numbers on it are from 980 to 1040, and the pressure we have in the city of Novosibirsk is 740-760. Even if they say exactly at the weather station mm. Hg. Art., what next. And I still can’t understand how to set, or rather, which arrow the required numbers are. I have two arrows on it, black and golden, black moves up and down, and the golden one stands still. Tell me please. Acquired without instructions. Many thanks!
Roman 09/15/2017 10:34
1 hPa \u003d 0.750062 mm. Hg. Art.
hPa (in Russian hPa) - hecto-pascal - a unit of pressure measurement.
Accordingly, 750 mmHg equal to 999.9 hPa.
Alexander 10/19/2015 15:47
They presented St. Petersburg Brig, I can’t adjust it to the reduced pressure at sea level. There isn’t enough adjustment progress in + and the hand is scraping on the dial. The real pressure shows. We have 480 meters above the Baltic. The weather station from the same company is perfectly regulated. You don’t even have to click. I configured everything according to the airport, because I am at the height of their weather station.
How to disassemble and rearrange the arrow?
Nikita 12/03/2015 01:17
I bought a barometer, they said Russian, but there was no manufacturer in the instructions, and on the internet the weather station is exactly the same as the Chinese one I’m watching. The arrow deviates, does not freeze, i.e. it seems to work; the difference with the district center - plus one in it (district center) benefit (I check on an Internet). But the question is: the yellow arrow in my model does not move (the black one can be adjusted with a screwdriver, which is attached), the yellow froze by 748 mm. Hg. Art. ? This is normal? Cliff’s father’s house (with a yellow dial and a bunch of inscriptions) has been working well for a couple of years. He also watches only the deviation of the arrow when he goes to fish. But his yellow arrow rotates freely.
Threat. I read all the tips, thank you. There is a lot of useful information on how to use this device. Now, on the local advice, I look at the deviation of the black arrow up or down from the yellow one, and so I try to determine the weather.
Nikita 12/08/2015 20:22
By the way, if anyone has a BAMM-1 barometer, tell me how to set it up so as not to break it (I got it by chance, but I don’t know yet whether it’s working), and in which case should I set it up at all?
Gerhard Schroeder 11/25/2016 1:31 p.m.
I am doing it very simply: I am setting up casio according to the built-in barometer of the clock. If there is no watch, perhaps your phone can measure pressure.
Alexander 11/30/2016 19:48
About the flight. He traveled from Moscow to Vladivostok by plane. At an altitude of 10,000 km, it showed a complete discharge, i.e. the arrow lay in the leftmost position. As soon as the decline began and the arrow crawled, it was very interesting to observe, especially when it fell from 1 km to 500 meters. The arrow was ready to jump out. He brought it home, hung it on the wall, two days later he began to live his usual life and shows all the changes. therefore, flights are not afraid of him, it all depends on the quality. My is still old from the USSR, maybe that's why it still works.
Yuri 01/30/2017 07:52
I bought a barometer on Ali for 20 bucks. The diameter of the dial is 12.8 cm. Delivered by plane through Finland. It shows normally, but without tapping it does not want to. I’ve been watching for two days, now it showed 756 mm. Hg. Art., tapped, began to show 754.5, I think it will be developed over time. And also there is a thermometer and a hygrometer on it.
Natalya 09/15/2017 05:49
The old German barometer was transporting by plane in luggage, she was afraid that the antiques would not be allowed abroad. There was no other transportation option other than an airplane. As a result, the barometer does not work. I live in Latvia. What can be done, where and how to repair? Maybe it is possible to replace the damaged part?
Vlad 09/15/2017 10:27
Natalya, why did you decide that it does not work? Does the arrow not move or is overflowed? Maybe in your area the pressure does not change markedly.
If it is truly broken, I think there is an option to show the watchmaker. If a gear jumped there, traction or a spring broke, the watchmaker will be able to fix the device. Good luck Report the result here.
Vladimir 10/08/2017 19:10
A very tight arrow, moves only from a strong tapping. Maybe disassemble and lubricate the mechanism? Soviet device, cliff. Will the grease damage the part? Which oil to use? Machine or silicone? Thank you for the answers who have had a similar experience.
From childhood, a modern person gains access to complex and functional electronic devices. Such accessibility of equipment has led to the fact that classic devices almost do not cause interest and gather dust on shelves in complete oblivion. All these compasses, thermometers and barometers, with the help of which our grandfathers and even our parents navigated the world and assessed the state of the environment, seem outdated and boring toys. And in vain. That's about the barometer and I would like to talk in more detail. Because, despite the obvious and rapid technological progress, this device remains an indispensable tool for determining atmospheric pressure. But it equally influenced and influences what on us, what on our ancestors. And even today, when everyone can have a portable weather station in their pocket, the principle of that same barometer is still the basis of its work.
Of course, barometers now differ from their oldest prototypes - both externally, constructively, and functionally. But the essence of their action remained the same, and it is indispensable for every person who does not live in conditions of complete isolation from the world around and breathing air. Atmospheric pressure affects everyone and everything. And, if we usually notice the weather and its phenomena, such as the sun, rain, wind, then it is worth considering that all these manifestations can be predicted in advance by measuring atmospheric pressure with a barometer. Such measurements help to prepare in advance for the upcoming drops of weather dependent people and those who just go on a long trip and want to know what weather will accompany him on the way. To do this, you can just watch the forecast on TV or on the Internet, but it is much more reliable to control what is happening yourself. And for this, it does not hurt to learn how to use a barometer.
The structure and functions of the barometer
A barometer is a device that measures atmospheric pressure and shows the results of these measurements in human-readable quantities. But he does not have artificial intelligence and has no direct connection with space satellites. So how does he do it? Yes, very simple. The basis of the action of the simplest barometer was the ability of a fluid to move under air pressure. The first liquid used for this purpose was mercury, enclosed in a thin vertically oriented glass tube. The author of this design, Evangelista Torricelli, thought back in 1643 to lower a hollow tube sealed from the upper end into a vessel with mercury and observe how, under pressure, the "mercury column" rises or falls.
Rumor has it that Galileo himself inspired him for the genius of the time. But be that as it may, the mercury barometer was a rather dangerous device, and therefore, almost from the moment of its creation, the search for other options that did not involve the use of toxic liquids began. It was possible to find a satisfactory method only by the middle of the 19th century, when compatriot Torricelli Lucien Vidi revealed to the world the mercury-free and generally liquid-free barometer he invented, which he naturally dubbed aneroid (in Latin - “without liquid”). The aneroid barometer immediately appealed to the sailors, because it withstood ship rolling and shaking, and they use similar devices to this day. In fact, they also have nothing complicated: just a metal box with thin walls, inside which is a vacuum or very thin air. The air pressure bends the metal, and he, in turn, pulls the attached spring. An arrow is attached to the spring, indicating scale divisions.
The main advantage of this design is safety and accessibility. The main disadvantage is the small accuracy compared to the mercury column. Therefore, funny as it may seem, the readings of aneroids are sometimes rechecked using liquid barometers. For travelers and fans of yachting, the accuracy of the readings is very important. Oddly enough, many of them still use classic aneroids - either there is a certain charm in this, or conservatism affects. Although today the problem of measurement error has practically disappeared, and traditional models of barometers play the role of status souvenirs and stylish decor rather than measuring instruments.
If you need to know the atmospheric pressure, it is much easier to use a compact electronic barometer. In it, metal plates have been successfully replaced by microscopic capacitors and circuits, sometimes by crystals. Such a digital device can easily be integrated into a watch and / or a radio receiver, does not take up much space and does not fail in the data provided. Moreover, recently there have even been barometers built into mobile phones, and special applications for smartphones, not only measuring pressure, but also related to GPS-navigators. In other words, there is nothing easier than to find out the current and future state of the atmosphere, the weather for tomorrow at different points on the globe. But, if not for the first barometers invented almost half a millennium ago, one could only dream of this new-fangled comfort.
Rules for using the barometer
So, there are several types of instruments for measuring atmospheric pressure, each of which is, in fact, a barometer, and at the same time has its own characteristics, advantages and disadvantages. But, if you still decide not to be limited to ultra-modern devices and master the use of the classic barometer, then there are good reasons. In some cases, this may be a desire to understand the structure of traditional technology, the desire for a classic style in the interior and everyday life, or simply curiosity. It happens that a desktop barometer is presented as an expensive souvenir, and it’s a pity not to use a new beautiful thing. In any case, the following tips for using the barometer at home will come in handy:
- Mercury barometer will show atmospheric pressure in millimeters on the mercury column. Mercury (possibly a different, safer, colored liquid) is located inside the dividing flask. The size of each division depends on the size of each specific barometer, specify it to avoid errors. Then just look at how high the bar rose inside the bulb and what number it indicates. Please note that the barometer must be strictly at the level of your eyes, otherwise the readings will be distorted. Try not to move the device and do not touch it at all, because its sensitivity is very high and data may be lost.
A mercury barometer is the simplest device, and it only shows the state of the atmosphere directly around itself, in the room where it is located. Therefore, to evaluate using it the pressure outside the window or even in the next room can be problematic. To do this, you will have to move the barometer to a new place and wait until it adapts to new conditions. Nevertheless, such a barometer has long been the most common device for measuring pressure, and it is no harder to master than learning to use a household thermometer. Today, most residential buildings and offices use more modern and functional barometers, but if necessary, the mercury model can still be found and bought in a pharmacy or household goods store.
- Aneroid box. It can be located on the table, be suspended from the wall in the bedroom (this can still be found in the homes of older people, whose well-being depends on atmospheric changes) or attached to the window glass. The size of this device can be different, from a very tiny kruglyash to an impressive “washer” in diameter. But outwardly, it always represents a dial with a movable arrow above it. On the dial, in addition to numerical designations, words can be written, such as: “Clear”, “Dry”, “Variable”, “Rain”, “Storm”, etc. As you might guess, these tips are for an even easier use of the barometer.
By and large, you only need to look at what word the arrow of the barometer indicates at the moment. All the technical subtleties will remain beyond your attention and should not worry you, because the necessary information in a simple and understandable form is already before your eyes. For your part, you can participate in making a short-term forecast and observing changes in the atmosphere, if the design of your barometer assumes the presence of not one but two arrows. You can turn the additional arrow according to the same principle by which you set a mechanical alarm clock. If you compare it with the second arrow, then after a while you can notice whether there have been changes in relation to this position - that is, whether the pressure has changed, and, if so, in which direction.
- Electronic barometer even easier to use than classic aneroid. Most often it is called a weather station for the possibility of combining several functions at once and for sufficiently detailed tracking of weather changes and forecasts. The only difficulty that you may encounter when reading readings is the confusion among the many numbers and icons displayed on the digital barometer. Indeed, in the pursuit of external spectacularity and design refinements, many electronics manufacturers forget that any device should be primarily convenient in practice. This is the main task of the ergonomics of the body and screen of the barometer, and not at all in its futuristic and amazing design.
An electronic barometer usually has a housing and a flexible sensor designed to be placed outside the window. Sensitively, the end of the sensor captures any changes in humidity, pressure, strength and direction of the wind on the street, and the screen on the body immediately (or with a minimum time delay) shows you information about this. Even in the simplest digital models of barometers, you can see the current time, air temperature (outdoors and / or indoors), air humidity and, of course, atmospheric pressure. The latter is traditionally transmitted in conventional "millimeters of mercury." And although there is no mercury column inside the barometer, but these units are considered generally accepted when it comes to measuring pressure. Most likely, your electronic barometer is not limited to digital indicators and at the same time diversifies the data with icon pictures depicting the sun, clouds or rain.
And finally, it remains to decide what type of barometer to choose for personal use. There can be no strict recommendations here, and you are free to focus on your own taste, fashion trends, interior style, or simply prevailing circumstances. The main thing is that it is convenient for you to use it, and information about atmospheric pressure and other weather parameters was clear, understandable and easy to read. After all, the primary function of the barometer is precisely this: to promptly and accurately inform you about the state of the environment. Focusing on it, you can plan your day in advance, which is especially important for representatives of mobile professions, enthusiastic hunters, fishers and tourists. For them, the barometer is simply indispensable, and therefore it will be a great gift for any holiday or just for no reason, as a sign of respect for their activities.
often require customization. This must be done so that the error of the device does not interfere with correctly predicting future weather. If the barometer is strongly confused, then the movements of its arrows will incorrectly display a drop or increase in pressure.Many customize and calibrate barometers themselves. The online store offers to buy mechanical aneroids, which are easy to learn and correct yourself if necessary. In order to properly configure home barometersFollow our tips below.
How to understand what a barometer needs to be configured?
Check your instrument readings. Track: compare its data with those broadcast on radio, television, or with a summary of the meteorological center. For comparison, take the information that is given specifically for your region. It is impossible to verify the readings of a home barometer with data for a neighboring region: at a distance of several kilometers these figures can vary significantly.
Normal error can be up to 8 mm. Hg. Art. If your barometer does not exceed the allowable error value, then you do not need to configure it. If the device displays the data with exactly this or a greater error, then it must be calibrated. It’s easy to do, after reading this article it will become absolutely clear how to properly configure barometers. Online store presents mechanical models that are easy to understand, you just have to follow our step-by-step tips.
How to set up a barometer?
· Find the thin black arrow. It is called a pointer and we need it in order to correctly set the sea level at which the device is located.
· There is a large adjustment screw on the back of the barometer. Take a regular size wrench and use it to turn the adjusting screw so that the black pointer shows the sea level that is true for your city.
· Recheck the correct position of the arrow.
· Check your atmospheric pressure for your location. Use the news bulletin or weather forecast.
· Using the center handle of the barometer, turn the second arrow so that it accurately indicates this data.
· Hang the barometer on the wall or place it on the table. Make sure that it works correctly: tilt the entire instrument body about 45 degrees. If the thin black index arrow turns clockwise, then everything is in order with your barometer: this is a normal reaction of the device to a change in position. But if the arrow does not make a turn, consult a specialist. The appliance may be in trouble or malfunction.
When checking your home barometer, do not forget that you need to check with accurate reports. In addition, it is desirable that the device is at the same height above sea level at which you - otherwise the weather forecast made on such a device will not make any sense. Also pay attention to the correct installation or installation of the barometer: only the correct location of the device will make its readings accurate. But, on the other hand, remember: there is no difference whether the device will stand in an apartment or house, or be on the street. When installed correctly, the barometer will show changes in atmospheric pressure correctly.
Most barometers do not require frequent calibration or adjustment. It is a durable device that is designed for many years of operation. Before taking any action, check carefully whether there really is an error in his testimony.
