vinfage ussr aspiration psychrometer M-34 Thermometer Hygrometer 1979 with case

Description

M-34 psychrometer aspiration (electric) with case.
Psychrometer aspiration M-34M is designed to measure the temperature of the air, and the temperature of the "wetted" thermometer to further calculate the parameters of air humidity. The measured values of the air temperature and the temperature of the "wetted" thermometer allow us to calculate the relative humidity in the range from 10 to 100 % at temperatures from -10 to 50°C.
The work of the psychrometer M-34M is based on the dependence of the temperature difference between dry and "wetted" thermometer and calculate the parameters of air humidity on special psychrometric tables or graphics. The air temperature is determined by the dry thermometer readings.
Technical characteristics of the psychrometer M-34M
Characteristics of m-34M Value
Air temperature measurement range
-25°C to 50°C
Measuring range "wet" thermometer
-10°C to 50°C
Measuring range of relative humidity at temperatures from 5°C to 40°C from 10 to 100%
Error depending on temperature
from ±2 - 6%
Limit of the random components of the errors of the thermometers, following the introduction of amendments to ±0.1°C
The air flow rate (aspiration) during the fan operation must be at least 2.0 m/sec at any moment.
Overall dimensions of the psychrometer M-34M, mm
Ø105 x 400
Weight, not more than, 1,3 kg
Supply voltage 220V from the AC power source at a frequency of (50±1) Hz
Power consumption M-34 M, no more than 30 VA
The principle of operation and device psychrometer M-34-M
The work of the psychrometer M-34M is based on the degree of cooling by evaporation of the tank "moistened" thermometer with the balance of heat exchange and depending on the amount of moisture in the ventilated air flow at a constant speed.
The temperature of the" wetted " thermometer and the temperature of the air, determine the relative humidity.
Psychrometer M-34-m consists of two main parts - 1 head and 3 thermal holder (see Fig. following.)
Inside the head there is an aspiration device consisting of a winding mechanism, an electric motor with a fan connected to an AC voltage of 220 V.
Thermometers 4 are installed on the thermal holder 3, one of which is "wetted", and the other is used to measure the temperature of the air.
Thermometers are protected from exposure to solar radiation as side-slats 5, and bottom-tubes 6.
At the bottom of the thermal holder is a device for regulating the speed of aspiration. It consists of a cone-shaped valve 8 and a spring-loaded screw 7. When the screw is rotated, a certain part of the section of the tube 9 is blocked, which leads to a change in the aspiration speed. Speed control to the specified value is carried out at the factory and, if necessary, at the verification Bureau.
When the fan rotates, air is sucked into the device, which flows around the tanks of thermometers, passes through the tube 9 to the fan and is thrown out through the slots in the aspiration head.
Attached to the psychrometer: a pipette for wetting, consisting of a glass tube inserted into a rubber balloon with a clip, a shield (windproof) to protect the aspirator from the influence of the wind, a metal hook for hanging the device for a ball on the aspiration head, calibration certificates to thermometers and passport.
To calculate the moisture content on the thermometer using psychrometric tables or calculated by the formula.
Before work to remove the outer screen to the right of the thermometer and wrap Baptiste in a single layer, covering the reservoir of the thermometer at a distance of 3 cm the pre-washed hands washed with clean water reservoir of the thermometer; moisten with distilled water the lawn, wrapped around the thermometer Baptiste tied with strings above and below the reservoir, cut the free end at 2-3 mm below the reservoir.
For wetting Batista should be used only distilled water.
In the production of observations psychrometer M-34-m set in the place where the humidity is determined, usually on a special column on the windward side, so that the air goes from the device to the post, and the observer at the count should be in such a position, so as not to affect the readings (on the leeward side).
The order of the psychrometer M-34M
1) when determining the humidity in the open air to remove the psychrometer from the room in the winter for 30 min., and in the summer for 15 min. before the reference and hang it in the prescribed place at a height of 2 m from the ground;
2) moisten the muslin on the reservoir of the thermometer, this wetting make for 4 min. before the start of the observations. To do this, take a rubber cylinder with a clip - pre-filled with distilled water, and a light push bring the water in the pipette is not closer than 1 cm to the edge, and keep at this level with the clip. Then insert the pipette into the inner protection tube and wet the Batiste. After waiting some time, without removing the pipette from the tube, release the clamp, absorbing the water in the container and remove the pipette;
3) turn on the electric motor of the psychrometer M-34-m, preferably to a stabilized AC power supply;
4) four minutes after starting the fan or turning on the electric motor, count on the thermometers. The countdown is removed with an accuracy of 0.25 scale division price, the temperature values are rounded to 0.1°C and the readings are corrected, taken on the passport thermometers. In thermometers, each scale division corresponds to 0.2°C. Odd tenths of degrees are determined by eye.
At an air temperature below 0 ° C, the psychrometer is carried out from the room half an hour before observations, immediately moisten the tank covered with Batista and turn on the aspiration device for 8 minutes. 3-4 minutes before the countdown, the aspiration device is switched on again, but do not re-wetting. Before counting, the observer should determine if the indication remains "wet" thermometer constant or changing. In the first case, the observer produces and records counts as usual. In the second-repeats all process of supervision at first.
Before to produce samples, you should see frosting or soft Batiste tank thermometer to do this with a wooden stick (the size, approximately, from spitsino) apply to moistened Batista (create a center of crystallization). The wand (can be other material) must have the ambient temperature, so as not to introduce additional heat to the water on Batista.
After this operation, the Batiste should be solid, then mark next to the record of the wetted thermometer readings: the letter "L" the presence of ice on the Batiste and the letter "B" the presence of water in it.
To protect the fan from the action of strong wind (over 4 m/s) on the slots of the aspiration head from the windward side, it is necessary to put on the windscreen with the open end in the direction of rotation of the fan.
Determination of relative humidity can be made by the formula:
f= Em - A * P * ( At) * 100%
EU
where f is the value of the relative humidity;
Em-saturated elasticity of water vapor at the temperature of the "wetted" thermometer;
EU - saturated vapor pressure at the temperature of dry thermometer;
A-psychrometric coefficient equal to 6,62010 " 4 (°C-1)
P-air pressure;
At-the difference between the air temperature t and the temperature of the "wetted" thermometer t.
In practice, the relative humidity is determined by means of psychrometric tables, which specify the rules for their use (see "Psychrometric tables" author DP Bespalov, etc.).
In addition, the determination of relative humidity on the readings of the psychrometer, but with less accuracy (without adjusting the pressure to the elasticity of water vapor for the most common range of humidity - from 10 to 100% at a temperature of 5 to 40 °C can be made on the psychrometric chart.
Determination of relative humidity on the psychrometric chart is made in the following order:
the vertical lines mark the readings of the dry thermometer;
- for directional indications "wet" thermometer;
- at the intersection of these lines, the relative humidity values expressed as a percentage are obtained. The lines corresponding to tens of percent are indicated on the chart in figures: 10, 20, 30, 40, 50, 60, 70, 80, 90.
Example: the temperature of the " dry " thermometer 21,7°C, the temperature of the "wetted" thermometer 14,3°C. on the chart we find the intersection of the vertical and inclined lines corresponding to these temperatures; it is above 42, but below 44. Hence, the relative humidity will be approximately 43%.
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