SU89279A1 - Photoelectric nephelometer - Google Patents

Description

The subject of the invention is a photoelectric nephelometer with two photocells included in the differential circuit.

The proposed photoelectric nephelometer differs from the known ones in that its measuring chamber is made in the form of a photometric ball, i.e. a ball, the inner surface of which has the property of diffuse reflection, which makes it possible to measure the integral light scattering of aerosols. The use of such a nephelometer eliminates the effect on the measurement results of the scattering indicatrix shape, which varies with the turbidity of the air.

Pa figs. 1 schematically shows the proposed photoelectric nephelometer; in fig. 2 is an electrical circuit for switching on the photocell of the nephelometer and driving its diaphragm; in fig. 3 is an electrical control circuit of a turbidity meter.

A photoelectric nephelometer consists of a ball 1, the inner surface of which has the property of diffuse reflection, a light source 2 (incandescent lamp), two fluorescent elements 3 and 4, an aspirator 5 for sucking aerosol, a reference aperture 6 and a crane 7.

Photovoltaic cells, one of which is mounted against the wall of the ball and the other in the tube at the bottom of the ball, are included as shown in FIG. 2

The first cascade of the amplifier is a magnetic amplifier 8 with windings Vi, Wi and Wz, W. It is a sensitive null element that can be used as an indicator of circuit detuning (Fig. 2) when using the circuit as a reference ( without registering). If registration is necessary, the amplifier acts on the servo drive motor 9, which balances the measuring circuit by moving the aperture 1J of the photocell 4 with the help of a gearbox 10.

Two windings Ws and Ws, located on the extreme rods of the amplifier, are connected in series and counter and are connected to the voltage No. 83279-2 for the output (clamps a and b) of the phase bridge 12, which is connected to the winding of the transformer 13. Wi, Wi windings and Wz, W / are connected in series and flow around the photocell current 3 and 4. The winding W of the middle rod is connected to the grid of the lamp M.

All like-windings are made with equal numbers of turns. If the windings Wi, Wi n Ws, Wa are de-energized or flow around equal currents, the voltage removed from the winding W is zero. If the current / s flowing through the windings Wi, W, is not equal to the current / 2 in the windings W-2. , then at the terminals of the winding W appears emf. double frequency compared to the emf, nitayndey winding W: j and a magnetic amplifier. In this case, the phase of the voltage on the winding W4 depends on the sign of the difference / 1- / 2 and changes by 180 ° when the sign changes.

E.D.S. the winding wi is amplified by an intermediate gain stage (lamp M) n supplied to the grids of the lamp / 5 double phasing of the cascade. The anodes of the lamp 15 are powered by the voltage removed from the secondary winding of the transformer J / 6.

In the absence of a temporary emf applied to the grid of the lamp / 5, the anode currents in it are approximately equal to each other. In terms of phase bridge 12, the circuit 12 is adjusted so that it is boosted with an emf. The unbalance in the grids of the lamp 75 always coincides in phase with the anodic voltage of one of the triodes and is out of phase in relation to the anodic voltage of the second triode. Thus, if the currents / i and / are not equal to each other, then a variable e appears on the grid.x of the lamp / 5. D. s., and the anode current of one of the triodes of the phased cascade increases sharply, and the other decreases sharply. The anode foils of the triodes may include a winding (frame) of a double-wound differential galvanometer, which will indicate the presence of an imbalance of the circuit. The balancing of the measuring circuit is made by changing the aperture opening //.

Instead of the impact of the photocell of the photocell by hand, the scheme can be turned into an automatic one.

In order to automatically influence the illumination of the photocell li, the anodic circuits of the phased cascade include windings of a three position relay polarized relay / 7, contact 18 of which controls the reversible DC motor 9. With a balanced circuit, pin 18 is in the middle position and the motor is stationary. When the imbalance of the engine starts to rotate, I will influence with the help of a diaphragm 11 on the illumination of the photocell. At the same time, the motor moves the pen 19, recording is made. 2-3 minutes before the measurement, the aspirator is turned on. The aerosol is sucked into the internal cavity of the shara.

Then the measurement circuit is turned on and the reading is made by comparing the illuminances of both photocells. Photo cells are selected, if possible, with identical characteristics.

With accurate measurements, it is advisable to preset the entire measurement scheme to zero, for which it is necessary to close the specks and turn on the aspirator for 5-10 minutes. A slight depression will appear in shchare and the nature of the scatter will approach the molecular one.

Subject invention

Claims (2)

1. A photoelectric nephelometer with two photocells included in the differential circuit, operating according to the comparison method, characterized in that, in order to measure the integral light scattering, the measuring chamber is made in the form of a photometric ball, the inner surface of which has the property of diffuse fencing. 2. In the photoelectric nephelometer according to claim 1, the use of an amplifying device with a magnetic amplifier in the first cascade, giving the output alternating current with a frequency twice as high as the frequency of the current, in a separate winding of the magnetic amplifier. uh s in.