SU339796A1 - DIFMANOMETER — GAS FLOW METER WITH AUTOMATIC ACCOUNT OF ITS PRESSURE AND TEMPERATURE - Google Patents

Description

This invention relates to a measurement technique.

In the known differential gas flowmeters with automatic consideration of its pressure and temperature, in which the correction input nodes are made in the form of two unbalanced electric bridges, the need to obtain the Lij conversion characteristics of these bridges in the required ranges of input values leads to a significant decrease in the level of Si1P1 in the line connection, which reduces the noise immunity and sensitivity of the circuit of a differential pressure gauge-flow meter.

In order to increase noise immunity and sensitivity in the proposed differential pressure flow meter, the input of the zero amplifier is connected to two parallel electric branches, one of which is formed by series-connected outputs of differential and pressure sensors, and the other branch is formed by series-connected output of a compensating converter and a resistance thermometer, and outputs of a differential sensor and compensating converter included in-phase.

The drawing shows the scheme described differential pressure gauge-flow meter containing a zero-amplifier I, the input of which is connected to two parallel electric branches m.

one CC of which contains connected in series outputs of differential pressure sensor 2 n pressure sensor 3, and the other branch contains compensating converter 4 connected in series and resistance thermometer 5, reversing motor 6 connected to zero-amplifier output 1 and kinematically connected to indicator 7 of the reading device and through a quadratic cam 8 with a plunger differential-transformer compensating converter 4.

Differential flow meter works as follows. Sensor 2 converts the pressure drop AP applied to it, which occurs on the restriction device when gas passes through it, into an alternating voltage proportional to the pressure drop.

UAP K & P AL

where / CA-P is the conversion coefficient of the differential sensor.

The output voltage of the UK differential transformer converter of the compensator 4 is related to the displacement and the pointer 7 by the relation:

/with . -coefficient of the pensator.

The parameters of the sensing element of the south element of the thermometer of resistance 5 are chosen in such a way that the absolute tempo is ensured in proportion to the resistance of the thermometer, the temperature of the environment

, / (j,. r,

where KI is the conversion coefficient of the thermocouple thermometer.

Similarly, the parameters of pressure sensor 3 are chosen so that both proportions of the resistance of the sensor to the absolute gas pressure applied to it are equal to each other.

  R,

where KP is the transform coefficient of the pressure sensor. With common-mode turn-on nanr / horse

Another value of the current J flowing in the circuit abed is expressed by the ratio

lr aj

g i T

or

/ Сдр-АР-1.Д; .

Cr-P + Cg-T

The current / flowing along the contour creates a drop in voltage of 7l on the wind sensor of sensor 3, which is received from voltage i / other. The difference of these two voltages is applied to the input of the null amplifier after rotation of the reversing motor 6. The motor 6 rotates: with such a direction that the kinematically associated with it through the quadratic cam 8 and the tuner of the compensator transformer 4 of the compensator 4 moves to then, until the circuit abed establishes the following 3: on | ch.ieniya current, three of which the difference in the direction of sensitivity of the device:

 Ur d (y,

: 0

threshold.

From the previously given relations it follows that at steady state

A - Upg dr - IRg AGDR.DDR + a2A: a

CRP 0

Mr. / SAY-ARK,

TO,

where

Have

/

/ SDR-DR-A: - t

Kn-K

KR-R-KO

/ Aa-tv x

i.e. the indications of the flow meter are in the same dependence on the pressure drop AL of the pressure P and the temperature T of the gas, in which the flow rate of the gas depends on these parameters

 c / subject of invention

Differential gas flow meter with an automatic one, taking into account its pressure and temperature, contains a differential transformer-type differential pressure sensor, a rheostat pressure sensor, a resistance thermometer, and an automatic compensating device with a differential transformer compensating converter and a zero-amplifier with a reversible sensor connected to it a motor kinematically coupled to a plunger of a compensating differential transformer converter, characterized in that, in order to raise an protection and sensitivity, in it the input of the null amplifier is connected to two parallel electric branches, one of which is formed by the outputs of the differential pressure sensors connected in series, and the other branch is formed by the compensating converter and the resistance thermometer connected in series, and the outputs of the differential sensor and the compensating converter are switched on in-phase.

che