RU1779946C - Method for checking turbine flowmeters - Google Patents

Abstract

Usage: verification of turbine gas and liquid flow meters. SUBSTANCE: turbines of a horizontally mounted counter are unwound to several fixed frequencies of rotation of a force action on it. The number of revolutions of the turbine is measured until it stops completely after the termination of each force. The same operations are performed on a counter installed at an angle to the horizontal, and the quality of the counter is judged by comparing the obtained dependences of the turbine run-off speed on the initial frequency of its rotation for different orientations of the counter in space with the analog dependencies obtained for the reference counter. 2 ill.

Description

The invention relates to measuring technique and can be used to verify turbine gas and liquid meters.

There is a known method for calibrating turbine meters, including supplying air to the meter being calibrated and controlling the speed of its turbine 1. The disadvantage of this method is that it uses gas measuring devices of the second category, in other words, complicated, expensive equipment.

There is also a known method for checking turbine meters, including spinning up a turbine of a horizontally installed meter to several fixed rotation frequencies by force acting on it, measuring the number of revolutions of the turbine until it stops completely after each power is stopped, and comparing the dependence of the speed of the turbine run-off on its initial frequency of rotation with the same relationship obtained for reference counter 2.

The disadvantage of this method is its low reliability, since the test conditions are inadequate for the workers (the influence of the axial force acting on the turbine bearings due to the high-speed pressure of the medium is not taken into account).

The purpose of the invention is to increase reliability.

The goal is achieved in that in a method for calibrating turbine meters, including spinning a turbine of a horizontally mounted meter to several fixed rotational speeds by force acting on it, measuring

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the number of revolutions of the turbine until it stops completely after the termination of each force action and comparing the dependence of the number of revolutions of the turbine on the initial frequency of its rotation with the same dependence obtained for the reference counter, additionally set the counter to an inclined position, finding the dependence of the number of revolutions of the turbine on the initial frequency of its rotation, and when comparing, the obtained dependence is compared with the same dependence obtained for a reference counter installed at the same angle to g horizons.

In FIG. 1 is a diagram of an apparatus for implementing the method; in FIG. 2 shows the dependence of the turbine run-out speed on the initial frequency of its rotation for the test and reference counters;

The device comprises a control unit 1, a rotary counter 4, a turbine speed sensor 3, a valve 4, a pipeline 5, a nozzle 6, a hinge 7. a start speed indicator 8 and a pulse counter 9.

The method is implemented as follows.

At the command of the control unit 1, compressed air is supplied into the internal cavity of a horizontally located verified meter 2 through valve 4 and nozzle 6 through line 5.

The counter turbine spins up to a predetermined number of revolutions, for example corresponding to a 100% flow rate. The speed control is carried out through the frequency sensor 3 by the indicator 8 of the starting speed of the control unit.

After the turbine reaches a predetermined number of revolutions (starting speed), the air supply is stopped and the counting of the number of revolutions of the impeller begins with a pulse counter 9 of the control unit until the rotation of the impeller stops.

The described operation is repeated for revolutions (starting frequency) corresponding to 80, 60. 40, 20% flow rate.

Then, the same operations are repeated with a counter inclined at 30-60 °, as shown in FIG. 1 dotted line. The nozzle 6 in this case also pivots on a hinge 7.

Testing the meter in an inclined position is necessary to take into account the axial friction in the support, which are created by the weight of the turbine. Under operating conditions, this friction occurs due to

the velocity head of the substance passing through the meter.

The results obtained from the meter tests are used to plot the graph shown in FIG. 2.

On the graph, the sector of restrictions is pre-plotted with dash-dotted lines 1 and 2. Line 1 corresponds to the minimum (close to 0) error of the test

size of a working counter in coordinates starting frequency FCT - sum of pulses Si. Line 2 corresponds to the data in the same coordinates for a working counter with a given maximum permissible error. Lines 3 and 4 are located inside sectors 1 and 2, corresponding to sectors with meter readings that have lower error values.

The test data of the counters at the starting frequencies is plotted, a curve is drawn, connecting the obtained points for the horizontal 6 and inclined 5 counter positions.

If both curves are for the same counter

located inside the sector 1-2, then its error does not exceed the permissible.

To more accurately determine the error, the position of the curves within the sector is considered. If the curves are located, for example, in the area of sector 1-3, then this counter has an actual error equal to 1/3 of the permissible.

Claims (1)

The claims A method for calibrating turbine meters, including spinning up a turbine of a horizontally installed meter to several fixed rotational speeds by force acting on it, measuring the number of revolutions of the turbine until it stops completely after each power is stopped and comparing the dependence of the run-out number of the turbine on the initial frequency of its rotation with the same dependence obtained for the reference counter, characterized in that, in order to increase reliability, set the counter in an inclined position, on running t dependence of the speed of run-out turbines from the initial frequency of its rotation, and when comparing, they compare the obtained dependence with the same dependence obtained for a reference counter installed at the same angle to the horizon. S /  Ј03 spirit.