SU1173212A1 - Device for pressure cell calibration - Google Patents

Abstract

A DEVICE FOR CALIBRATION OF PRESSURE SENSORS, containing a source of compressed gas, connected by a pneumatic route through an inlet throttle to a pipe in which fittings are placed for connecting graduated and exemplary pressure sensors, characterized in that, in order to improve accuracy and / J, shorten the calibration time by reducing fluctuations gas inside the pipe, it is provided with a cylinder with perforated walls, an output throttle, and first and second detachable taps with electric actuators, while the cylinder with perforation The installed walls are installed inside the pipe coaxially with it, the output choke is located at the pipe end face coaxially with it, the input choke is connected to the output of the first shut-off valve, the output of which is connected to the source of compressed gas by a pneumatic route, the output choke is connected to the output of the second from (/ / a) tap valve, the outlet of which is connected to the atmosphere, and the inlet and outlet chokes are made adjustable. to to

Description

 one

The invention relates to the control of measuring equipment, in particular to the technique of calibration and metrological certification of pressure sensors.

The aim of the invention is to improve the accuracy and shorten the calibration time by ensuring the stability of the pressure and the possibility of accommodating a large number of pressure sensors.

FIG. 1 shows a calibration device, FIG. 2, a change in the pressure in the device over time.

The device consists of a source 1 of compressed gas, a flue 2, an adjustable inlet throttle 3, a pipe

4c placed on her fittings

5dla installation of calibrated 6 and precision 7 pressure sensors, output adjustable throttle 8, shut-off valve 9, installed

in the duct 2 at the inlet to the adjustable inlet choke 3, shut-off valve 10 installed at the outlet of the regulated outlet throttle 8 in the duct 11 of the cylinder 12 with perforated walls (mesh) with evenly spaced holes, the area of one hole is selected at least 100 times less than the area of the entrance throttle 3, and the total area of the cross-section of the holes is not less than 10 times the area of the entrance throttle 3. The ratio of the areas of the holes to the cross-sectional area of the entrance throttles 3 is selected based on experience. The cylinder 12 is located in the pipe 4 after the inlet regulated throttle 3 and at the inlet to the outlet adjustable throttle 8. To control the initial pressure, a control primary converter 13 is installed in the source 1 of compressed gas, and to collect measurement information from the primary converters 6, 7 and 13 and controlling the operation of the shut-off cranes 9 and 10, a device 14 is established for communication with the object ;, the information is transmitted to the computer, and further control of the shut-off cranes 9 and 10.

The device works as follows

Graduated 6 and precision 7 pressure sensors are connected to fittings 5. Pick up depending on tepe732172

of the dynamic error of the filling time (pos. 15 in Fig. 2) or the time of pressure change in the pipe from the minimum value of 5 WMH to a maximum of f. (POS. 16, FIG. 2) by varying the flow area of adjustable chokes 3 and 8 according to preliminary graduations. Pressure sensors 6, 7 and 13, and

10 also the shut-off valves 9 and 10 are connected via a matching device 14 to a computer (not shown) for recording the readings and controlling the shut-off valves 9 and 10,

15 Shut-off valves 9 and 10 are closed and the calibration program of pressure sensors in the computer is entered, and pressure is applied in source 1 of compressed gas. When the pressure reaches 10% by

20 primary converter. (pos. 16) required by the command received from the computer, record the readings of the pressure sensors 6 and 7, then open the shut-off valve 9 and

5, sensor readings are recorded in parallel, and in a sequential survey, sequentially. In parallel polling, simultaneously graded and precision measurements are recorded.

0 pressure sensors. In a sequential survey, the readings of precision 7 are recorded first, followed by 6 calibrated sensors at regular intervals, and the entire cycle t; (pos. 17) is repeated again. When the full amplitude A is reached, shut-off valve 9 is closed and the shut-off valve 10 is opened. Backward movement registers the readings of pressure sensors 6 and 7 in the same sequence as during a forward stroke (precision 7 - graduated 6 pressure sensors). I

At the outflow of gas with supersonic

5, intensive resonant oscillations with a complex frequency spectrum multiple to the geometric dimensions of the cylinder and the dependent

0 from the pressure drop across the throttle 3. The arising intense oscillations create powerful vortices that are crushed by the perforated wall of the cylinder 12 into smaller ones, due to which

5, the uneven pressure along the length of the pipe 4 is reduced.

Resonant oscillations in a closed volume arise because the gas jet, which flows out of throttles at supersonic speeds, emits noise that is close to white, so that the emitted oscillations always coincide with a frequency corresponding to the natural frequencies of a limited volume. The pressure value for calibrated sensors with sequential otphos, is determined by the dependence hf A) + amplitude for the th transducer, amplitude 18, measured by a precision sensor before recording the pressure values of the calibrated sensors, amplitude 19, recorded by a precision sensor after recording the values of the calibrated sensors , P - the number of sensors, i - index of the calibrated sensor. The calibration is repeated as necessary depending on the method, then the results are processed and presented in the form of polynomials or tables indicating the errors of deviation from the readings of the precision sensor and are used later in deciphering the readings of the sensors installed on the object under study.

Claims (1)

DEVICE FOR GRADING ¹ · PRESSURE SENSORS, containing a source of compressed gas connected by a pneumatic route through an inlet throttle to a pipe in which fittings for connecting graduated and standard pressure sensors are located, characterized in that, in order to increase accuracy and reduce calibration time by reducing fluctuations gas inside the pipe, it is equipped with a cylinder with perforated walls, an output throttle and first and second shut-off valves with electric drives, while the cylinder is perforated with the walls installed inside the pipe coaxially with it, the output choke is located at the end of the pipe coaxially with it, and the input choke is connected by the input to the output of the first shut-off valve, the output of which is connected by a pneumatic route to the source of compressed gas, the output choke is connected to the input by the g key the second shut-off valve, the output of which is connected to the atmosphere, and the input and output chokes are adjustable. Fie! ” 117321?