SU447569A1 - Hydrostatic fluid level sensor - Google Patents

Description

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The invention relates to instrumentation and can be used in various industries.

Hydrostatic level sensors are known that contain an elastic sensing element immersed in a fluid associated with a power transducer.

However, in such a sensor, there is no operational control device, which would allow to check the operability of the sensor and the accuracy of its operation without dismantling directly in the process mode, which reduces the reliability of the sensor.

The proposed sensor for improving reliability is provided with an on-line monitoring device made in the form of two sealed chambers, one of which is connected to the internal cavity of the sensing element and to the pressure unit, and the other covers the sensitive element from the outside and is connected via n. about. valve with liquid in the tank, and through n. h - with a source of excess stabilized air pressure.

This increases the reliability of the device.

The drawing shows a schematic diagram of the sensor.

The sensor contains a sensing unit 1, installed on the side in the lower part of the tank with liquid, and a pneumatic force transducer 2. The transducer can also be electropower. The sensing element of the sensor is the bellows 3 (may be a membrane, etc.) with a rigid center 4 connected to the power stem 5. The inner chamber 6 in the bellows 3 is sealed, the cup membrane 7 supports the lever 8 pivotally connected to the power lever 5. Outside bellows 3 installed second sealed

chamber 9, in which there are two valves (valves) 10 and 11 with rods and bellows 12 and 13, springs 14 and 15, and housings 16 and 17. In the normal position, the upper valve is open, and fluid enters the chamber 9 through the open valve opening, and the bottom valve is closed, and the air under pressure P const does not flow into the chamber 9.

The pneumatic converter 2 consists of a weight lever 18 with a flap 19 connected through a support to the lever 8 of the sensing unit, an articulated support 20, a movable support 21, a nozzle 22, a repeater-amplifier 23, a feedback bellows 24 to the lever 25 and a spring zero equalizer . Besides, in

A sensor is provided with a overhead switch 27 for controlling valves 10 and 11, as well as a pressure setting device 28, the output of which is connected to the inner chamber of the bellows 3. The pressure of the setting device 28 is monitored by the pressure gauge 29, and

pressure P const - gauge 30.

The device works as follows.

At the bottom of the bellows 3, the hydrostatic pressure of the liquid column in the tank is applied, which is determined from the ratio P nN, where 7 is the specific gravity of the liquid, H is the height of the liquid column.

This pressure, multiplied by the effective area of the bottom of the bellows, through the levers 5 and 8 acts in the form of a force proportional to the pressure P jH, on the weight lever 18 of the pneumatic power converter. The valve 19 covers the nozzle 22, the pressure at the output of the repeater amplifier 23 and in the bellows 24 increases, and the lever 18 through the lever 25 and the support 21 is balanced in the new position. The pedestal 21 serves to adjust the range of variation of the output signal, the spring 26 to adjust the zero point.

The output signal of the sensor ROW when the liquid level changes is formed in proportion to the pressure P.

To control the operation of the sensor at any value of the liquid level I, the pneumotumbler 27 is turned on, valve 10 closes and valve 11 opens, and pressure P const is set in chamber 9, which must be higher than the maximum possible pressure in this chamber P oN when the sensor is working.

The unit 28 in the inner chamber 6 of the bellows 3 is set to pressure Px,

This pressure is changed in such a way that

that Pconsi - Px, RO UNO or Pconst -

- PX, - to simulate the lower level

fluids and Pconst - YAMAX PX, - FOR IMITATION of the upper level of the liquid.

To simulate all intermediate values of the level, the gauge 28 establishes the pressure PX "Pconst - m".

With all the indicated pressure values PX, the output signal Pbyh is checked according to the calibration table of the sensor. If necessary, it can be adjusted and calibrated by changing the measuring range, re-calibration for a liquid with a different specific weight.

After the test is completed, the unit 28 sets the pressure PX O, the pneumo-tumbler 27 turns off, and the sensor thus enters normal operation regardless of the level of liquid in the tank.

Subject invention

A hydrostatic fluid level sensor containing an elastic sensing element,

immersed in a fluid associated with a power converter, characterized in that, in order to increase reliability, it is equipped with an operational control device made in the form of two sealed chambers,

one of which is connected to the internal cavity of the sensing element and to the pressure setting device, while the other one is covered by the sensitive element on the external side and is connected via a n. about. valve with liquid in the tank, and through n. h - with a source of stabilized air pressure.

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P I f

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