SU1339405A1 - Piezometric level gauge - Google Patents

Abstract

This invention relates to a device for automatically controlling the level of liquid media. The purpose of the invention is to improve the measurement accuracy. As the level increases to the upper limit of the measurement site, the output signal of the differential pressure gauge becomes maximum. (/ С С 4 СП

Description

the comparison element 6 is activated, the pulsator 10 emits a pulse P, the pressure, the valve 17 closes, the pneumatic relay 14 opens and the valve 18. The input of the comparison element 19 comes from the setpoint 20 pressure s, and the input of the repeater 21 goes through the opener from the comparison element 19, the signal P, equal to the sum of the compensation pressure P generated by the repeater 21 and the pressure P

go

coming from master

20. At the output of the repeater 21, a compensation signal is formed more

one

The invention relates to instrument engineering and can be used in industry sectors where it is necessary to automatically control the level of liquid media, for example, in the chemical industry. The aim of the invention is to improve the measurement accuracy by introducing one common setpoint compensation pressure generator. all measurement sites.

FIG. 1 shows a diagram of a piezometric level gauge in FIG. 2, a graph of its operation.

The level gauge contains a piezometric tube 1 connected to the air supply unit 2 and the positive chamber of the differential pressure gauge 3, a two-scale indicating device 4, one input of which is connected to the output of the differential pressure gauge 3, and a switch of 5 measurement sections, the output of which is connected to the minus chamber of the differential pressure gauge 3 and the second the input of the indicating device 4. The switch 5 of measurement sites contains elements 6 and 7 of comparison, the first inputs of which are connected to the sensors 8 and 9 of the pressure of the upper and lower response levels, the second inputs - with the output d imanometr, and the outputs - with the inputs of pulsators 10 and 11 with regulating throttles 12 and 13, normally closed pneumoregles 14 and 15, the connecting inputs of which are connected to the outputs of the corresponding impres- sive value by the pressure value P equal to the measuring range of the differential pressure gauge. After the pressure pulse has been removed, the closed pneumorel 14 connects the first inlet of the comparison element 19 to the atmosphere. The device moves to one section above the previous measurement section, inside which the output signal of the differential pressure gauge also varies from the minimum to the maximum value. When the level drops to the lower limit of the measurement site, the value of P decreases by. 2 Il.

pulsators 10 and 11 and the inputs of the R1PI element 16, the output of which is connected to the control inputs of the normally open valve 17 and normally closed (valve 18, the first and second inputs of the comparison element 19 are connected through the corresponding normally closed pneumorele 14 and; 15 to the output of the setting unit 20 of the compensation pressure, the outlet of the comparison element 19 is connected via a normally closed valve 18 to the input of the repeater 21, and the third input of the comparison element 19 is connected via a normally open valve 17 to the output of the 2T repeater, which is the first stroke of eklyuchatel.

Level gauge works as follows.

In the first section, the comhHaj ioHHoe pressure, which is postggae to the minus chamber of the differential pressure gauge 3 from the output of the measurement section switch, is zero, the differential pressure meter measures the proportional pressure,

 coming from piezometric

tube, and its output signal is fed to the first input of the two-channel indicating device 4 and is read from the first scale. Upon reaching

0

the magnitude of the upper limit of the measurement site, the output signal of the differential pressure gauge reaches a maximum, the reference element 6 is triggered, and the pulse 10 or gives a pressure pulse P (j, the duration of which is determined by

313

This is done by adjusting the throttles 12. This closes the valve 17, opens the pneumatic switch 14 and valve 18, at the first input of the comparison element 19 through the opened pneumatic switch 14 comes from the setpoint 20 pressure P equal to the pressure of the measuring section, and the normally closed pneumatic relay 15 connects the second input element 19 compared with the atmosphere, i.e. the pressure supplied to the second input of the reference element 19 is zero, to the input of the repeater 21 through the opened valve 18 comes from the comparison element 19 pressure P ;, equal to the pressure P (figure 2) and the differential pressure gauge measurement range, and at the output of the repeater 21 The compensation pressure Rc P is formed, which enters the negative chamber of the differential pressure gauge 3 and the second input of the indicating device 4 (Fig. 2). After the pulse P, d is removed, the valve 18 and the pneumorel valve l4 close, the valve 17 opens on the repeater 21 and in the negative chamber of the differential pressure gauge 3 a pressure P is stored, which enters the input of the comparison element 19 through the opened valve 17. The closed pneumatic sea 14 connects the first input of the element 19 of comparison with the atmosphere, i.e. the pressure supplied to the first input of the element 19 of the comparison, is zero. In this case, at the output of the comparison element 19, a signal P, P is formed (Fig. 2), the device moves to the second measurement section, inside which the output signal of the differential pressure gauge also changes from minimum to maximum, and the level value is defined as the sum of the readings of the first scale the secondary device and its second scale, calibrated in units of multiples of the measuring range of the differential pressure gauge. With a further increase in the level to the upper limit of the measurement site, the output signal of the differential pressure gauge becomes maximum, the comparison element 6 triggers, the pulsator 10 outputs P, the valve 17 closes, the pneumatic relay 14 opens and the valve 18, the first input element 19 of the comparison comes from the setpoint 20 pressure P , to the input of the repeater 21 through the opened valve 18 comes from the comparison element 19 the signal P „PK + and at the output repeat-pa

4054

21, the switch 5 forms a compensating signal greater than the previous value by an amount P, d equal to the measurement range of the differential pressure gauge, the readings of the second scale of the indicating device 4 change accordingly (Fig. 2). After the pulse is removed, the valve 18 and the pneumoregle close

1Q 14, on the repeater 21 and, therefore, in the minus chamber of the differential pressure gauge 3, the pressure P + P is stored which enters the input of the comparison element 19 through the open valve

15 17. A closed pneumorella 14 connects the first inlet of the comparison element 19 to the atmosphere, i.e. the pressure applied to the first inlet of element 19. the comparison is zero. At the same time

20, the output of the comparison element 19 forms the P + signal (Fig. 2), and the device moves one site above the previous measurement section, inside which the output signal

25 of the differential pressure gauge also varies from the minimum to the maximum value. With a further increase in the level of the measurement area, the response cycle of the elements is repeated, and 30 the value of the compensation pressure increases by an additional value P,

When the level drops to the lower limit of the measurement section, the output signal of the differential pressure gauge becomes minimum, the comparison element 7 is triggered, the pulsator 11 increases P, the duration of which is determined by the setting of the throttles 13. This closes the valve 17, opens

40 pneumorel 15 and valve 18, to the second input of the comparison element 19, pressure P comes from unit 20 and is equal to the pressure value of the measurement section to the follower 21 input.

The opened valve 18 comes from the comparison element 19, the signal P, RK P and at the output of the repeater 21, the switch 5 generates a compensation signal less than the previous value of Pj equal to the measuring range of the differential pressure gauge, the second scale of the indicating device 4 changes accordingly (Fig .2). After removing the pulse P

gg, the valve 18 and the pneumatic discharge valve 15 are closed, on the repeater 21 and, consequently, in the negative chamber of the differential pressure gauge 3, the pressure Pc - Pj is memorized, (soto-1) is fed to the input of the element 19

51

through the opened valve 17. The closed pneumorelle 15 connects the second inlet of the element 19 to the comparison with the atmosphere, i.e. the pressure applied to the second inlet of the reference element 19 is zero. At the same time, at the output of the comparison element 19, the signal P Pj, - (Fig. 2) is formed, and the device goes one segment below the previous measurement section, inside which the output signal of the differential pressure gauge also varies from maximum to minimum. With a further decrease in the level of the measurement area, the cycle of operation of the elements repeats, and the value of the compensation pressure decreases even by the value of P ,,.

Claims (1)

Invention Formula A piezometric transducer containing a piezometric tube connected to the air supply unit and the plus chamber of the differential pressure gauge, a two-scale indicating instrument, one input of which is connected to the output of the differential pressure gauge and the other to the negative measurement chamber of the measurement section that includes two setters of the upper and lower levels , two valves, an OR element, a repeater, two pulsators, two comparison elements, the first inputs of which are respectively connected to the outputs of pressure units 10 15 394056 In addition, the second inputs are connected to the output of the differential pressure meter, and the outputs of the comparison elements are respectively connected to the inputs of the pulsators, the outputs of the pulsers are connected via the OR element to the control input of the normally open valve, the output of the normally closed valve is connected to the input of the repeater, the input is normal An open valve is connected to a repeater, which is the output of a switch of measurement sites, characterized in that, in order to improve the measurement accuracy, the switch In addition, a compensation pressure setter, two normally closed pneumoregles, a reference element were added to the measurements, the first negative and second accumulative inputs of the comparison element being connected through the first and second pneumorele to the output of the compensation pressure setting unit, the control inputs of the first and second pneumorele connected to the outputs of the first and second pulsers, the output of the reference element is connected to the inlet of the normally closed valve, the control input of the normally closed valve with union of a control input of a normally open valve, and the third element of positive comparator input connected to the output of a normally open valve. 20 thirty 35 VNIIPI Order 4211/31 Random polygons pr-tie, Uzhgorod, st. Project, 4 Circulation 93 Subscription