SU800741A1 - Manometer - Google Patents

Description

(54) MANOMETER

one

The invention relates to measurement technology and can be widely used for measuring pressures from tenths up to a few atmospheres.

Fluid pressure gauges are known in which the measured pressure is balanced by the pressure created by the difference in the levels of the fluid in the communicating tubes 1. .

The disadvantage of such gauges is the difficulty of measuring significant movements, the warmth of such gauges, etc.

The closest in technical essence and the achieved effect to the proposed pressure gauge is a device that contains 1 tube with mercury and liquid, mercury level fixers with electrical circuit transform. nor is the controlled solenoid valve F21.

However, this device has the disadvantage that when measuring pressure on the order of P; 10 Pa, the difference in levels is about one meter and requires a large amount of mercury, which is an increased danger in an emergency situation, as well as measurement accuracy

The purpose of the invention is to improve the accuracy of conversion, increase reliability and reduce the size of the device.

This goal is achieved by the fact that the tube is equipped with capillary constrictions between which mercury is placed, the ends of the tube are connected to two outputs of a controlled electromagnetic valve, one of the inputs of which is connected to a source of measured pressure, the other - to a source of reference pressure, auxiliary winding valve - with the release of the circuit clamps levels.

FIG. 1 shows schematically the design and layout of the proposed pressure gauge / in FIG. 2 - time diagram of work.

The pressure gauge contains a glass tube 1 with a liquid and a capillary at the bottom 2, a column of mercury 3 is inserted into KOTOpiTO 3. Near the tube, photoprints are installed, capacitances 4 and 5 of mercury movement fixators. Photodetectors 4 and 5 are illuminated with light sources b (light fibers Al107), from which light streams are formed by narrow slits of the diaphragm 7. The ends of tube 1 are connected to two outlets, for example, a rotary switching solenoid valve 8. One valve inlet is connected to the environment, the other to a source measured pressure P. Thus, the solenoid valve connects to the capillary 2 or the sum of the measured P and the reference pressure PO / generated by the height of the mercury column (PO Nd), or their difference. These pressures applied to the capillary induce fluid flow, which is integrated by integrator 9 and converted to mercury displacement h. Upward mercury emissions are eliminated by capillary contraction 10 The displacement h is converted by photosensors 4 and 5 into electrical voltages and and, which are fed to the discriminator 11 levels Uf., And (} (aanpniviep Schmidt trigger). At the output of the discriminator, square impulses are generated, the duration of which is PIx and t, 2. is the output parameter. On the other hand, these pulses are sent to the driver 12 of the control of the electromagnetic valve. The pressure gauge operates as follows. In the initial state, the valve 8 is set to and a, in which the lower end of the tube is connected to the source of the measured pressure P, and the upper end to the environment. In the absence of the measured pressure (P 0), the mercury column 3 is in the lower extreme position and capillary Tapering 2 prevents mercury from moving down (pouring out) from Tube 1. If there is a measured pressure Ru, a higher pressure Pp created by the height of the mercury column and Ru Pp HQ, where t is the density of mercury, g is the acceleration of gravity, mercury starts to rise up. By neglecting, for simplicity, by the forces of resistance to uniform movement of mercury in a wide tube, it can be considered that the capillary 2 has a pressure rp under the action of which there is a constant fluid flow through the capillary 2 where R is the hydraulic resistance of the capillary liquid, is the length and the diameter of the capillary pa. The volume of the control unit S.-hfj, given by the area S and the distance hg between the photodetectors 4 and 5, is electrically fixed by the movement of mercury using a level-11 discriminator. The level-11 discriminator generates, at the output, rectangular voltage pulses whose duration t is equal to the time of uniform motion e.g. of an upper mercury meniscus between predetermined displacement levels h and h. Volume v (and at .osi, AV, i.). After some time delay created by shaper 12, solenoid valve 8 switches to position b, and the upper end of the tube is connected to the measured source, pressure Rd, and LOW The pressure P + PQ is now applied to the capillary 2. Under the action of which a constant reverse flow of fluid a is applied - Ell. The choke and distance hg the upper meniscus of mercury passes during the time t, determined from the flow equation I, - ja- - R a At different flow rates Q and fi one and the same volume is fixed. Equal The conversion (PX-RO) () -Ch and measured pressure does not depend on the dynamic resistance of the capillary, i.e., neither its geometric dimensions nor the viscosity of the liquid. The time diagram of the manometer operation is shown in Fig. 2. At the initial moment in @ м mvni t столб, the mercury column is in the lowest position under the action of a constant pressure R. R.-Rd applied to a capillary with dynamic resistance R | and a large dynamic capacity of the pressure source of low internal resistance. The integral flow characteristic is linear h, (t) Q. (right A, fig. 2). At the moments when h (t) is equal and the levels h and h of diacrnumdrem 11, positive pulses are fermented, the duration between which is equal to t. After the second discrimination pulse, the mercury column continues to move upward during the delay time At :, necessary for switching the valve and damping transients. After ds, the reverse movement of mercury begins and in the region, there is a steady process of uniform movement under the action of a constant pressure P + PQ on the capillary described by the linear integral characteristic of the flow rate h, (,. T (e) at the moments of an accident) and levels h negative pulses are formed that determine the duration of t. The output time parameter is the ratio of the sum to the difference in time intervals, t -. .- X -1 a and the result of the measurement of pressure Px -ce-v x does not depend not only on the dynamic resistance of the capillaries but also on the drift (s levels h and incomplete levels of the level discriminator. The small methodological error of the proposed pressure gauge allows transformations (error of tenths of a percent or less) caused by a stable support. The proposed pressure gauge, unlike conventional i-shaped gauges, allows, at a low height HQ of the mercury column, to measure high pressure PX / Ynr mm.ht. spill warning It is advisable to perform a capillary constriction of mercury from the tube 1 from above. To expand the capabilities of the pressure gauge, any liquid that does not react with mercury, such as distilled water, can be used as a working flow medium. integration, it is necessary to minimize changes in fluid levels in

- - .i constricting vessels by increasing the surface area of the liquid-air. The time parameter at the output of the proposed manometer makes it easy to obtain a measurement result in digital form. formula of the invention. A manometer containing a tube with mercury and a liquid, mercury level fixers with a conversion circuitry and a controlled solenoid valve, characterized in that, in order to increase the accuracy of pressure conversion, reduce size and increase reliability, the tube is provided with capillary contractions between which mercury, the ends of the tube are connected to two outputs of a controlled electromagnetic valve, one of the inputs of which is connected to a source of measured pressure, and the other to a source of reference pressure, and The control valve winding is connected to the output of the level lock circuit. Sources of information taken into account in the examination 1. UK patent number 1441266, cl. G 1 N., 2. Japan patent 50-2828, cl. 111 C 211, 1975 (prototype).

Claims (2)

Claim . A manometer containing a tube with mercury and a liquid, mercury level detectors with an electric conversion circuit and a controlled solenoid valve are distinguished by the fact that, in order to increase the accuracy of pressure conversion, reduce dimensions and increase reliability, the tube is equipped with capillary constrictions, between which contains mercury, the ends of the tube are connected to two outputs of a controlled solenoid valve, one of the inputs of which is connected to a source of measured pressure, and the other to a source of reference pressure , and the control winding of the valve is connected to the output of the circuit level detectors. 30 Sources of information taken into account in the examination 1. UK patent No. 1441266, CL G 1 N. 2. Japan patent 50-2828, 35 cells. Ill C 211, 1975 (prototype). Fig. /