SU1364927A1 - Device for measuring pressure in pipeline - Google Patents

Abstract

The invention relates to the field of instrumentation. The purpose of the invention is increased reliability. When the device is installed on the pipeline, the latter is laid in fixing slots, parts 1 and 2 are clamped together, as a result of which the pipeline through the protective element deforms elastic 10 and sensitive 9 elements until it is covered by locking grooves. With increasing pressure in the pipe 7, its outer diameter increases. The deformation of the pipeline through the protective element is transferred to the sensitive element 9, compressing it in one direction and simultaneously stretching in the other. During deformation, the sensing element 9 generates an electric charge, the magnitude of which is proportional to the deformation of the outer diameter of the pipeline, and therefore the pressure inside it. 1 3.p. f-ly, 4 ill. $ (L

Description

ten

00

but

four

;about

1C

U2.i

one

The invention relates to instrumentation engineering and can be used to measure and control the pressure of liquids and gases in a pipeline.

The aim of the invention is to increase reliability.

FIG. 1 shows a front view device; in fig. 2 - the same, side view; in fig. 3 shows section A-A in FIG. 2; in fig. 4 - lower part of the body in isometric projection.

The device contains a body consisting of two parts 1 and 2 interconnected movably: at one end they are connected with axis 3 and can be rotated around it, and at the other end with a detachable clip 4. In each part of the body there are the same internal cavities 5, and also fixing grooves 6 for the test pipeline 7 are formed. In each internal cavity 5, there are three existing 8, sensitive 9 and 10 elastic elements. In this case, the protective element 8 contacts simultaneously with the pipeline 7 and with one surface of the sensitive element 9, is one of the electrodes of the latter. The other electrode is a thin metal plate 11, which is connected by a conductor 12 to an axis 3 electrically insulated from the pipeline. The elastic element 10 is fixedly connected to the base of the cavity 5.

Between sensing 9 and elastic 10 elements, an additional elastic element 13 and a rigid gasket 14 are installed, fixedly connected to each other, as well as with sensitive 9 and elastic 10 elements, respectively. The fixed connection of the layers to each other, as well as to the inner surface of the cavity, is carried out, for example, with an adhesive.

A rigid gasket 14 is made of metal, for example of brass, and electrically connected to the protective element 8, forming a shield for the sensitive element 9.

Parts 1 and 2 of the body can be made, for example, of caprolon by injection molding.

The protective element 8 can be made for example of copper foil with a thickness of 0.05 mm.

,

R 0

five

0

five

0

five

72

A piezoelectric film, such as PVDF-1, can be used as the sensing element 9.

The elastic element 10 may be made of oil-resistant rubber, for example brand MBS-3826, 4 mm thick.

The intermediate elastic element 13 may be made for example of polyurethane with a thickness of 0.5 mm.

Tight gasket 14 can be made for example of brass with a thickness of 0.3 mm.

The operation of the device is as follows.

Before installing the device in the pipeline, the clamp 4 is open, parts I and 2 are separated to the side by turning them around axis 3, and the elastic elements 10 and 13 and the sensitive element 9 are in a free undeformed state. In this case, the outer surface of the protective element 8 protrudes above the surface of the fixing grooves by 0.3-0.5 mm.

When the device is installed on the pipeline, the latter is placed in fixing grooves 6, parts I and 2 are clamped together with each other. As a result of shrinking parts I and 2, the pipeline is through a protective element

8 deforms the elastic and sensitive elements until it is completely covered by the locking grooves 6. In this case, the elastic elements 10 and 13 are compressed by 0.3-0.5 mm, and the sensitive element 9, made of a piezoelectric film, receives an initial deformation required for its operation.

I

With increasing pressure in the pipe 7, its outer diameter increases. The deformation of the pipeline through the protective element 8 is transmitted to the sensitive element 9, compressing it in one direction and simultaneously stretching in the other.

During deformation, the sensing element 9 generates an electric charge, the magnitude of which is proportional to the deformation of the outer diameter of the pipeline and, consequently, to the pressure inside it.

A similar pattern occurs simultaneously in both parts of the hull. As a result, from axis 3, electrically insulating

A flexible cable from the pipeline is used to remove an electrical signal proportional to the pressure in the pipeline. A common wire is the pipeline itself, electrically connected through a protective element to one of the poles of the sensing element.

As noted, the initial strain of elastic elements 10 and 13 in the direction radial to the axis of the pipeline is 0.3-0.5 mm. Since the stiffness of the protective element is much greater than the stiffness of the elastic elements, all deformation occurs on the latter. When compressing elastic elements in the radial direction, they increase their dimensions in the axial (along the axis of the pipeline) direction. The relationship between deformations in different directions is defined by the expression:

 R ,

where fo, p is the relative deformation in the axial and radial directions, respectively; C - Poisson's ratio of the material of elastic elements.

In the proposed device, the elastic element is divided into two parts by means of a rigid gasket 14, the thickness of the additional elastic element 13 being several times smaller than the thickness of the elastic element 10, determined by the roughness of the pipeline being tested, its curvature and equal, for example, to 0.5 mm element 10 equal to A mm. With such a ratio of sizes, the axial deformation of the ss of the additional elastic element 13, directly connected {with the protective element 8, is reduced by a factor of 9, which correspondingly reduces by the same amount and effort the tearing of the protective element from the intermediate elastic element. The result is improved device reliability.

The implementation of a rigid strip 14 of metal and electrical communication with the protective element 8 makes it possible to completely shield the sensitive element 9 from the influence of electrical interference and thereby increase the noise immunity of the device.

Claims (2)

1. A device for measuring pressure in a pipeline, comprising a housing consisting of two parts with symmetrical cavities made therein and connected with a hinge at one end and a clamp at the other, in which an elastic element made of electrically insulating material and a protective element made of foil are successively installed and fastened among themselves, characterized in that, in order to increase reliability, an additional elastic element and a rigid gasket are mounted between the sensitive and elastic elements and bonded to each other also with sensitive and elastic elements, respectively. 2. The device according to claim 1, about tl, which is the fact that, in order to improve noise immunity, a rigid gasket is made of metal in it and is connected to a protective element. L / FIG. 2 iO at y- / increased / 3 f Fig.d