JPH0592673U - Differential pressure / pressure transmitter - Google Patents

Abstract

(57) [Summary] [Purpose] If the fluid to be measured is a corrosive gas fluid,
Corrosion resistance at the liquid contact side of the barrier diaphragm is ensured in the required state, enabling appropriate pressure measurement. [Structure] The pressure acting on the barrier diaphragm is measured by the pressure transmitting sealed liquid sealed in the detector body. A diaphragm cover 30 for keeping corrosion resistance is closely arranged on the liquid contact side of the barrier diaphragm arranged on the outer surface side of the detection unit body. This diaphragm cover is formed of a soft elastic material having a gas-permeable metal layer 31 formed therein.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a differential pressure / pressure transmitter for detecting the pressure of various process fluids, and particularly to a wetted portion having corrosion resistance suitable for use when a corrosive fluid is used as the process fluid to be measured. Regarding the differential pressure / pressure transmitter provided.

[0002]

[Prior Art]

 For example, when measuring the flow rate of a fluid in a pipe, an orifice plate is provided in the pipe as a fluid resistance, and the pressure difference on the downstream side is calculated and measured based on a predetermined arithmetic expression. .. The detection unit in the differential pressure transmitter used for this type of differential pressure measurement has a configuration as schematically shown in FIG.

To briefly explain this, reference numerals 1 and 2 in the drawing denote a pair of left and right detection unit bodies that form a detection unit main body, and the back plate surfaces 1a and 2a formed on the outer surfaces of the left and right detection unit bodies have The high-pressure side and low-pressure side barrier diaphragms 3 and 4 each having a substantially corrugated disk shape are mounted. Each of the back plate surfaces 1a and 2a is formed in a circular shape having a corrugated cross section of substantially the same shape as the barrier diaphragms 3 and 4, and between the barrier diaphragms 3 and 4, the pressure measuring chambers 5 and 6 are formed. Is formed. Further, as described above, the high pressure PH on the upstream side of the pipe orifice and the low pressure PL on the downstream side are applied to the outer side surfaces of the barrier diaphragms 3 and 4, respectively.

A body inner chamber is formed between the detection unit bodies 1 and 2, and the body inner chamber is partitioned by a corrugated disc-shaped center diaphragm 7 into a pair of left and right chambers 7a and 7b. One chamber 7a is communicated with the pressure measuring chamber 5 on the high pressure side through through holes 8a, 9a for circulating the pressure medium and the enclosed circuit 10, and the other chamber 7b is communicated with the pressure measuring chamber on the low pressure side. 6 through the through holes 8b and 9b, and similarly to the enclosed circuit 11.

On the other hand, a header 12 composed of an inner cylinder 12a and an outer cylinder 12b made of stainless steel or the like is arranged at the upper ends of the outer circumferences of the detection unit bodies 1 and 2, and the sensor unit is provided inside thereof. 13 are provided. The sensor unit 13 includes a conventionally known semiconductor pressure-sensitive sensor 14 that partitions the enclosed circuits 10 and 11, and a protector that protects the pressure-sensitive sensor 14 and seals the open ends of the inner cylinder 12a and the outer cylinder 12b. It consists of 15 and.

In this case, the high pressure side enclosing circuit 10 communicates with the inside of the inner cylinder 12 a to apply the high pressure PH to the surface side of the pressure sensitive sensor 14. Further, the low-pressure side enclosed circuit 11 communicates with a passage formed in the protective body 15 or the like through a space passage 16 between the inner cylinder 12a and the outer cylinder 12b, so that the low-pressure PL is applied to the inner surface of the pressure-sensitive sensor 14. I'm giving. Silicon oil is provided in the conduction path between the pressure measuring chambers 5 and 6 and the high pressure side and low pressure side of the pressure sensitive sensor 14 through the through holes 8a, 9a; 8b and 9b and the enclosed circuits 10 and 11. Filled liquid 17 such as is filled as a pressure transmission medium. Reference numeral 18 in the drawing denotes a throttle member provided in the high pressure side and low pressure side pressure fluid passages and passages. Further, in the figure, 19A and 19B are covers which are assembled on the outside of the detection unit bodies 1 and 2 and which form a high pressure chamber and a low pressure chamber for introducing the measured fluid on the process side to act on the barrier diaphragms 3 and 4. It is a member.

In the differential pressure transmitter having such a configuration, when high pressure PH and low pressure PL are applied to the barrier diaphragms 3 and 4 from the process side, the differential pressure (PH-PL) at this time is detected by the semiconductor. Since it is added to the pressure sensor 14, the sensor 14 is deformed according to the differential pressure, and the amount of deformation is electrically extracted, amplified by an amplifier (not shown), and then displayed on a meter or the like or transmitted remotely. It was something.

In the differential pressure / pressure transmitter as described above, when a highly corrosive process fluid is used as the fluid to be measured, the pressure-measuring barrier diaphragms 3 and 4 serving as the liquid contact parts should have high corrosion resistance. It is required to be formed of the material that has it and to have corrosion resistance. However, some of the metal materials having such high corrosion resistance, such as titanium, monel, tantalum, and Hastelloy, cannot be press-molded into a barrier diaphragm shape, and also increase the cost. There is also a problem with.

Therefore, instead of forming such barrier diaphragms 3 and 4 from a corrosion-resistant metal material and exposing them directly to the fluid to be measured, these barrier diaphragms 3 and 4 are made of a general corrosion-resistant material ( For example, it has been conventionally performed that it is formed of stainless steel such as SUS316L) and the like, and that the protective covers 20, 20 such as Teflon are applied to the liquid contact side. That is, as is clear from FIG. 4, such a protective cover 20 is formed in substantially the same shape as the barrier diaphragms 3 and 4, and is provided along the barrier diaphragms 3 and 4. In this case, grease is applied to the contact surface between the protective cover 20 and the barrier diaphragms 3 and 4, and the protective cover 20 is integrated with the barrier diaphragms 3 and 4 in accordance with the pressure fluctuation on the liquid contact side. Moreover, it can be moved smoothly.

[0010]

[Problems to be solved by the device]

 However, when arranging the protective cover 20 such as Teflon as described above along the outer side surfaces of the barrier diaphragms 3 and 4, the following problems occur. That is, with the protective cover 20 as described above, the effect can be obtained when the fluid to be measured is a liquid, but since the gas permeates the gas, the protective cover 20 and the barrier diaphragms 3, 4 are Gas enters between the barriers, and the barrier diaphragms 3 and 4 corrode, and not only the corrosion resistance cannot be ensured, but also the movement accompanying the pressure fluctuation is hindered by the influence of gas etc. As a result, the pressure measurement malfunctions. There was a problem that caused.

As a solution to such a gas, it is considered to form a metal layer on the surface of the protective cover 20 by vapor deposition or the like. However, since such a metal layer is thin, the fluid to be measured is There was a problem in terms of life on the side in contact with the liquid. Further, such a metal layer formed by vapor deposition has irregularities on the surface, so that the barrier diaphragms 3 and 4 lack smoothness of movement and cause hysteresis.

The present invention has been made in view of such circumstances, and even when the fluid to be measured is a fluid such as a corrosive gas, the corrosion resistance at the wetted side portion by the barrier diaphragm is high. The purpose is to obtain a differential pressure / pressure transmitter that can ensure proper pressure measurement and perform appropriate pressure measurement.

[0013]

[Means for Solving the Problems]

 In order to meet such a demand, the differential pressure / pressure transmitter according to the present invention is in close contact with the liquid contact side of the barrier diaphragm disposed on the outer surface side of the detector body and has a metal layer formed therein. A diaphragm cover made of the above soft elastic material is arranged.

[0014]

[Action]

 According to the present invention, a diaphragm cover made of a soft elastic material in which a metal layer is formed is closely arranged on the liquid contact side of the barrier diaphragm. The metal layer of the diaphragm cover allows the measured fluid to be measured. Even if it is a corrosive gas, it can prevent its permeation to the barrier diaphragm side, ensure the corrosion resistance at the liquid contact side of the barrier diaphragm, and perform appropriate pressure measurement.

[0015]

【Example】

 1 and 2 show an embodiment of a differential pressure / pressure transmitter according to the present invention, and only a diaphragm cover 30 which is a main part thereof is shown. Note that the schematic configuration of the entire detection unit in the differential pressure / pressure transmitter is as illustrated in FIG. 3 described above, and the following description will be given with reference to this FIG.

Now, according to the present invention, in the detection part in the differential pressure / pressure transmitter as shown in FIG. 3, the barrier diaphragms 3, 4 arranged on the outer surface side of the detection part bodies 1, 2 are A characteristic is that a diaphragm cover 30 made of a soft elastic material having a metal layer 31 formed therein is closely arranged on the liquid contact side.

Here, the diaphragm cover 30 characterizing the present invention is formed of a soft elastic material such as a synthetic resin material such as Teflon according to the shape of the barrier diaphragms 3 and 4, and the above-mentioned Teflon or the like. A gold-plated film, an aluminum film, or the like is provided as a metal layer 31 between the resin layers 32, 32 formed by.

In particular, such a metal layer 31 has a gas permeability coefficient much lower than that of a resin material, so that even if the fluid to be measured is a corrosive gas fluid, its barrier diaphragm is used. It is possible to prevent transmission to the 3 and 4 sides.

The diaphragm cover 30 having the metal layer 31 as described above is formed, for example, on a Teflon plate forming the resin layer 32 on one side with a gold plating film or an aluminum film by plating, vapor deposition, lining or coating, and the metal layer 31. Then, a Teflon material is formed on the surface of the metal layer 21 as the other resin layer 32 by lining or molding, and can be easily formed.

According to such a configuration, the diaphragm cover 30 made of a soft elastic material in which the metal layer 31 is formed is closely arranged on the liquid contact side of the barrier diaphragms 3, 4. Moreover, the metal layer 31 of the diaphragm cover 30 can reliably prevent permeation to the barrier diaphragms 3 and 4 side even if the measured fluid is a corrosive gas gas. Corrosion resistance can be secured at the liquid contact side of 3 and 4, and the required pressure can be measured.

Further, in the diaphragm cover 30 having the metal layer 31 inside and the resin layers 32, 32 on both sides thereof, in order to obtain slippage with the barrier diaphragms 3, 4 side, etc., It also has the advantage of eliminating the need to apply grease.

It should be noted that the present invention is not limited to the structure of the above-described embodiment, and the shape, structure, etc. of each part including the detection part structure of the differential pressure / pressure converter can be appropriately modified and changed. Various variants are conceivable.

[0023]

[Effect of the device]

 As described above, according to the differential pressure / pressure transmitter of the present invention, a soft elastic material having a metal layer formed inside is formed on the liquid contact side of the barrier diaphragm disposed on the outer side surface of the detection unit body. Despite the simple structure, the metal layer inside the diaphragm cover made of soft elastic material that is in close contact with the liquid contact side of the barrier diaphragm prevents the fluid to be measured. Even if it is a corrosive gas, it is prevented from permeating to the barrier diaphragm side, which ensures proper and reliable corrosion resistance at the liquid contact side of the barrier diaphragm, and this diaphragm cover is integrated with the barrier diaphragm. There are various practically excellent effects that can be appropriately moved to perform proper and reliable pressure measurement.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of an essential part of a diaphragm cover, which shows an embodiment of a differential pressure / pressure transmitter according to the present invention.

FIG. 2 is a cross-sectional view of main parts showing a part of FIG. 1 in a further enlarged manner.

FIG. 3 is a schematic cross-sectional view for explaining a conventional example of a detector structure of a differential pressure / pressure transmitter suitable for applying the present invention.

FIG. 4 is a schematic sectional view showing a protective cover of the barrier diaphragm used in FIG.

[Explanation of symbols]

 1 Detection Body 2 Detection Body 3 Barrier Diaphragm 4 Barrier Diaphragm 5 Pressure Measuring Chamber 6 Pressure Measuring Chamber 7 Center Diaphragm 14 Pressure Sensitive Sensor 17 Pressure Transmitting Liquid 30 Diaphragm Cover 31 Metal Layer 32 Resin Layer

Claims (1)

[Scope of utility model registration request] 1. A differential pressure / pressure transmitter for measuring a differential pressure by moving a pressure transmitting filled liquid filled in a detection body, wherein a contact of a barrier diaphragm disposed on an outer surface side of the detection body. A differential pressure characterized by having a diaphragm cover made of a soft elastic material that is placed in close contact with the liquid side, and forming a metal layer inside the diaphragm cover.
Pressure transmitter.