Brief Description: Diaphragm pressure gauges are mainly used in the petroleum, chemical, chemical fiber, food, pharmaceutical and other industrial sectors to measure the pressure of media that are highly corrosive, high-temperature, highly viscous, prone to crystallization, solidification, and solid particles, as well as for pressure testing where some measuring media cannot directly enter general-purpose pressure instruments and prevent sediment accumulation and are easy to clean.
Diaphragm pressure gauges are mainly used in industries such as petroleum, chemical, chemical fiber, food, pharmaceutical, and other industries to measure the pressure of media with strong corrosion, high temperature, high viscosity, easy crystallization, easy solidification, and solid particles, as well as for pressure testing where some measuring media cannot directly enter general-purpose pressure instruments and prevent sediment accumulation and are easy to clean.
The diaphragm pressure gauge consists of three major parts: a general-purpose pressure gauge, a connector, and a diaphragm isolator (see the following composition diagram):
Schematic Diagram of Diaphragm Pressure Gauge Composition
Model representation
Structural principle
When the pressure of the measured medium acts on the isolation membrane, the membrane generates deformation and compresses the sealing fluid in the pressure measuring system of the pressure instrument, causing the elastic elements in the pressure instrument to generate corresponding elastic deformation. After transmission and amplification by the transmission structure, the pressure value is indicated on the dial by the indicating device.
Main technical characteristics
·Temperature characteristics of diaphragm pressure gauges
The total temperature influence of diaphragm pressure gauges is generally universal
Temperature influence amount of pressure instrument and pressure part temperature of diaphragm isolator
The sum of the degree influence quantities, as specified by the temperature error of the general pressure part
Not more than 0.1%/℃.
·Level difference of diaphragm pressure gauge
Especially for diaphragm pressure gauges with flexible connecting pipes, the installation position of the pressure part and the general-purpose pressure instrument is not on the same horizontal plane, which will produce the influence amount △ P of the liquid level difference as shown in the figure.
When the pressure of the measured medium acts on the isolation membrane, the membrane generates deformation and compresses the sealing fluid in the pressure measuring system of the pressure instrument, causing the elastic elements in the pressure instrument to generate corresponding elastic deformation. After transmission and amplification by the transmission structure, the pressure value is indicated on the dial by the indicating device.
Main technical characteristics
·Temperature characteristics of diaphragm pressure gauges
The total temperature influence of diaphragm pressure gauges is generally universal
Temperature influence amount of pressure instrument and pressure part temperature of diaphragm isolator
The sum of the degree influence quantities, as specified by the temperature error of the general pressure part
Not more than 0.1%/℃.
·Level difference of diaphragm pressure gauge
Especially for diaphragm pressure gauges with flexible connecting pipes, the installation position of the pressure part and the general-purpose pressure instrument is not on the same horizontal plane, which will produce the influence amount △ P of the liquid level difference as shown in the figure.
·Selection of sealing fluid
To ensure the reliability and safety of diaphragm meters, appropriate sealing fluids should be selected according to different applications.
Sealing fluid | Pressure part temperature range | Specific gravity g/cm3 | Body expansion series number 1/℃ | use |
High viscosity silicone oil | -1～200℃ | 1.07 | 0.95×10-3 | For high temperature use |
Low viscosity silicone oil | -30～100℃ | 0.94 | 1.08×10-3 | General use |
Glycerin aqueous solution | -5～100℃ | 1.27 | 0.61×10-3 | For food |
plant oil | -5～100℃ | 0.93 | 1.03×10-3 | For food |
Fluoro oil | -30～150℃ | 1.93 | 0.75×10-3 | Hydrogen, oxygen |
Diaphragm unit flange size
1、Open Raised Face Flange
code name | Upper Range Value P (MPa) | Recommended flange standard code | Raised face flange size (mm) | Dimensional drawings |
D | K | d | f | L | C | B |
MF1 | 4 | JIS-10/20K 50A | 155 | 120 | 100 | 3 | 19 | 18 | 50 | Figure 1 |
4 | 50-1.0/4.0 HGJ46 | 160 | 125 | 100 | 3 | 19 | 18 | 50 |
4 | ANSI-2B 150Ib | 152 | 121 | 92.1 | 3 | 19 | 18 | 2" |
4 | ANSI-2B 300/100Ib | 165 | 127 | 92.1 | 3 | 19 | 18 | 2" |
6-10 | 25-10.0 HGJ47 | 125 | 89 | 50.8 | 7 | 20 | 20 | 25 | Figure 2 |
6-10 | 50-10.0 HGJ47 | 165 | 127 | 92.1 | 3.5 | 20 | 26 | 50 |
16-25 | 20-25.0 HGJ53 | 130 | 89 | 43 | 7 | 22 | 20 | 25 |
MF | 4 | 25-4.0 DIN | 115 | 85 | 65 | 3 | M12 | 26 | 25 | Figure 3 |
※Can be manufactured according to the flange standard size provided or specified by the user
Figure 3 (Upper Range Value ≤ 4MPa) [code MF]
2、I-shaped raised face flange [code MG]
Upper range value: ≤ 4MPa
Recommended flange standard code | measurement |
DN | d1 | K | d2 | L |
JSI-10/25K25A | 25 | 125 | 90 | 70 | 19 |
JSI-10/20K20A | 20 | 100 | 75 | 58 | 15 |
JSI-10/20K15A | 15 | 95 | 70 | 52 | 15 |
ANSI-1B-150IB | 1" | 108 | 79.4 | 50.8 | 15.7 |
ANSI-1B-300/600Ib | 1" | 124 | 88.9 | 50.8 | 19.1 |
20-1.0/4.0/OHGJ47 | 20 | 105 | 75 | 56 | 14 |
※Can be manufactured according to the flange standard size provided or specified by the user
3、Threaded joint type [code ML]
Upper range value: ≤ 60MPa
4、Bolt type diaphragm isolator [code MZ]
Measuring range: 1~25MPa
Diaphragm and diaphragm seat material: OCr17Ni12Mo2 [316]
5. Clamp type diaphragm isolator [code MC]
6. Nut type diaphragm isolator [code MN]
7. Rectangular flange diaphragm isolator [code MH]
Note: Please refer to the special page of sanitary diaphragm pressure gauge for details of types 5, 6, and 7.
Connector overall dimension (unit: mm)
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