The Diaphragm Pressure Gauge is suitable for measuring the pressure of highly corrosive, high-temperature, high-viscosity, easily crystallizing or solidifying media, and media containing suspended solids. It is also suitable for applications where direct contact between the measured medium and conventional pressure instruments must be avoided, sediment accumulation must be prevented, and easy cleaning is required.
Product Overview
The Diaphragm Pressure Gauge consists of a diaphragm seal and a general-purpose pressure measuring instrument.
The main connection methods between the diaphragm pressure gauge and equipment include threaded connections, flange connections, and sanitary clamp connections.
Diaphragm Pressure Gauges are mainly used to measure fluid pressure in industrial processes such as petrochemicals, alkali production, chemical fiber manufacturing, dyeing and chemical processing, pharmaceuticals, food processing, and alkali production.
Structure and Working Principle of Diaphragm Pressure Gauges
When the pressure P of the measured medium acts on the diaphragm, the diaphragm deforms and compresses the sealing fluid in the pressure measuring system, generating a pressure of P-△P. When the diaphragm stiffness is sufficiently low, △P is also small, so the pressure generated in the measuring system is approximately equal to the pressure of the measured medium.
Technical Specifications
1. Temperature Characteristics:
Since the diaphragm pressure gauge system uses a filling fluid to transmit pressure, the thermal expansion coefficient of the filling fluid causes the indicated pressure to increase as the temperature of the pressure-sensing section rises. The temperature effect depends on the volumetric thermal expansion coefficient of the filling fluid, diaphragm stiffness, and temperature of the pressure-sensing section. This effect is particularly significant for low-range pressure instruments. Generally, the temperature error of the pressure-sensing section must not exceed 0.1%/℃. Therefore, the total temperature effect of a diaphragm pressure gauge is generally the sum of the temperature effect of the general-purpose instrument and that of the pressure-sensing section of the diaphragm seal.
2. Accuracy Classes: Class 1.6; Class 2.5
3. Measurement Range (MPa) - Threaded Connection: ~0.1~0/0~60/0~100
Flange Connection: ~0.1~0/0~25
Sanitary Clamp Type: ~0.1~0/0~2.5
4. Diaphragm Materials: 0Cr17Ni12Mo2 (316); Monel Alloy (Cu30Ni70); Hastelloy (p76C); Tantalum (Ta); and Fluoroplastic (F4).
5. Internal Filling Fluid: (1) Silicone Oil; (2) Other filling fluids according to customer requirements.
6. Operating Conditions:
(1) Temperature: Ambient Temperature -20~+55℃; Measured Medium Temperature -20~+55℃
(2) Operating Pressure: Static Load: Up to 3/4 of the upper measurement limit.
(3) Alternating Load: Up to 2/3 of the upper measurement limit.
(4) Short-Term Pressure: Up to the upper measurement limit.
7. Connection Dimensions
(1) Threaded Connection: M20*1.5 (G3/8″ G1/2″)
(2) Flange Connection:
A. Ministry of Machinery Industry Standard JB81-94 "Flat-Welded Steel Flanges"
B. Ministry of Chemical Industry Standard "Acid-Resistant Flat-Welded Steel Flanges"
C. Customized According to Customer Requirements
8. Instrument Outer Diameter: φ60mm; φ75mm; φ100mm; φ150mm
9. Applicable Standard: JB/T8624-1997
Explanation of Liquid Level Difference
Particularly for diaphragm pressure gauges equipped with flexible connecting tubes, differences in the mounting positions of the pressure-sensing section and the general-purpose pressure gauge can produce a hydrostatic pressure difference △P, as illustrated in the diagram.
Corrosion Resistance
The corrosion resistance of the diaphragm pressure gauge can be ensured by selecting appropriate materials for the isolation diaphragm, flange, and sealing gasket that come into contact with the measured medium.
Diaphragm Materials: 0Cr17Ni12Mo2 (316); Monel Alloy (Cu30Ni70); Hastelloy (p76C); Tantalum (Ta); and Fluoroplastic (F4).
Flange Materials: Stainless Steel 0Cr17Ni12Mo2 (316); Stainless Steel Lined with Fluoroplastic (316+F4).
Sealing Gasket Materials: Nitrile Rubber; Fluororubber; Silicone Rubber; and Fluoroplastic.
Model Designation Examples
Example 1: Y-100B/SR/MF(A)316/4MPa/50-4.0HGJ46
The general-purpose instrument is a Y-100B Stainless Steel Pressure Gauge with an SR heat-dissipating connection. It uses an MF open raised-face flange diaphragm seal. The diaphragm seal (flange) is made of carbon steel, and the diaphragm is made of 316 stainless steel. The measurement range is 0~4 MPa, and the flange designation is 50-4.0HGJ46.
Example 2: YSG-2/ZMG(B) Hastelloy/1MPa/20-4.0Hgj47
The general-purpose instrument is a YSG-2 Inductive Pressure Transmitter with a direct connection. It uses an MG I-shaped flange. The diaphragm seal (flange) is made of 1Cr18Ni9, and the diaphragm is made of Hastelloy. The measurement range is 0~1 MPa, and the flange standard is 20-4.0HGJ47.
Example 3: Y-100B/SR/ML 316/4MPa/M20*1.5
The general-purpose instrument is a Y-100B Stainless Steel Pressure Gauge with an SR heat-dissipating connection. It uses an ML threaded diaphragm seal made of stainless steel, with a 316 stainless steel diaphragm. The measurement range is 0~4 MPa, and the thread specification is M20*1.5.
Ordering Information
1. When placing an order, please specify the model, product name, measurement range, measured medium, operating temperature, connection type and dimensions, and accuracy class.
2. If there are any special requirements, please provide detailed information when placing the order.
3. Do not disassemble the diaphragm pressure gauge or replace its fitted instrument, as leakage of the filling fluid may affect its performance.
4. Before placing an order, select the appropriate pressure gauge according to the characteristics of the measured medium, such as corrosiveness, tendency to solidify, and tendency to crystallize. For corrosive media, select a stainless steel pressure gauge or a diaphragm pressure gauge with an isolation diaphragm made of a suitable corrosion-resistant material. For high-temperature applications, use a high-temperature melt diaphragm pressure gauge. For general media, such as water and gases that are non-corrosive to copper or copper alloys, a standard pressure gauge may be used.