Diaphragm-Seal Pressure Gauge
Application
Diaphragm-Seal pressure gauges are widely used in petroleum, chemical, alkali-making, chemical fiber, pharmaceutical, food, textile and other technological processes. It con be used to measure the pressure of media with strong corrosion, high temperature, high viscosity, crystalline, easy to solidify and with solid floating matter, as well 05 to measure the pressure of some media that can not directly enter the general pressure gouge, that is not easy to clean the precipitated material and prevent its accumulation.
These problems can be solved by adopting a diaphragm-seal pressure gouge, which composed of a diaphragm isolator and a general pressure gauge.
Theory
When the pressure P of the measuring medium acts on the diaphragm, the diaphragm deforms and squeezes the sealing liquid of the pressure measuring system, producing a pressure of P-△P. When the rigidity of the diaphragm is small enough,△P will also be small, and the pressure inside the pressure measuring system is close to the pressure of the measuring medium.
Working Theory
Operation
■When installing or disassembling, don't pull the case of the gauge by hand, use a special wrench to install or disassemble.
■When selecting models, pay attention to confirm whether the medium matches the material of the gauge.
■The pressure gauge should be installed horizontally or vertically.
■The normal working environment temperature of the pressure gauge is -40°C~+ 70°C, and the relative humidity is not more than 85%.
Liquid Level
For diaphragm-seal pressure gauge with hose connection, due to the different installation position of compression part and pressure gauge, the influence of liquid level difference △P as shown in the figure below will be formed.
Model Code
lf you have other requirements, please confirm with our company's technical department before customizing.
Pressure Range & Accuracy
Diaphragm-seal Pressure Gauge's Temperature
The influence of the working temperature is related to the expansion coefficient of sealing liquid, the rigidity of diaphragm seal and the temperature of compression part. When the working temperature of the gauge deviates from 20土5℃, the maximum change rate of indication value affected by temperature.The rigidity shall not be more than 0.1% °C and the flexibility (remote connection type) shall not be more than 0.1 ± 0.025L% ℃ (L-length of the hose: m). When making diaphragm seal pressure gauge, we should pay attention to choose suitable sealing liquid according to different use environment.
Sealing liquid
To ensure the reliability and safety of diaphragm seal pressure gauge, appropriate sealing liquid should be selected according to different applications.
|
Sealing Liquid |
Temperature Range |
Specific Weight g/cm3 |
Volume expansion coefficient 1/℃ |
Use |
|
Heavy viscous silicone oil |
-10~200℃ |
1.07 |
0.95×10-3 |
High temperature use |
|
low viscous silicone oil |
-30~100℃ |
0.94 |
1.08×10-3 |
General use |
|
glycerine solution |
-5~100℃ |
1.27 |
0.61×10-3 |
Food use |
Corrosion Resistance
The corrosion resistance of diaphragm seal pressure gauge can be ensured by selecting the materials of diaphragm seal, flange and sealing gasket which contact with measuring medium.
Diaphragm materials: 0Cr17Ni12Mo2(SUS316L), Monel alloy(Cu30ni70), Hastelloy(H276C), Tantalum(Ta)or Poly Tetra Fluoroethylene(PTFE/Teflon).
Flange material:SUS304, SUS316, with Poly Tetra Fluoroethylene ( PTFE/Teflon) lining.
Diaphragm-seal Material
|
Corrosion Medium |
Diaphragm Material |
|||||
| Tin bronze
（QSn6.5-0.4) |
SUS316 |
Tantalum (Ta) |
Monel
(Ni70Cu30) |
Hastelloy
(HC) |
Teflon(F4) |
|
|
Vitriol (H2SO4） |
√ |
△ |
〇 |
√ |
√ |
√ |
|
Nitric acid (HNO3) |
× |
√ |
〇 |
× |
√ |
√ |
|
Muriatic acid (HCl) |
△ |
× |
〇 |
× |
√ |
√ |
| Phosphoric acid (H3PO4) |
√ |
√ |
〇 |
√ |
√ |
√ |
|
Acetic acid(CH3COOH) |
√ |
√ |
〇 |
√ |
〇 |
√ |
|
Sodium hydroxide (NaOH) |
△ |
〇 |
△ |
〇 |
〇 |
√ |
|
Sodium Carbonate (Na2CO3） |
〇 |
〇 |
〇 |
〇 |
√ |
√ |
|
Natrium Bicarbonate (NaHCO3) |
√ |
〇 |
〇 |
〇 |
〇 |
√ |
|
Chlorine(Cl2) |
dry：√ |
dry：√ |
〇 |
dry：√ |
√ |
√ |
|
Bromine(Br2) |
dry：△ |
dry：× |
〇 |
dry：〇 |
〇 |
√ |
|
Ammonia（NH3） |
× |
√ |
× |
× |
〇 |
√ |
|
Sea Water（30%NaCl） |
√ |
√ |
〇 |
〇 |
〇 |
√ |
|
Instruction: 〇-best △-use with condition √-ok X-no use |
||||||
Choose Flange
Connector Size
Demo Mode
Stainless steel diaphragm seal pressure gauge, radial installation, open convex flange, the diaphragm seal material is tantalum, the range is 0-1MPa, the flange standard is Chemical Industry Standard HG/ T20592-2009 DN25 PN1.6, flange material 304.
Order Remarks
Safety Warning
For safety, please select the correct model of product. lf the product is selected or used improperly,it may cause property loss or personal injury. The designer and user of the system should be fully responsible for selecting the correct product and using the product in the correct way.