Instrumentation

Different types of Pressure gauges

Diaphragm pressure gauges

Diaphragm pressure gauges may only be used to display the pressure of high-viscosity or crystallizing media

  • This pressure gauge is widely used to measure pressure of a reactor or closed container.

    Principle:
    When pressure is applied on either sides of the tight diaphragm, by which it gets deflected. This deflection of the diaphragm is proportional to the differential pressure across it. Thus differential pressure across the diaphragm can be measured in terms of its deflection.

    Construction and working:
    Diaphragm gauge uses metallic or non metallic diaphragms along with the pointer mechanism.

    1) Metallic diaphragms: These elements are flexible circular discs, either flat or corrugated. These elements convert pressure signal to pointer deflection.
    The metal is heat treated before forming a diaphragm to produce maximum elastic limit. After forming, the diaphragms are heat treated to relive internal stresses. A diaphragm is usually designed so that the deflections versus pressure characteristics are as linear as possible over a specified pressure range. Metals used are brass, beryllium-copper, stainless steel and phosphor-bronze.

  • 2) Non metallic diaphragms: very bendable diaphragms are used and so they can be utilized to measure vacuum and low pressures available. Non metallic materials used are synthetic rubber, neoprene, leather, Teflon, nylon or decron.

    Pressure range:
    For non-metallic diaphragm 0 to 10 inch water

  • For metallic diaphragm
    Minimum= 0 to 2 inch of water
    Maximum=0 to 400 psi

    Advantages:
    Small in size and cheaper.
    2. By using corrosion resistant material it has long life.
    3. We can obtain perfect linearity functions.
    Limitations:
    1. Cannot be used for high pressure.
    2. Vibration will affect the reading.

Differential pressure gauges

Differential pressure gauges are particularly intended for the monitoring of differential pressures in filter systems, pumps and pipeline systems in the heating, ventilation and air-conditioning sector, technical building equipment and in the water management industry. Apart from the display of the differential pressure, these applications require, as a rule, the display of the current working pressure. For this reason, a working pressure gauge is integrated in the DELTA-plus differential pressure gauge as a standard feature.   An additional measuring point involving additional expenses for piping and mounting is thus no longer required. The white dial of the working pressure gauge distinctly stands out against the blue background of the display of the differential pressure gauge, thus enabling a quick and  safe reading of both measurement parameters. The ranges of 0 … 250 mbar up to 0 … 25 bar provide the  measuring ranges, which are required in many different applications. The sturdy and compact design of the differential pressure gauge makes it possible to use it even under tough industrial ambient conditions.

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