Mainly there are three types of gauge protectors:
• Pulsation protection and vibration protection.
• Temperature protection.
• Chemical protection.
• PULSATION AND VIBRATION PROTECTION
The area surrounding the bourdon tube is filled with transparent Liquid, normally glycerin. This protects the internal mechanisms against damage from vibration. This also damps the movement of the pointer from small transient fluctuations.
Pressure gauge snubbers are used to protect the pressure gauge from the effects of pulsating pressure. Porous snubbers are the most common type. Adjustable snubbers are provided with an adjustable needle valve that enables the operator to restrict the flow as operating conditions may demand even when the snubber is in service. Pressure gauge snubbers are effective for applications with pressure above 5 psi.
• TEMPERATURE PROTECTION
As the bourdon tube may be damaged by high temperature, it is common practice on steam systems to install the gauge at the end of a syphon tube. The siphon tube is filled with water which transmits the pressure of the working fluid to the bourdon tube. The most common forms of syphon tubes are the U type and ring type. The ring type is used on horizontal pipelines where there is sufficient space above the pipe, and U type is used when mounting the gauge on a vertical pipe line or horizontal pipe line where there is not sufficient space for a ring syphon.
• CHEMICAL PROTECTION
DIAPHRAGM SEALED PRESSURE GAUGE
A diaphragm seal is a flexible membrane that seals and isolates an enclosure. The flexible nature of this seal allows pressure effects to cross the barrier but not the material being contained. The pressure which is received by the diaphragm is transmitted to primary sensing element and variable conversion element is deformed under the pressure to rotate the pointer.