A Historical Perspective
From Aristotle to Hawking
Force & Its Effects
Measurement Limitations
The Strain Gage
Sensor Designs
Measuring Circuits
Application & Installation
Process Pressure Measurement
From Mechanical to Electronic
Transducer Types
Practical Considerations
High Pressure & Vacuum
High Pressure Designs
Very High Pressures
Vacuum Instrumentation
Pressure Gauges
& Switches
Pressure Gauge Designs
Protective Accessories
Pressure Switches
Force, Acceleration,
& Torque
Force Sensors
Acceleration & Vibration
Torque Measurement
Load Cell Designs
Operating Principles
New Sensor Developments
Strain Gage Configurations
Weighing Applications
Weighing System Design
Installation & Calibration
Specialized Installations
Information Resources
List of Figures
Data Tables
Technical Learning Home

Pressure Gauge Designs
Two common reasons for gauge (and switch) failure are pipe vibration and water condensation, which in colder climates can freeze and damage the gauge housing. Figure 5-1 illustrates the design of both a traditional and a more reliable, "filled" pressure gauge. The delicate links, pivots, and pinions of a traditional gauge are sensitive to both condensation and vibration. The life of the filled gauge is longer, not only because it has fewer moving parts, but because its housing is filled with a viscous oil. This oil filling is beneficial not only because it dampens pointer vibration, but also because it leaves no room for humid ambient air to enter. As a result, water cannot condense and accumulate.

Figure 5-2: Pressure Gauge Accessories

  Available gauge features include illuminated dials and digital readouts for better visibility, temperature compensation to correct for ambient temperature variation, differential gauges for differential pressures, and duplex gauges for dual pressure indication on the same dial. Pressure gauges are classified according to their precision, from grade 4A (permissible error of 0.1% of span) to grade D (5% error).

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