Bourdon Tube Pressure Gauge (Liquid-Filled / Dry, 4" Dial)

The Visual Sentinel of Hydraulic Stability and Safety

In pressurized infrastructure networks—such as main water loops, HVAC chiller lines, and NFPA-compliant fire pump houses—visual tracking of system energy is vital. Pumps running against closed lines, clogged sediment strainers, or undetected line ruptures instantly alter system equilibrium. A Pressure Gauge acts as the primary field monitoring point, providing maintenance technicians and building safety inspectors with immediate visual verification of baseline operating parameters, testing thresholds, and surge conditions.

The gauge operates entirely on mechanical principles via a precision-crafted internal Bourdon Tube. This C-shaped hollow metal tube connects directly to the incoming fluid pipeline. As water or gas enters the tube, the rising internal pressure forces the curved metal structure to slightly straighten out. This minute physical deflection is captured by a low-friction mechanical gear movement that translates the linear motion into a rotational sweep across the dial face. Because it functions completely without external electrical power, the gauge provides reliable safety readings even during complete facility power blackouts or emergency situations.

Core Configuration Options: Liquid-Filled vs. Dry

To match specific installation locations and mechanical stress levels, the gauge is available in two distinct formats:

1. Glycerin/Silicone Liquid-Filled Gauges

• Damping Pulsation and Vibration: The internal casing is entirely filled with high-purity liquid glycerin or silicone oil. This liquid dampens the internal pointer movement, completely eliminating needle flutter caused by high-vibration mechanical rooms or rapid pump piston cycles.

• Lubrication and Protection: The filling fluid continuously lubricates the internal gear movement, prevents internal condensation behind the lens, and shields the mechanism from aggressive atmospheric moisture and salt-water corrosion.

2. Dry Gauges

• Standard Environmental Duty: Best for stable, low-vibration environments, dry air pipelines, or extreme ambient temperature zones where filling liquids might freeze or become overly viscous.

Key Performance Features

• Vibration-Proof Stainless Steel Armor: Enclosed inside a heavy-duty Grade 304 or 316 stainless steel casing, providing complete protection against physical impact, oil film buildup, and rust.

• Dual-Scale High-Visibility Dial: Outfitted with an expansive, crisp white aluminum dial outputting both PSI (black scale) and bar/kPa (red scale), allowing for seamless global code cross-referencing.

• Integrated Safety Blowout Device: Features a flexible rubber blowout plug on the top or back of the case. In the rare event of an internal Bourdon tube rupture under extreme overpressure, the plug pops open to safely vent internal pressure out the back, preventing the front glass window from shattering forward onto operators.

• Overpressure Safety Margin: Engineered with a robust mechanical stop that allows the internal sensing element to tolerate brief overpressure spikes up to 130% of the full-scale value without shifting its factory calibration.

• Strict Code Compliance: Manufactured and tested to meet international instrumentation benchmarks, including ASME B40.100 Grade AA accuracy standards ($\pm1.0\%$ accuracy margin across the entire range).

Ideal Infrastructure Applications

• Fire Pump Houses (NFPA 20): Mandatory installation on pump suction lines (compound gauges tracking vacuum/pressure) and pump discharge manifolds to track system churn and peak flow ratings.

• HVAC Chilled and Hot Water Loops: Positioned upstream and downstream of balancing valves and chillers to track differential pressure metrics.

• Municipal Water Booster Stations: Providing reliable, visible field pressure checks along municipal utility junction boxes and reservoir transfer ports.

Technical Performance MatrixEngineering MetricHeavy-Duty Liquid-Filled GaugeStandard Dry Utility GaugeDial Face Nominal Diameter$4"\text{ (100 mm) standard}$ / $2.5"\text{ (65 mm)}$$2.5"\text{ (65 mm) or }4"\text{ (100 mm)}$Accuracy Class Rating$\pm1.0\%\text{ of Span (ASME Grade 1A)}$$\pm1.6\%\text{ or }\pm2.5\%\text{ of Span}$Standard Range Profiles0–300 PSI (0–20 bar) / 0–400 PSI standard0–100 PSI / 0–160 PSI / 0–600 PSI optionsConnection Entry TypeBottom Mount or Lower Back Panel MountBottom Mount or Center Back MountThread Interface Profile$1/4"\text{ or }1/2"\text{ NPT / BSP Male Thread}$$1/4"\text{ or }1/8"\text{ NPT / BSP Male Thread}$Internal Sensing MetallurgyAISI 316 Stainless Steel / Phosphor BronzeBrass / Copper Alloy Bourdon TubeCase Shell CompoundGrade 304 Stainless Steel (IP65 Sealed)Black Painted Steel / Polycarbonate BaseWindow Lens MatrixLaminated Safety Glass / Tough AcrylicClear Polycarbonate / Instrument GlassStandard Procurement Package Components

• Complete Pressure Gauge Assembly (Factory Calibrated and Sealed)

• Pre-installed External Rubber Safety Blowout Vent Plug

• Individual Factory Calibration Accuracy Verification Certificate

• Optional System Add-ons: In-line Isolation Needle Valves, Pulsation Dampening Snubbers (Pigtail Syphons for steam/hot water protection), and Chrome Flange Panel-Mounting Rings (Sold Separately)