Jerguson® FlashProof™: Solving False Readings in Boiling Fluids and Dirty Service

Apr 22, 2024
3 min read

Updated: Aug 13

The Jerguson FlashProof design addresses two potential problems that may occur with standard level indicators: boiling fluids and flashing vapors, and dirty or viscous service. Both problems share a common root cause - something interfering with the float's ability to move freely and accurately inside a standard-size chamber - and FlashProof solves both with the same core design change.

The Problem: Boiling Fluids and Flashing Vapors

In a standard-size chamber, entrained gas released under low pressure can build up directly beneath the float, creating false level readings. As boiling or flashing vapors try to rise to the surface, they disturb the float's position, causing the indicator to show a level that doesn't actually reflect the true liquid surface.

The Solution: Larger Chamber with Guide Rods

By employing a larger 3-inch Schedule 40 pipe and two internal guide rods, entrained gases that build up under the float can harmlessly escape rather than disturbing float position. The float is held to one side of the chamber to ensure an optimized magnetic field in close proximity to the indicator, transmitter, or switches - providing an accurate float level and indicator reading even as gas continues to vent past it.

The Problem: Dirty or Viscous Service

The Jerguson FlashProof design also addresses problems caused by dirty or viscous service. In a standard gage, dirt, sludge, or wax-like solids present in the process fluid can potentially bind the float, causing the level to appear unchanged even as actual liquid level continues to rise or fall - a particularly dangerous failure mode, since the gage keeps displaying a reading without any obvious sign that it's stuck.

The Solution: Oversized Chamber and Bypass Zone

The use of an oversized 3-inch Schedule 40 chamber creates additional space to prevent the float from binding when dirt, sludge, or wax-like solids are present. Additionally, the bypass zone allows the gage to be flushed without removing the float from the column - meaning routine cleaning doesn't require a full disassembly just to clear accumulated material.

Full Specification Overview

Larger diameter chamber with float guides
Complies with ASME B31.1 and ASME B31.3
Available with the full range of Jerguson indicators, transmitters, and switches
3-inch Schedule 40 pipe chamber as standard
Schedule 80 and 120 available for high-pressure applications
Size range from 12 inches to 240 inches (305mm to 6096mm) vessel centers, with longer units available by consulting the factory
Specific gravity minimum: 0.36
Pressure class rating up to 1919 PSIG (132 BarG) at 100°F (37°C) per ASME B31.3, with higher pressures available
Temperature range: -325°F to 1000°F (-198°C to 538°C)

That temperature range - spanning nearly 1,325 degrees Fahrenheit - combined with a pressure rating approaching 2,000 PSIG, reflects a design built for genuinely demanding process conditions rather than a narrow standard service window.

Why One Design Solves Two Different Problems

It's worth noting that boiling/flashing fluids and dirty/viscous service are, on the surface, very different application challenges. What connects them is that both interfere with the float in the same physical location - directly around and beneath it - which is exactly why an oversized chamber with guide rods addresses both: more space and a controlled float position give entrained gas somewhere to go and give solids somewhere to settle without binding the float, regardless of which specific problem a given application presents.

Applications

FlashProof design is especially valuable for:

Refining & Petrochemical: Boiling or flashing hydrocarbon streams
Chemical Processing: Viscous or solids-laden process fluids
Any Application with a History of False or Stuck Readings: Where a standard-size chamber has struggled with fluid behavior
High-Temperature, High-Pressure Service: Given the extended temperature and pressure ratings available