EFP Series standard void fraction /steam quality blade probe.

EFP Series void fraction / steam quality blade probe made of Inconel® 625 0.050 in. (1.3 mm) material, designed to be welded in place. The conductor is Inconel®-clad. This probe is good for long-term exposure at or above 550 °F (288 °C).

EFP Series void fraction / steam quality blade probe with minimal frontal cross-section in a low-pressure bubbly flow test chamber.

EFP Series void fraction / steam quality blade probe in a low-pressure bubbly /slug flow test chamber. This probe is able to determine local void fraction and steam quality in bubbly / slug flow to better than ±1% at sampling rates of 500-1000 Hz. With two probes, this temporal resolution allows accurate autocorrelation determination of slip velocity. Probe dimensions are customizable to optimize sampling volume, and probe frontal cross-section is minimal.

EFP Series coaxial liquid level probe.

EFP Series coaxial liquid level probe. In many boiling or frothing environments, this probe can be used to simultaneously determine froth-height, measure froth-liquid interface, estimate void fraction / steam quality at multiple levels, and determine true collapsed liquid level of the remaining fluid column. In high-conductivity environments, it can be used in conjunction with void fraction / steam quality probes to estimate total fluid inventory, collapsed liquid level, and total coolant enthalpy.

EFP Series Probe Configurations

Inexpensive customized solutions

Our probe template library lets us give you inexpensive customized probe configurations for every application. Give us your application dimensions and characteristics of the media you need to measure, and we will produce a customized solution made specifically to fit your needs. Our engineers will help you pick the best options for your measurement application. All new probe designs undergo finite-element electromagnetic modeling to fine-tune signal processor response characteristics and ensure suitability to your task.

Liquid level

Numerous configurations: rigid coaxial, single or multi-segment; flexible flat (blade) probe, single or multi-segment.

Void fraction / steam quality

Numerous minimally-intrusive flat blade probe configurations or non-intrusive cross-channel designs are available. Self-seating probes for nuclear rod-bundle array installations are available.


Most applications can use either coaxial or blade probe configurations described for liquid level or void fraction / steam quality measurement. For unusual applications, specialized probes can be fabricated on a time and materials basis.


Multiple non-contact probe configurations customized for your application. These can be quite large, encompassing conveyor belts for process applications (e.g., process-line dryer applications), or can be made very small (e.g., moisture in thin tape or filament).

EFP Series Probe Materials

Stainless steel, all grades

The lowest cost probe, suitable for many applications. It can be made in any size and is easy to install and use.

Inconel® 600, 625, 690, 718

This probe material is used for long term applications in environments or solutions that may cause stress corrosion cracking in stainless steel.

Hastelloy® C276

This probe material is used for very long term applications at even more extreme conditions in which iron-based alloys would fail.

Zirconium 702

This material is used for high conductivity, high pH solutions and for situations in which a low cross-section for thermal neutrons is desired (e.g., nuclear reactor core rod-bundle installation). It is used with either the jacketed stainless or Inconel® cable. This is the most expensive of the probe/cable materials and requires special welding and fabrication techniques.

Ceramics and insulators

An important portion of any probe is the region where the probe is mated to the signal source. We have a number of special insulator materials for any situation, including specialized ceramics which allow probes and cables to sustain extreme environments for long periods of time.

EFP Series Cables

Stainless steel coax cable with copper-coated steel center conductor

Suitable for normal operating environments and basic probe design. This is the least expensive, and the best choice for many applications.

Stainless steel jacket with copper liner and copper center

This cable has a lower insertion loss and is good for high conductivity solutions or long cable runs. This is more expensive and difficult to fabricate and install.

Inconel® jacket with copper liner and copper center

This cable has the greatest temperature range and is the most durable option for long term applications in extreme enviroments or corrosive solutions that might cause stress corrosion cracking of stainless steel. This is a more expensive option but necessary for some high-temperature applications.

Cable lengths

Cables are chosen for ease of installation, environmental suitability, and signal characteristics and will vary depending on the application. Signal processors can be located more than 100 ft. (30 m) from probe installations with acceptable signal loss.

How to purchase

Every application is different, and our goal is to find the solution that fits your measurement and budgetary needs perfectly. An experienced application engineer is standing by to answer any questions and plan a customized measurement solution for you. Please contact us!