Fluid sensors and accessories

Eaton’s portfolio of fluid-sensing and condition-monitoring technologies help optimize engine health and include liquid level indicators, sight gauges, online lube debris monitoring and other highly reliable products and accessories.

For sales or a quote, please contact our authorized distributor Herber Aircraft


Phone: 1-310-322-9575
Toll-free: 1-800-544-0050 

Direct contact:
David Becker
Phone: 310- 322-9575 ext 210 
Email: dbecker@herberaircraft.com


Snap action fill caps

Our single-piece, spring-activated filler caps are designed for reservoirs, oil tanks and gearboxes. Their novel single-piece aluminum construction permits one-handed operation with no danger of dropping or damaging the cap itself. Spring activators may be alternately used for stay-open or auto-close operation.


  • Filler cap assembly uses standardized modular approach 
  • Three basic sizes comprise five coupling styles to maximize design flexibility
  • Configuration options include long hinge pin (so cap cannot remain open), a lockband feature, or one of three special breathing elements
  • Three standard filler sizes are snap cap “building blocks”; each unit may be used alone or have standard/special mount adapters added

Standard adapters

Our standard modular line includes five adapters that are suitable for most general applications. We also design unique mounting arrangements to suit our customers’ applications. Please contact Eaton for details. 

Liquid level indicators

Sight gauges are an economical method to monitor fluid levels in reservoirs, tanks, gear cases and machinery. Eaton’s product offering includes polymer-sealed and fused-glass (pipe and SAE threaded) models. See below for more information.

Types and features:

  • Polymer-sealed
  • Sight plugs / Oil eyes: Standard and custom threaded plug style sight plugs. 
  • Prismalites: Custom devices providing rugged, reliable monitoring of machine fluids in unique situations. Normally installed for top viewing of oil, hydraulic fluid or coolant levels but equally effective as bottom or side-viewing sight gauges. Typically used to obtain rapid and accurate FULL or LOW indication depending on whether fluid is PRESENT or NOT PRESENT at the prismatic cone.
  • High-contrast sight plugs and gauges: Pipe-thread sight plugs use a steel body with corrosion-resistant finish. Straight thread models use an aluminum alloy body and are designed to take an O-ring seal. Plug materials include aluminum alloy body, borosilicate lens and gaskets compatible with hydraulic and lubricating fluids at temps up to +350°F (+177°C).
  • Flow-through indicators and special devices: Line-of-sight flow indicators are capable of high pressures and high temperatures. In-line windows allow observation of liquid movement, contamination or discoloration. Pressure ratings are 500-4,000 psi at operating temps to +250°F (+121°C). 
  • Spanner wrench sight windows: These gauges are recommended for MS port installations or where conventional installation is not practical. Units can include stainless steel reflector.

Flush mount sight gauges

Eaton offers a variety of flush-mount designs that provide clear, accurate liquid-level indications. 

Types and features 

  • High-contrast gauges: Provide superior legibility of fluid level regardless of fluid color or transparency. Standard materials include aluminum alloy housing, borosilicate lens and Fluorocarbon gasket. Most gasket materials also available as a special-order option. Standard operating conditions are 15 psi at +350°F (+177°C). Contact Eaton for higher temp and pressure applications. 
  • “See Level” sight gauges: Designed for direct observation of actual liquid level. Three available sizes of plastic domes offer the most cost-effective solution for level-indicating requirements. Standard materials include die-cast aluminum housing, acrylic plastic sight dome, Buna-N gasket and aluminum alloy reflector. Maximum temp and pressure are +180°F (+82°C) at 5 psi. Other temperature and pressure ranges can be accommodated. Contact Eaton for more information. 

Fused glass models (pipe)

Eaton’s economical, high-strength units are fabricated from a carbon steel housing and a thick section of high-strength glass. A pressure-tight seal is formed by compression on the glass perimeter, thus eliminating elastomers.

Our fused assembly can withstand high-temperature and high-pressure environments. It also can accommodate special chemical compatibility requirements by a simple change of plating. Standard units are stocked with electroless nickel finish.


Eaton’s breather vents permit free exchange of filtered air for gear cases vented to atmosphere. 


  • Rugged, corrosion-resistant, all-metal construction
  • Basic model types pass air through a filter media to stop solid particles
  • Wide range of standard designs available in addition to custom filter and check valve units
Eaton Breather Vent

Breather plugs

The most commonly used sizes are listed. To order a micro filter breather, add suffix “MF” (e.g., M810MF). Type 1 breathers are available with splash-proof cover; add suffix “V” (e.g., M810V). Breathers also are available with stainless steel bodies.

Check valves

Model M828K employs a M828 breather body and adds a rugged, reliable, unidirectional check valve that opens at 1-4 psi.

Any of the breather housings shown may be converted to a check valve in short order.

Chip collectors

Magnetic chip collection is the most economical and direct form of lube system failure detection in use today and works by capturing wear-generated debris in transmissions and gearboxes. Usually located in a gearbox or reservoir drain plug, the collector captures and retains particles for later removal and off-line analysis. 


  • Easy to install 
  • Facilitates periodic inspection for failure or early wear 
  • For new designs or retrofit onto existing systems 
  • Unique self-closing valve prevents oil loss when removed 
  • Available in a wide variety of thread sizes and diameters 
  • Available with special drain-line adapter for convenient no-spill lubricant drainage 
Eaton chip collector

Chip detectors

We developed the chip detector (an electrical version of our chip collector) for helicopter gearbox use to provide an electrical signal when it detects lube system debris. Sensors found in nearly every aviation application were adapted for critical industrial applications such as gas turbines, transmissions, compressors and gearboxes.


  • Easy to install 
  • Facilitates remote signal for failure or early wear detection
  • For new designs or retrofit onto existing systems 
  • Unique self-closing valve prevents oil loss when removed 
  • Available in a wide variety of thread sizes and diameters 
  • Available with special drain-line adapter for convenient no-spill lubricant drainage 

Electro-optic and liquid level sensors

LevelPro sensors are the ideal choice for process control, beverage, fuel, lube, coolant, hydraulic and other liquid level detection challenges.


  • Simple, rugged, reliable
  • Solid-state, electro-optic liquid detectors with no moving parts
  • Wide range of standard design options available