Levalarms® Low Water Cut-Out and Level Switch Applications

Reliable Control of Alarms, Fuel Cut-Outs, Pumps

Install on boilers, Tanks Water Columns – Pressures to 1800 PSI (124 Bar)

Series EA-100: Single Function On Boilers Or Tanks

Actuate Electric Warning Signals or Fuel Cut-Out


Pressures to 800 PSI (53 Bar)


When tank or boiler levels reach predetermined high or low levels, the Levalarm will actuate bells, horns or lights.  EA-100 models are also used for fuel cut-out control.


Operation (Fig. 1) A stainless steel float swings at the end of a pivot rod.  The rod head carries an Alnico V magnet.  The magnet attracts one leg of a U-shaped armature which is attached to a miro-switch leaf actuator.  A buoyed float holds the switch open or closed, depending on terminals used.  As liquid levels fall, the float drops and direct the magnet to the opposite position.  A closed switch actuates alarms.  An open switch achieves fuel cut-out.


EA100D Shown Above (4 Bolt Flange) Rated at 350 PSI (24 Bar)


EA100S (6 Bolt Flange) Rated at 800 PSI (55 Bar)


Operation is highly reliable and sensitive because the magnet counterbalances the float, allowing accurate use of the float’s buoyancy.  Note that the magnet does not “slide,” thereby eliminating any friction that could impede movement and accuracy.


EA-101D & EA-101S: Dual Fuctions on Boilers and Tanks

Recommended Control For Power Plants and Processing Facilities.  Pressures up to 1800 PSI (124 Bar)

Pressure rating determined by probe selection (T probes = 450 PSI (30 Bar), V Probes = 1000 PSI (69 Bar), Z Probes = 1800 PSI (124 Bar))

compact design, versatile operation


levelarm ea101


Series EA-101 models provide reliable and instant response.  Probes respond to the rise and fall of water at predetermined points, to actuate a variety of controls.  Each Levalarm monitors up to 3-inch level variation.  Multiple units, in series, extend the monitoring range.  Use almost anywhere on boiler water applications.


One Probe/One Relay: High Alarm – Low Alarm – Fuel Cut-Out (Low Alarm & Fuel Cut-Out At Same Level).

Two Probes/One Relay: On And Off Pump Control Within 3-Inch Level Variation.

Two Probes/Two Relays: Dual Fuel Cut-Out (Low Alarm & Fuel Cut-Out On Different Levels).

Clark-Reliance Relays Improve Reliability, Offer Installation Ease and Economy

  • Each relay module is independently fuse protected.
  • Plug-in relays are removed by hand, no tools required.
  • Relays supply low voltage (12 VAC) to Probes.
  • Relays enhance sensitivity for extremely low water-conductivity applications, to 1 MicroMho.
  • Relays improve switch contact reliability for low load applications such as computer interface, recorders.
  • Relays use integral LED indicators to verify status.
  • Relays will retrofit existing system installations.

relay levalarm

Interwiring Diagram, Control Unit Relay

Typical Relay, Single Level Service

Direct Mode Operation (Standard)  When water level rises to Terminal 3 Probe, water completes circuit.  Circuit signals Relay to change state of load contacts, activating Alarm or other equipment, while illuminating integral LED.  Relay is energized until water drops below Probe to break circuit, turning off Alarm and LED.

Inverse Mode Operation (Optional) Upon powering Supply Terminals 1 and 2, Relay energizes (LED on).  When water rises to Terminal 3 Probe, Probe signals Relay to de-energize (LED off).  Relay remains de-energized until water drops below Probe.  Even during momentary power failures, Relay remains in “safe” mode in Low Level applications.  Specify inverse mode, when required.

Example Interwiring of Single Relay Control
Unit with Optional Vibratory (350N) and Holding Switch (HS-1) For Low Level Service

example interwiring


Fuel Cut-Out Probe Bypass

modle Hs1

During probe column or Levalarm blow-down, the Holding Switch provides a bypass around the fuel cut-out relay.  This simple switch maintains relay circuit continuity momentarily, while being held in the bypass position during blowdown.  The Holding Switch also provides an indicator light to verify that the fuel cut-out relay is functioning properly.  The switch can be installed to operate with probe-type Levalarms on boilers.  Also available without indicator light (Model HSO).

Audible, Visual Alarms

visual alarms

Audible or visual alarms are available for all Levalarm applications.  The vibratory horn has a decibel rating of 100 DB at 10ft. and comes in standard model (350N) or weatherproof model (350W).  Visual alarms come in Normal/Danger and High/Normal/Low models.  Specify supply voltage, when ordering.

levalarm models

(*) Add “W” suffix to model for socket-weld connections



Brochure: Prismatic (Reflex) Water Gages 

Order Selection Worksheet: R406.004 Prismatic (Reflex) Water Gages

Drawings: C & S Type Prismatic (Reflex) Water Gages

IOM: Prismatic (Reflex) Water Gages