Levalarm® & TWIP® Level Switches

Pressures up to 3000 PSI (200 Bar) • Low Water Cut-Outs • Level Alarms & 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






Turbine Water Induction Protection System

twip figure 1


TWIP® System Detection Protects Turbines From Catastrophic Damage Caused By Water Influx 

The most effective protection against turbine water damage is a well designed steam plant.  However, in the best of plants, the potential for disaster remains ever present.  Industry research indicates a 35% probability of new equipment damage during the first five years of operation. Abnormal conditions can arise quickly.  Pump failures, valve failures, excessive condensation, site flooding and other events make every steam plant a possible candidate for swift and unexpected turbine damage.


Designing For Accuracy 
The ideal water detection device must fulfill multiple objectives.  Foremost, false alarms are unacceptable.  Equally undesired are the cost and nuisance of routine testing to assure proper equipment performance. The TWIP System attacks these detection problems directly and effectively.  TWIP combines industry’s most successful sensing Probes with a choice of versatile, high technology equipment options.  TWIP systems of proven reliability and accuracy are easily tailored for strategic location within any individual steam plant. The utmost in performance is achieved in TWIP Systems using the optional “Voting Logic” trip circuit – employing a circuit logic in which any 2 of 3 designated probes will activate the trip circuit when water is present.  Voting Logic virtually eliminates false trip Probes – or a single level control failure. As an option, two trip Probes can be installed in the Water Detector at the same level (trip point), to assure that even with voting logic circuitry, the trip point is always at the same single level.

voting logic

Typical Power Plant Installation Locations

Drain Pots • Deaerators • Flash Tanks • Feed Water Heaters • Boiler Drums • Water Columns • Storage Tanks • Separators • System Piping • Wherever Water Presence Must Be Known



Water Detector


control unit


water detectorconnection options



Performing as a small, independent chamber, the Water Detector is attached to steam plant equipment or piping. To facilitate installation, connections may be the size, type and orientation best suited to each application.  The Water Detector is available in various materials to withstand system pressures to 3000 PSI (200 Bar)and temperatures to 1100°F. One or more sensing Probes are located at various chamber levels to signal the arrival or level of water within.  Probes may be installed at whatever chamber locations are desired. The Water Detector is where the TWIP system’s liquid connections end – and advanced electronic operation begins.


Optional FLEXPAK® Jacket

For maximum system accuracy and personnel safety, the Water Detector should be insulated with the optional FLEXPAK jacket.  The jacket provides a 2-inch thick insulation that is easily removed for routine equipment inspections.  The jacket is suitable for outdoor service.


traditional probes
brazed probes


The performance reliability of the TWIP system is related directly to the exceptional success of Clark-Reliance Probes.  Clark-Reliance pioneered Probes technology and now continues to lead in the innovative design and precision manufacture of water detecting Probes. Located in the Water Detector, or acting as individual units in piping, sensing Probes complete an electrical circuit when water reaches the Probe tip.  The completed circuit signals a relay in the Control Unit which, in turn, can activate an alarm, drain, pump or other equipment. Clark-Reliance Probes allow even pure water of ultra-low conductivity (less than 1 micro mho) to complete electrical circuits. ZG and FG Probe service life is extended with low cost Probe Repair Kits.  Kits allow field replacement of components subject to normal wear factors.

twip system probes


control unit 1



TWIP Control Units, employing plug-in relays, printed circuit boards and other advanced componentry, are lightweight, compact and easily installed.  Control Units may be located up to 1000 feet from the Water Detector. In “direct mode” operation, water that contacts any sensing Probe immediately completes an electrical circuit to the Probe’s corresponding relay in the Control Unit.  The relay activates auxiliary functions such as indicators, solenoid valves, drain valves, audio/visual alarms, or other protective devices programmed to counteract or respond to the detection of unwanted water. Relays may also work in an “inverse” mode, providing de-activation of electrical controls to prevent false signals during a power outage. When water drops below the sensing Probe, the corresponding relay will revert to its prior state.  Relays supply 12 VAC to Probes and require 115 VAC or 230 VAC 50/60 Hz line supply.  Time delay is available upon request.  Each control relay contains an LED to verify operational status.






Optional Dual Power Supply Diverter

dual power supply

TWIP Control Units can be wired to operate from two power sources.  Operation can switch automatically between power sources A and B in the event of outages.


water level alarm

twip indicator table


TWIP Indicators employ panels of lights to show the presence of water – in a Water Detector chamber or at the location of a sensing Probe installed in plant piping.  The Indicator may also be employed to show that a TWIP system relay has been activated. Requiring only electrical connections, one or more Indicators may be quickly and easily installed in control rooms or other key locations throughout the plant. Indicators use light emitting diodes (LEDs) which normally provide more than 10 years of service.  LEDs are red or green.



  • TWIP Systems include the Water Detector, Water Detector Housing, Probe(s), Control Unit.
  • Major options include the TWIP Indicators, Dual Power Supply Diverter, FLEXPAK Jacket, choice of NEMA Control Unit Enclosure, Integral Junction Box, plus electrical specifications as required.
  • Water Detectors and Probes are available for pressures 3000 PSI (200 Bar) and temperatures to 1100°F.  Water Detectors comply with ANSI B31.1 on request.
  • Each Probe comes with a 30″ high temperature lead.  Use of 18 AWG silicone insulated wire is recommended for TWIP system on-site wiring.
  • Relays are furnished for line voltage and frequency as specified.  Switch contacts are UL rated at 5A/115 VAC, 8A/230 VAC and 1A/125VDC.






TWIP figure 1 and 2



Brochure: TWIP® System

Order Selection Worksheet: TWIP System

Drawing: Refer to Order Selection Sheet for Column Data

Relay Control Units 

IOMs: TWIP System