TWIP® Level Switches for Alarms, Trips, Drain Pot, Heaters, Deaerators, and Condensate Tank Applications

Turbine Water Induction Protection System

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.

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

water detector


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




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.



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