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TWIP® Level Switches
(Turbine Water Induction Protection)

for Alarms, Trips, Drain Pot, Heaters, Deaerators, and Condensate Tank Applications

TWIP® System Detection Protects Turbines and Other Equipment Applications 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.

twip level switch

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.

As an option, two trip probes can be installed vertically 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.

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.

The Water Detector - where the TWIP System’s liquid connections end – and advanced electronic operation begins.

The Water Detector is attached to steam plant equipment or piping. To facilitate installation, connections may be of 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 (206 Bar) or temperatures to 1100°F (593°C).

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.

Traditional & Brazed Probes


The performance reliability of the TWIP System is related directly to the exceptional success of Clark-Reliance Probes. Clark-Reliance pioneered Probe technology and now continues to lead in the innovative design and precision manufacture of water detecting Probes.


Located in the Water Detector, the 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.

Control Unit

Contains plug-in electronic relays which respond to probe contact with water, automatically activating alarms or controls.

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 deactivation 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.

Water Level Indicator (Optional)

Miniature indicators can alert personnel to presence of water.

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.

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.


traditional and brazed probes
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