The Thomas Products LTD 1100 Series is a rugged, industrial-grade piston (shuttle) flow switch designed for reliable monitoring of liquid flow in demanding applications. Known as an industry standard, this in-line flow sensor offers exceptional durability, accuracy, and a wide range of customizable options to suit various media and environmental conditions. The device operates on a magnetic piston principle: a magnet-equipped shuttle is displaced by fluid flow, actuating a hermetically sealed SPDT reed switch when the factory-calibrated set point is reached.

Key Features

• High Pressure and Temperature Capability: The 1100 Series is engineered for extreme conditions. Standard brass/bronze units handle up to 400 PSI, while stainless steel versions can withstand pressures up to an industry-leading 5000 PSI at 100°F. Standard temperature ratings reach 300°F (150°C), with optional high-temperature models available up to 400°F (204°C).
• Clean-In-Place (CIP) Maintenance: The field-replaceable bonnet assembly allows for maintenance without removing the switch body from the pipeline. Simply depressurize the line, remove the nut, and pull out the bonnet assembly—reversing the process to restore operation. This design significantly reduces downtime and maintenance costs.
• Rugged, Globe-Shaped Body: The true globe-shaped one-piece cast body minimizes pressure drop and turbulence while maximizing pressure handling capabilities. Available in bronze, brass, or 316 stainless steel to meet diverse media compatibility requirements.
• Wide Flow Range and Customization: Factory calibrated set points are available from 0.5 to 100 GPM for water, with custom set points in water or oil upon request. Optional 100W SPST reed switches, relays for higher loads, and various electrical connections (including junction boxes and terminal strips) are available.
• Proven Reliability: The Model 1100 has passed rigorous testing for accelerated life, salt spray, shock, and vibration, ensuring long-term performance in harsh industrial environments.
• NEMA 4 Enclosure: The weather-tight enclosure provides protection against windblown dust and rain, splashing water, and hose-directed water, making it suitable for indoor and outdoor use.

Technical Specifications

• Switch Type: SPDT reed switch, 20VA pilot duty (optional 100W SPST).
• Electrical Connection: 24" 18 AWG polymer leads with 1/2" MNPT conduit connector (standard); optional MIS connector, various cables, and terminated ends available.
• Process Connections: 3/4" to 3" FNPT (standard). Optional port sizes: BSP, SAE, silver-braze, socket weld. Smaller pipe sizes can use appropriate bushings.
• Wetted Materials: Bronze, brass, 316 SST, ceramic ring magnet, PTFE, Viton.
• Accuracy: Set point accuracy ±10% max, repeatability 1% max deviation.
• Switch Differential: Approximately 10%.
• Response Time: Determined by media viscosity; consult factory for precise timing.
• Dimensions (Housing): 8" × 5" × 3".
• Weight: Approximately 1 lb (0.45 kg).
• Other Certifications: UL recognized (consult factory), silver precious metal contacts.

Installation and Maintenance

The 1100 Series is designed for in-line/pipe installation with horizontal port orientation recommended (leads up). For optimal performance, ensure proper pipe cleaning before installation. The Clean-In-Place feature allows for easy maintenance: depressurize the line, remove the nut, and extract the bonnet assembly. Reverse the process to restore operation. Optional silicone potting provides higher vibration resistance and repairability in case of failure.

Applications

The 1100 Series is ideal for flow/no-flow detection in a wide range of industries, including:

• HVAC systems (cooling towers, chillers, boilers)
• Machine tool industry (coolant and lubricant monitoring)
• Marine applications (engine cooling, bilge pumping)
• Chemical metering pump control (water treatment, residential well systems)
• Pump and bearing protection
• Oil and gas, power generation, and general industrial automation