TWR - Temperature Switch for Liquids

The KOBOLD TWR is a liquid temperature switch that provides factory-set thermal switching for liquids in pipe systems and tanks. This bi-metal switch operates at a preset switch point to deliver temperature alarm functions or, when two units are paired, wide-hysteresis (deadband) thermostatic control of heating and cooling equipment. It is available in nickel-plated brass or 304 stainless steel with a 3/4" NPT process fitting.

How the TWR Liquid Temperature Switch Works

The TWR uses a bi-metal sensing element that reacts to liquid temperature and actuates its contacts at a factory-set switch point. A single unit provides high or low temperature alarm functions designed to support process compliance with maximum or minimum limits. Two units paired together provide wide-hysteresis thermostatic control of heating and cooling systems.

Switch Points and Accuracy

Switch points are factory-set across twelve fixed steps from 86°F to 248°F (30°C to 120°C). Values rise in 9°F increments between 86°F and 122°F, then in 18°F increments between 122°F and 248°F. Switching accuracy is ±9...13°F (±5...7°C) and hysteresis is a maximum of 36°F (20°C).

• 86°F, 95°F, 104°F, 113°F, 122°F
• 140°F, 158°F, 176°F, 194°F, 212°F, 230°F, 248°F

Materials and Process Connection

The TWR is offered with wetted parts in nickel-plated brass or 304 (1.4301) stainless steel to suit the process liquid. It installs directly into pipes or tanks through a 3/4" NPT fitting. The housing is rated IP 65 and measures 2.95" high, or 3.23" high with a signal lamp, with a 1.38" hex.

Pressure and Temperature Ratings

The TWR is rated for a maximum process pressure of 928 PSIG (64 bar) and a maximum media temperature of 248°F (120°C). Ambient operating temperature ranges from -22°F to 257°F (-30°C to 125°C). Operation outside these limits can damage the unit.

Electrical Connection and Contact Options

Electrical connection is made through a DIN 43 650 plug, with contacts available as normally open (N/O) or normally closed (N/C). The plug is optionally available with an integrated signal lamp for visual indication of switch condition. Contact ratings depend on the lamp option:

• Without signal lamp: 250 VAC or 30 VDC, 4 A; switching current 0.1...4 A
• LED option (24 VDC lamp): 30 VDC, 1 A; switching current 0.1...1 A
• GLP option (110 VAC lamp): 125 VAC, 1 A; switching current 0.1...1 A

Installation Guidelines

Install the switch with a proper thread sealant, avoid overtightening it in the fitting, and check for leaks before start-up. The sensing bulb must be fully immersed in the liquid being monitored, because an air pocket around the bulb causes slow response or switch malfunction.

• In horizontal pipe, do not mount at the top (12 o'clock position), where trapped air can insulate the bulb.
• In horizontal pipe, do not mount at the bottom (6 o'clock position), where sediment can settle on the bulb.
• Keep the coupling short enough for the bulb to extend past the pipe or tank wall into the liquid, so it does not read a stagnant pocket.

The TWR is made in the USA.

Important Notice: Transitioning to U.S. Manufacturing

Due to the ongoing implementation of EU Directive 2020/2184 that restricts brass materials, product availability is subject to change at any time. We are actively reshoring production of our brass flowmeter models to U.S. facilities to ensure continued supply. Not all products can/will be reshored. During this transition, stock availability may fluctuate between the time of quotation and purchase order placement. We appreciate your patience as we work to establish our domestic supply chain and remain committed to providing you with the same high-quality products made closer to home.

Common Questions about TWR - Temperature Switch for Liquids