Thermal Switches

New hot-swap switch offers thermal ‘peace of mind’ to sudden overvoltage, undervoltage, and overcurrent conditions.

Hot spots at varying locations on a PCB (printed-circuit board) present a difficult scenario for an effective thermal-management to lessen the risk of meltdown or fire. A hot-swap switch with carefully placed temperature sensors might be the answer. The thermal switch would offer protection by forcing the hot-swap controller to instantly disconnect system power once the ambient temperature exceeds the preset level. For multiple hot spots, multiple temperature switches would have to be used.
Inexpensive temperature sensors and hot-swap controller, writes Donald Schelle in Electronics, Design Strategy News, can reduce the cost of this circuit to approximately $2 in low-volume applications.

Best-in-Class Thermal Switches provide:

• Flow Switch for gas, liquid and slurries
• Liquid Level Indicator Switch
• Single pot sets switch point
• All welded sensor construction

Top Considerations before Buying Thermal Switches :

Offers a rugged yet economical flow and level switch for gas, liquid and slurry applications, and also made of robust construction capable of use in hazardous environments. It is FM and CE approved and there are no moving parts.

Key Products:

1. Fluid Components International, founded in 1964, is engaged in the design and manufacture of flow, level, and temperature instrumentation employing thermal dispersion technology. The company's products provide solutions for industrial process and plant applications using both patented thermal dispersion and Coriolis flow measurement technologies.  The product line includes air, gas and liquid flow meters, flow switches, level switches, and flow conditioners. In 1978, the company qualified the first thermal flow switch to meet IEEE 323 and 344 requirements for Safety-Related nuclear application, and continues to supply both existing and newly constructed nuclear plants with flow and level switches, thermal mass flowmeters, continuous level transmitters, and temperature switches. I n order to ensure industry-best, installed calibration and performance, the company also offers an on-site, NIST-traceable, flow calibration laboratory that performs gas calibrations in a customer's actual process conditions.

2. Kurz Instruments, founded in 1977 by Jerry Kurz, began operations specializing in thermal flowmeters that measured particle size and distribution in the air, worked like hot-wire anemometers, but were ruggedized and hardened to fit into more demanding industrial environments. Today, Kurz Instruments still engineers and develops products for flow, level, and interface applications designed to operate in the harshest of environments, including combustion air, aeration air flow, digester gas, nuclear power plants, pump protection, flare stack monitoring and compressed air. Kurz Instruments is especially active in the power industry. Kurz has developed a series of single-point and multipoint insertion thermal flowmeters for stack-gas and flare-gas monitoring. Kurz’s flowmeters are also used in the refining, cement, pulp and paper, and other process industries. The Kurz product line includes flow process sensors, industrial temperature sensors, velocity sensors, flow transmitters, mass flow transmitters, control valves, solid flow sensors, flow totalizers, velocity meters, air flow measuring instrumentation, air measurement instruments, flow measurement computer systems, flow indicators, flowmeters, air flowmeters, mass flowmeters, and thermal mass flowmeters.

3. Eldridge Products, Inc., founded in 1988 by Mark Eldridge, who formerly worked for the well-known, thermal flowmeters specialist company Kurz Instruments (Kurz begun by Jerry Kurz in 1977), specializes in thermal flowmeters for gas sub-metering, compressed-air monitoring, and water and wastewater treatment. Today, the company is engaged in the development and manufacture of custom measurement and control systems, including thermal gas mass flow meters, switches, flow averaging tubes and sensors. Types of flow meters include inline and insertion flow meters with integral and remote electronics. Flowmeters meet CE, CSA/CUS & ATEX standards. Multipoint systems are also available, such as multipoint systems including probes, control panels and adapters. Applications include compressed air, natural gas consumption, combustion flow of air and natural gas, stack flow, automotive, food processing, drying air, petroleum plants, municipal waste, semiconductor, chemical processing, cogeneration, and power plants. Process gas, maximum flow rate, gas temperature and pressure, line size, input power, enclosure rating, electronics and mounting styles, sensor option and mounting hardware.

4. Fox Thermal Instruments, Inc. was founded in 1994 by Brad Lesko, another former employee of Kurz Instruments to leave Kurz and begin operations. The company specializes in thermal flowmeters for compressed-air monitoring, emissions monitoring, and fuel monitoring applications. The company is also engaged in the development of flow instrumentation and expertise for solutions to industrial greenhouse gas (GHG) emission rule (40 CFR Pt. 98). Examples include inert and explosive gases, as well as mixed and corrosive gases. By utilizing rugged stainless steel or Hastelloy flow meter designs, Fox Thermal Instruments flow meters deliver both inline and insertion flow metering. The air flow and gas flow meters are designed to be usable in a wide variety of applications, including inert and explosive gases, as well as mixed and corrosive gases. In addition, Fox delivers both inline and insertion flow meter model.

Thermal Switch
Definition: A thermal switch (sometimes referred to as a thermal reset) is a device which normally opens at a high temperature (often with a faint "plink" sound) and re-closes when the temperature drops. The thermal switch itself is a bimetallic strip, often encased in a tubular glass bulb to protect it from dust or short circuit.