Double Throw (DT) Velocity Flow Switches
Last Updated: April 1, 2025
Description
Double Throw (DT) Velocity Flow Switches are devices designed to monitor the flow of liquids or gases within a system. They operate by detecting changes in flow velocity and can switch between two states, providing a signal to control systems or alarms based on the flow conditions.
Working Principle
DT Velocity Flow Switches typically utilize thermal dispersion technology, which involves two resistance temperature detectors (RTDs). One RTD is heated while the other measures the process temperature. The difference in temperature between the two RTDs is used to determine the flow rate. As the flow increases, the cooling effect on the heated RTD increases, reducing the temperature difference. This principle allows the switch to accurately detect flow changes and trigger the appropriate response. These switches are useful because they provide reliable monitoring of flow conditions without moving parts, reducing maintenance needs and increasing durability.
Applications
DT Velocity Flow Switches are commonly used in various industrial applications. For example, they are employed in natural gas fractionation facilities to monitor relief valve leaks and ensure system safety . They are also used in refinery cooling systems and chemical plants to protect pumps from failures by monitoring flow conditions and triggering shutdowns if necessary .
Advantages over other Materials - Plastics and Polymers
While specific advantages over plastics and polymers are not detailed in the provided documents, it is generally known that metal-based flow switches, such as those made from stainless steel, offer superior durability and resistance to harsh environmental conditions compared to plastic or polymer-based switches. This makes them more suitable for industrial applications where high temperatures, pressures, or corrosive substances are present.
Limitations
One limitation of DT Velocity Flow Switches, particularly those using electromechanical components, is their limited contact life cycle and slower response time compared to solid-state switches . Additionally, the initial cost of these switches can be higher due to the complexity of their design and materials used.
Considerations
When selecting DT Velocity Flow Switches, several factors should be considered. Initial costs can be significant, especially for high-quality, durable models. Operating expenses are generally low due to the lack of moving parts, which reduces maintenance needs. However, the accuracy and repeatability of the switch are crucial, especially in applications where precise flow monitoring is essential. Replacement and maintenance costs are minimized due to the robust design and long mean time between failures (MTBF) of up to 190 years for thermal flow switches .
from Sierra Instruments, Inc.
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- Throws: Double Throw
- Mounting: Insertion
- Meter Technology: Thermal
- End Fittings: In-line Threaded
from Fluid Components Intl. (FCI)
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- Mounting: Insertion
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- End Fittings: In-line Flanged
from Fluid Components Intl. (FCI)
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- Mounting: Insertion
from KOBOLD Instruments, Inc.
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- Throws: Double Throw
- Mounting: Insertion
- Meter Technology: Paddlewheel
- End Fittings: In-line Flanged
from OMEGA Engineering, Inc.
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- Throws: Double Throw
- Mounting: Insertion
- Pipe Diameter: 1.00 to 10.00
- End Fittings: In-line Threaded
from Shanghai Yuanben Magnetoelectric Tech. Co., Ltd.
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- Throws: Double Throw
- End Fittings: In-line Threaded
- Meter Technology: Paddlewheel
- Process Media Type: Liquid; Gas
from Sitron
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- Throws: Double Throw
- Mounting: Insertion
- Pipe Diameter: 0.50 to 2.00
- End Fittings: In-line Flanged; In-line Threaded
from KOBOLD Instruments, Inc.
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- Throws: Double Throw
- Mounting: In-line
- Pipe Diameter: 0.50 to 0.75
- End Fittings: In-line Threaded
from Sitron
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- Throws: Double Throw
- Mounting: Insertion
- Pipe Diameter: 0.50 to 2.00
- End Fittings: In-line Flanged; In-line Threaded