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Thermatel® TD1/TD2 Thermal Dispersion Switches

Brand: Magnetrol

The Thermatel® Model TD1/TD2 switch is utilized in flow, level and interface applications.

The TD1/TD2 is popular for pump protection, specifically low flow detection with the unique spherical tip design, to prevent pumps from running dry.

Continuous diagnostics with fault indication, temperature compensation and fast response time make the TD1/TD2 the latest in thermal dispersion technology.

Technology - Thermal Dispersion Switch

The thermal switches are based on convective heat transfer.  One sensor is at the process temperature and the other is being heated by a constant power.

As the flow rate increases, the temperature difference between the sensors decreases.  A set point is established so when that specific temperature difference is reached the relay changes state.

This can be on either increasing or decreasing flow or flow/no flow.  When used in a level or interface application it is primarily the thermal conductivity of the fluid that will provide the difference in heat transfer.

Operating Principle

The THERMATEL sensor consists of two RTD elements. One is the reference and the second is heated to a temperature above the process temperature.

The electronics detect the temperature difference between the two elements. The temperature difference is greatest in air, then decreases when cooling occurs due to a change in media.

An increase in the flow rate further decreases the temperature difference.

The set point is adjusted for the switch to alarm at the desired temperature difference. Once the set point is reached, the relay will change state.
Features
  • Temperature compensated to provide repeatable alarm under varying process temperatures
  • Continuous diagnostics detect sensor fault
  • Non-linear mA output signal can be used for trending, diagnostics and repeatable flow/level indication
  • Detects minimum flow or presence / absence of flow
  • Excellent low flow sensitivity
  • Simple calibration / installation
  • Options:
    • Hot tap retractable probe
    • Hygienic design
    • NACE construction
    • Window to view alarm status
    • Integral or remote electronics
    • Flow body for very low flow detection

Specifications

Brand

Approvals

  • ATEX Ex d, Ex d+ib
  • CCOE Ex d
  • CSA XP, NI
  • FM XP, NI
  • EAC (GOST) Ex d
  • IEC Ex d, Ex d+ib
  • INMETRO Ex d, Ex d+ib
  • Korea Ex d
  • SIL 1

Supply Voltage

  • TD1: 19.2 to 28.8 Vdc
  • TD2: 19.2 to 28.8 Vdc or 100 to 264 Vac, 50/60 Hz

Power Consumption

  • TD1: 3.5 Watts at 24 Vdc, 4.5 Watts at 28.8 Vdc
  • TD2: 4 Watts at 24 Vdc, 4.5 Watts at 28.8 Vdc, 5 Watts at 100 to 264 Vac

Power to Probe

  • Less than 1 Watt

Output Relay (Gold Flashed)

  • TD1: DPDT, 8 amp at 120 Vac, 250 Vac, 8 amp at 28.8 Vdc, 0.5 amp at 125 Vdc
  • TD2: DPDT, 8 amp at 120 Vac, 250 Vac, 8 amp at 28.8 Vdc, 0.5 amp at 125 Vdc or Hermetically Sealed DPDT 1 amp at 28 Vdc, 0.2 amp at 125 Vdc

Ambient Temperature

  • Electronics: -40° to +158° F (-40° to +70° C)

Storage Temperature

  • Electronics: -58° to +170° F (-50° to +76° C)

Operating Temperature

  • Sensor: -100° to +400° F (-73° to +204° C)➀
  • ➀Use a Probe with Heat Extension or Remote Electronics for Process Temperatures Greater than +250° F (+120° C)
  • High Temperature Sensor: -100° to +850° F (-73° to +454° C)

Response Time

  • 1-10 seconds (Typical - Dependent upon Sensor Type, Application, and Set Point Adjustment)

Set Point Range

  • Water: 0.01 to 5.0 FPS (0.003 to 1.5 m/s) (Spherical Tip and Twin Tip Sensors) | 0.01 to 1.0 FPS (0.003 to 0.3 m/s) (HTHP, Hastelloy, Monel Sensors)
  • Air: 0.1 to 500 SFPS (0.03 to 150 Nm/s)

Time Delay (TD2 only)

  • 0-100 seconds Adjustable (Time Delay in Addition to Sensor Response)

Repeatability

  • < 1 % at Constant Temperature

Enclosure Material

  • Cast Aluminum A356 Containing Less than 0.2 % Copper
  • 316 Stainless Steel or 304 Stainless Steel

SIL

  • Safe Failure Fraction (SFF) TD1=69.3 % TD2=73 %

Probe Materials of Construction

  • Twin Tip: All Wetted Parts of 316/316L Stainless Steel, Hastelloy C, or Monel
  • HTHP Sensor: 316/316L Stainless Steel, Hastelloy C
  • Mini Sensor: 316/316L Stainless Steel
  • Spherical Tip: 316/316L Stainless Steel
  • Low Flow Body: 316/316L Stainless Steel

Probe Insertion Length: Spherical Tip Probe, TXA, TXB, Twin Tip Probe, TXC, TXD

  • Available in Lengths from 2 to 130” in 1” increments (5 to 330 cm in 1 cm increments)

Mini Sensor, TXM

  • Available Insertion Lengths 1 to 130” (3 to 330 cm)

High Temperature Sensor, TXH

  • Available in Lengths from 2 to 36” in 1” increments (5 to 91 cm in 1 cm increments), Consult Factory for Longer Length

Low Flow Body, TEL

  • 1/4” and 1/2” NPT and G (BSP) Threads

Cable Length

  • 500 feet (150 meters) Max.

  • Chemical
    • Chemical Injection
    • Chemical Injection Skids
    • Chemical Reactors
    • Chlor-Alkali Process
    • Deionization Tanks
    • Liquid-Liquid Extraction
    • Mixing & Blending Systems
    • Neutralization
    • Tank Blanketing
  • Common Applications
    • Flow: Air Flow
    • Flow: Centrifugal Pump Protection
    • Flow: Compressors & Pumps
    • Flow: Gas Mixtures Flow
    • Flow: Liquified Gases
    • Flow: Single Gas Flow
    • Level: Containment & Drainage Sumps
    • Level: Lubrication Oils & Hydraulic Fluids
    • Level: Process & Field Storage Tanks
    • Level: Water Storage & Wash Tanks
  • Crude Oil
    • Crude Dehydration
    • Crude Desalting
    • Production Fluid Storage
    • Tank Blanketing
    • Vapor Recovery Unit
    • Wellstream Separation
  • Hydroelectric Generation
    • Oil/Water Interface Detection
    • Oil & Hydraulic Fluid Reservoirs
    • Pump Protection & Cooling Water Flow
  • Natural Gas
    • Chemical Injection Skids
    • Compressor Scrubber
    • Compressor Waste Liquid
    • Flare Knock-out Drum
    • Gas Dehydration
    • NGL Recovery & Storage
    • Separators
    • Sour Gas Treatment
    • Sulfur Recovery
    • Vapor Recovery Unit
  • Nuclear Power
    • Cooling Tower Basins
    • Cooling Tower Intake & Basin Levels
  • Petroleum Refining
    • Blending Operations
    • Crude Desalting
    • Refinery Flow Applications
  • Power Generation
    • Condensate Receiver Tanks
    • Cooling Tower Basins
    • Cooling Tower Intake & Basin Levels
    • Deionization Tanks
  • Pulp & Paper
    • Black, Green & White Liquor
    • Condensate Receiver Tanks
    • Digester Blow Tanks
    • MC Pump Standpipes
    • Mixing & Machine Chests
    • Pulp Bleaching Towers
    • Pulp Digesters
    • Pulp Storage
    • Pulp Washing Systems
    • Turpentine Recovery
  • Renewable Energy
    • Biogas
    • Geothermal
    • Hydroelectric
    • Solar
    • Wind
  • Water & Wastewater
    • Blower Air Flow
    • Carbon Slurry Level
    • Digester Gas Flow
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