Thermal Differential Flow Switches

      Thermal Differential Switches use a thermal differential technique to measure liquid flow, level or interface by sensing changes in the thermal heat transfer characteristics of the media where it is located. The sensor consists of a pair of matched Resistance Temperature Detectors (RTDs) encased in twin 316 series stainless steel tubes. One RTD is self heated using a constant DC current.

      The other sensor is unheated and provides an accurate ambient process temperature reference. The thermal differential created between the heated and reference RTD pair is a function only of the media with which the sensor is in contact. The differential is greatest when no liquid is present (dry condition) and decreases as liquid quenches the switch sensors (wet condition).

      • Wide operating process temperature range of -100 to 392°F
      • Removable, plug-in electronics board
      • Free of all moving parts that can stick, coat or fail
      • Self-heating sensor design
      • Application flexibility
      • Simplifies wiring
      • High reliability
      • Improves response time and sensor durability

      Thermal Differential Flow Switch

      Thermal Differential Flow Switch

      Models: T21
      Ranges: -100° to 392°F, -70° to 200°C
      Certifications: Unit: CRN, CSA, RTN
      Warranty: 1 Year

      The model T21 point flow switch uses a thermal differential technique to measure liquid or gas flow, level or interface by sensing changes in the thermal heat transfer characteristics of the media where it is located. The sensor consists of a pair of matched Resistance Temperature Detectors (RTDs) encased in twin 316 series stainless steel tubes. One RTD is self-heated by a constant DC current while the other is unheated, in contact with the liquid and provides an accurate ambient process temperature. It is adjustable to a specific flow rate.

      The T21 is a popular choice for low-flow alarm switching, monitoring lube oil on bearings and gears in rolling mills and monitoring the flow of cooling water on pump seals.

      • Wide operating process flow ranges of -100°F to 392°F
      • Removable, plug-in electronics board
      • Self-heating sensor design

      Datasheet

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      Certifying Agencies

      ATEX (certified by Baseefa, DEMKO, or KEMA)

      CE

      CSA

      FM

      GOST

      IECEx (certified by Baseefa or Standards Australia)

      INMETRO

      PESO (CCOE – India)

      TIIS

      KOSHA

      Rostechnadzor (RTN)

      SIL, TestSafe (SAA – Australia)

      SASO

      UL

      Available Listings

      Ordinary Locations and Hazardous Locations
      SIL Level Switch Certificate
      SIL Pressure Switch Certificate

      Available Hazardous Locations Protection Methods

      Explosion Proof/Flameproof (d)
      Intrinsic Safety (ia)
      Encapsulation (m)
      Special Protection (s)
      Combustible Dust (tD)
      Energy Limited (nL)

      Division 1, Division 2
      Class I, Class II, Class III
      Groups A-G

      IECEX
      saso
      INMETRO
      kosha
      gost
      PESO
      Testsafe
      atex-certification
      FM-Approval
      ul certification
      TIIS
      csa