Flow Switch Keeps It Clean In Sanitary Processes

Feb. 25, 2021

Design, process, and plant engineers responsible for maintaining a sanitary environment in pharmaceutical, biotechnology, and food/beverage plants will find that the FLT93C Flow Switch provides accurate liquid flow rate measurement for clean in place (CIP) system operational integrity.


With its stainless steel wetted materials and standard 20Ra finish, available in either mechanical polish or electro-polish finishing, the sanitary flow switch supports both skid-mount and stationary clean-in-place (CIP) systems. The primary purpose of these systems is to ensure all process piping and equipment are thoroughly cleaned per ASME BPE standards.


The FLT93C Flow Switch monitors the process cleaning solution’s minimum liquid flow rate to ensure it is maintained during the entire cleaning process runtime. Operating over a wide liquid flow range of 0.01 to 3.0 fps (0.003 to 0.9 mps), the flow switch offers accuracy of ± 0.5% reading or ± 0.04 fps (± 0.012 mps).


Designed with unique temperature compensation technology, the switch ensures set point accuracy for process temperatures that can vary up to ±100°F (37.8°C). The FLT93C is easily field-configured or factory preset, providing flexibility, accuracy, and stability for all multiple process sensing and switching requirements.


The FLT93C Flow Switch is suitable for 0.75 to 4-in. (19.05 to 101.6 mm) sanitary tubing process lines and connects with a secure tri-clamp fitting for easy removal for inspection and servicing.


In addition to CIP systems, other pharmaceutical uses of the FLT93C Flow Switch include compendial water systems (WFI, PW and HPW) and solution preparation systems (buffer solution). Special options are available for applications requiring more corrosion-resistant, wetted materials such as Hastelloy C and Class 1, Div 1 and 2 hazardous areas.


The FLT93 Series Switch is a dual-function instrument that indicates both flow and temperature, and/or level sensing in a single device. Dual 6A relay outputs are standard and are independently configurable to flow, level or temperature. One standardized, field-configurable FLT93 FlexSwitch control circuit satisfies virtually any combination of application requirements. FCI’s advanced FlexSwitch technology can be packaged in integral or remote configurations for installation flexibility.


The FLT93C Switch beats the heat, too. It is available with a choice of sensors including one that is suitable for process temperatures up to 350°F (176.67°C) and one that is suitable for temperatures up to 500°F (260°C).  Hazardous approvals available for the FLT93C Switch include ATEX and EAC/TRCU.

For Flow Service - Setpoint Range:

  • Water-based Liquids: 0.01 to 3.0 fps [0.003 to 0.9 mps]
  • Hydrocarbon-based Liquids: 0.01 to 5.0 fps [0.003 to 1.5 mps]
  • Air/Gas: 0.25 to 120 sfps [0.08 to 37 smps] at standard conditions of 70° F [21.1° C] and 14.7 psia [1.013 bar(g)].

Accuracy: (whichever reading is higher)

  • Liquids: ± 0.5% reading or ± 0.04 fps [± 0.012 mps]
  • Gases: ± 0.5% reading or ± 2 sfps [± 0.06 nmps]

For Temperature Service:

  • Accuracy: ± 2° F [±1° C]
  • Repeatability: ± 1° F [± 0.6° C]

Response Time: As low as 3 seconds.


Enclosure: NEMA 4X/IP66 Rated. Standard: Polyester power coated aluminum, with single 1" NPT conduit port. Optional: Stainless steel. Optional: Dual-conduit port, aluminum, with 1/2" NPT or M20 metric conduit ports.


Compliances and Agency Approvals: FM, FMc, ATEX, IECEx, EAC/TR CU, Inmetro. CE mark. PED, CRN. Meets EC directives for EMC and LVD. Probe complies with Canadian Electrical code requirements of ANSI/ISA 12.27.01-2011 as a single seal device.

FM/FMc:XP, Class 1, Div. 1 Groups B,C,D
DIP, Class II/III, Div. 1, Groups E,F,G
T4, Ta = 60°C, T3A, Ta = 60°
ATEX:II 2 G Ex d IIC T6...T2 -40°C to 60°C Gb
IECEx:Ex d IIC T6 or T5
Tamb (housing) = -40° to +40°C, T6
Tamb (housing) = -40° to +60°C, T5
Tp (sensing element) = -40° to 77°C, T4
Tp (sensing element) = -40° to 177°C, T2


Optional N.I.S.T. Flow Calibration Services: Factory N.I.S.T. calibration in air or water is available as an option for customer-specified setpoint(s) or a flow curve based on the media ranges specified above.


Materials of Construction: All welded 316L stainless steel electro-polished to 20 Ra for all wetted surfaces.


Process Connection: Sanitary flange: Insertion Length and Short Leg Tee Size

  • 1.17 in. [35 mm] for 0.75 in. Tee 
  • 1.25 in. [32 mm] for 1 in. Tee
  • 1.93 in. [49 mm] for 1.5 to 2 in. Tee
  • 2.75 in. [70 mm] for 3 to 4 in. Tee

Operating Temperature:

  • Standard: -4° to +350° F  [-20° to +177° C]
  • Optional: -100° to +500° F  [-73° to +260° C]

Operating Pressure: To 2,000 psig  [138 bar(g)]


Control Circuit Operating Temperature: -4° to +140° F [-20° to +60° C]


Universal AC/DC supply. Input terminals and jumpers on circut board select specific power.

AC108-132V13W, 100mA max.
AC207-253V*14W, 50mA max.
AC18-28V7W, 230mA max.
DC21-30V7W, 230mA max.

* AC mains preset by factory: FM & FMc as 108-132 Vac; All others as 207-240 Vac 


Relay Contacts: Field configurable dual SPDT or single DPDT rated 6 amps at 115 Vac, 240 Vac or 24 Vdc. Hermetically sealed relays are available as an option.


Output Signal: Analog DC voltage related to flow or level/interface signal and proportional to temperature.


Electrical Connection: 1-in. female NPT 


Remote Configuration: Available as an option with customer-specified interconnecting cable length.