Calorimetric Flow Switch FS 10|11|15|20 EX



  • Corrosion Proof Construction
  • Reliable & Well Built
  • Self-Teaching Technology

Calorimetric Flow Switch FS 10|11|15|20 EX

The calorimetric flow switch is designed for the monitoring of thermally conductive liquids. The big advantage of this type of flow switch is the fact that it is usable also in explosive atmosphere.

Key technical properties

Flow switch FS Ex 10/11/15/20 flow switch is certified for use in the following areas with explosive atmosphere:

I M1 Ex ia I Ma

II 1G Ex ia IIC T4..T6 Ga

II 1D Ex ia IIIC Txx°C Da

The flow switch for liquids is made in four versions. These are as follows:

FS 10Ex – 1× status output (depending on flow velocity)

FS 11Ex – 2× status output (depending on flow velocity)

FS 15Ex – 2× status output (1× depending on flow velocity and 1× on temperature)

FS 20Ex – 1× status output and 1× current output (depending on flow velocity)

The flow rate is indicated by ten LEDs within the measurement range, and you can select the boundary for making/breaking the contact in the same graduation. The measuring cycle takes from 4 seconds to 8 seconds with recommended measurement range 4 ÷ 150 cm/sec (for default setting, the measurement range is 4 ÷ 400cm/sec). If the piping is empty, the sensor behaves identically as in the case of zero flow rate.

Two standard lengths of the bar type sensor are offered according to piping ID at the installation site, selecting either a bar type sensor 65 mm or 125 mm in length as needed. If the flow rate of medium is to be monitored in a pipe smaller than DN25 (or the flow velocity is below the sensor range for the given pipe diameter), it is advantageous to use an adapter block with the corresponding flow velocity and thereby ensure proper functioning and maintain the installation conditions. The adapters are designed for the short version of 65mm sensor with the use of direct neck with G½“pipe thread. Individual designs of adapter blocks are as follows:

  • ​FS adapter block DN20/G3/4“pro 5 ÷ 100 l/min. (rozměr 150×50×40 mm)
  • FS adapter block DN15/G1/2“pro 2 ÷ 40 l/min. (rozměr 150×50×30 mm)
  • FS adapter block DN10/G1/4“pro 0,4 ÷ 20 l/min. (rozměr 150×50×30 mm)
  • FS adapter block DN4,5/G1/4“pro 0,1 ÷ 5 l/min. (rozměr 70×50×30 mm)
  • FS adapter block DN2,7/G1/4“pro 0,075 ÷ 2 l/min. (rozměr 70×50×30 mm)

Key features:

  • Designed for use in explosive atmosphere.
  • Possibility to use another status output (version FS 15) for monitoring of temperature according to setting.
  • For FS 20 design, in addition to the making contact also 4 ÷ 20 mA current output
  • 10 LEDs to display the current flow and adjusted switching limits.
  • ‘Self-teaching’ system with the possibility of Qmin and Qmax settings
  • Possibility to set switching limits (pre-set neutral zone)
  • Electrical connection through M12 (4-pin) connector
  • Continuous control of the sensor for correct operation
  • Full corrosion-proof construction
  • Calorimetric Flow Switch FS 10|11|15|20 EX


Manufacturer: Comac Cal

Part Ref: CFS


Media Type: Liquids

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Product Specification

Below is the product specification of the Calorimetric Flow Switch FS 10|11|15|20 EX from Comac Cal. If you require further information about this flow switch, please contact our expert customer service advisors on 01722 442 307.


​24 V ± 10 % DC with polarity reversal protection (other upon request)

Input Power

1.5/4 VA

Electrical Connection

M12 × 1, 4 pin connector.

Flow sensor degree of protection


Velocity flow range

4…400 cm/sec


±2.. ±8 cm/sec


2…8 cm/sec


2× flush-type push button

Media Temperature

0…+80 °C

Ambient Temperature

-10…+55 °C

Material in contact with media

Stainless steel 1.4404

Maximum Pressure

63 bar

Electrical connection

M12 × 1, 4 pin connector.

Process connection

According to DIN2353, with the M16 × 1.5 union nut through the 24° ring into the direct socket with pipe thread (G1/2“; G1/4“; M14 × 1.5; NPT1/4“)

Sensor design installed.

compact, separated.


10× three-colour LED (flow velocity)

1× LED (temperature – for FS 15 only)