FSP900 Series:thermal flow switch|Water Flowmeter

FSP900 Series:thermal flow switch|Water Flowmeter

FSP900 Type: insertion flowmeter|hermal flow switch|Water Flowmeter

  • Product Features

    • Flow range: water: 0.03~3 m/S oil: 0.03~3 m/S
    • Applicable pipe diameter size: DN8~DN350
    • Detection fluid: water, oil
    • Protection level: IP67

    FSP900 water flow switch

    is a device that automatically controls and protects water flow. When the water flow is changed, when the force generated by the water flow on the target is dynamic, the control circuit absorbs or disconnects, so as to achieve the purpose of automatic control. Water flow switches are widely used in HVAC air conditioning systems

    FSP900 water flow switch

    Product Featured Design
    FSP900 FGT TW Page4

    FSP900 water flow switch
    Remote monitoring design

    FSP900 FGT TW Page11

    FSP900 FGT TW Page10


    The working principle of FSP900 water flow switch:

    The FSP900 water flow switch will be installed on the chilled water outlet of the chilled water unit and the chilled water/chilled water outlet of the water-cooled chiller. Normally closed water flow switch (when the air conditioning system is operating normally, the water flow switch control circuit is closed, here refers to the state of the water flow switch is normally closed) The working process is: when the water flow reaches a certain value, the FSP900 water flow switch is closed After that, the compressor starts and the air-conditioning system starts to run. If there is water leakage in the air conditioning system or other reasons that reduce the water flow of the system, when the water flow drops to a certain value, the water flow switch will be turned off, and the compressor will stop at the same time, and the HVAC air conditioning system will stop running.

    1. Cooling water outlet pipe; 2. Water-cooled chiller condenser; 3. Water-cooled chiller evaporator; 4. Chilled water outlet pipe; 5. FSP900 water flow switch.

    Installation position of FSP900 water flow switch in air conditioning system

    The function of FSP900 water flow switch:
    When the air-conditioning system has sufficient water flow, the FSP900 water flow switch is closed, after which the compressor is started, so as to ensure the safe and efficient operation of the air-conditioning system.

    1) When the chilled water flow is too small, the evaporator load is insufficient, the evaporating temperature is low, the cooling capacity decreases, and the operation efficiency decreases.

    2) When the chilled water flow is extremely small, the evaporator load is seriously insufficient, the evaporation temperature is very low, the evaporator freezes (or even freezes), and the compressor suction pressure is very low. If the system is operated for a long time under this working condition, the compressor will be damaged due to difficulty in oil return.

    3) When the cooling water flow of the water-cooled chiller is too small, the heat dissipation efficiency of the condenser is low, and the heat of the fluorine system cannot be dissipated in time, which causes the system's condensing temperature to rise, the cooling capacity to drop, and the operating efficiency to decrease.

    4) When the cooling water flow of the water-cooled chiller is extremely small, the heat dissipation of the condenser is seriously insufficient, the condensing temperature rises to a high level, and the compressor discharge temperature is extremely high. If the system is operated for a long time under this working condition, the compressor will be damaged due to the carbonization of the lubricating oil.

    Design flow value:

    Illustrate the method of calculating the closed and open flow values ​​of the chilled water flow switch of a chiller with a certain cooling capacity.

    Knowing that the cooling capacity of the chiller is 32kW, try to calculate the closed and open flow values ​​of the matched water flow switch.

    1) Calculate the closed flow value of the water flow switch. The design water flow (m3/h) of the unit evaporator can be calculated according to formula (1):

    Taking into account the induction error of the water flow switch, the open flow value of the water flow switch is (3.1±0.2) m3/h.

    Application of FSP900 water flow switch:

    The FSP900 water flow switch uses stainless steel corrosion-resistant inserts with high pressure resistance to detect water flow conditions. When there is water flow, it quickly captures the flow rate and temperature of the flowing water and drives the action output to provide a water flow status signal.

    The installation requirements are relatively high, and the resistance is relatively large when installed in small pipe diameters, and it cannot be installed on curved pipelines. When installed in a small pipe diameter or when the water flow is small, it is easy to be shaken by the water flow and move frequently. The FPS900 water flow switch also solves the traditional design flow switch problem, and it is easy to cause the target to break when installed at the large pipe diameter elbow. An effective solution is obtained.

    The static pressure of the pipeline impacts the bellows, and the bellows is prone to fatigue due to frequent movements.

    FSP900 FGT TW Page5


    FSP900 water flow switch solves the cause of the target fracture of the target flow switch:
    Solve the problem that the force of the target of the target type flow switch is related to the water flow speed and the area of ​​the target. The larger the flow rate and the area of ​​the target, the greater the force acting on the target. Usually installed in a large pipe diameter water flow switch for better For sensing water flow, the longest target is often installed on site. Due to the large force acting on the target, the target is excessively bent and loses its elasticity. In severe cases, the target is broken.

    The target type flow switch usually needs to be more than 5 times the pipe diameter from the elbow and valve. Due to the small area of ​​the computer room of the current building, it is impossible to guarantee enough straight pipe sections to install the water flow switch. For example: DN300 pipe diameter, before and after the water flow switch It is almost impossible to guarantee a straight pipe section of 1500m. This is a very important reason for the failure of many on-site water flow switches.

    In a curved pipe, due to the diversion effect of the curved pipe wall, the inner flow velocity increases, and the outer flow velocity gradually decreases, forming a trapezoidal velocity distribution law of each flow section, causing the entire target to be unevenly stressed and broken .

    The impact of the water hammer generated every time the pump starts and stops will cause the target to be excessively bent or broken. The larger the pipe diameter, the greater the risk.

    The FSP900 water flow switch can be installed closer to the elbow or valve, which can greatly reduce the straight pipe section required to install the target flow switch, which saves the engineering cost and greatly improves the stability of the water flow protection. The factory has been widely used.

    Installation method of FSP900 water flow switch

    FSP900 FGT TW Page6


    FSP900 water flow switch full pipe installation

    FSP900 FGT TW Page7



    • Water flow switch


      The principle of the water flow switch is to measure the water flow. You can measure the pressure drop at both ends of the valve, orifice plate, and then check the pressure drop and flow curve of the valve or orifice plate to get the accurate flow, which can be obtained by the pressure drop method. Flow rate has been widely used in HVAC water side systems and flow measurement instruments. The application of the differential pressure switch in the HVAC system is mainly controlled according to the resistance and flow curve of the HVAC equipment. The water-side heat exchanger in the HVAC (tube-in-tube type, shell-and-tube type, tube-plate type and commonly used plate heat exchanger) , Water filters, valves and pumps have their pressure drop and flow performance curves. As long as the measured pressure difference on both sides of the pressure difference switch is compared with the preset value, the flow can be accurately controlled. The differential pressure switch is used as the flow control in HVAC with accurate flow control, no additional resistance to the water system, no requirement for the diameter of the water pipe, and no disturbance of water flow. It can replace any form of target flow switch. In the target type flow switch, it can avoid the false flow caused by the cavitation of the water pump, and has a very accurate reset flow and disconnect flow.


      水流量開關Thermal Flow SwitchIn some large-scale equipment and machines, circulating water is usually used to cool the unit, so that the operating temperature of the unit is kept within a reasonable range. When the cooling water system fails, if the water flow stops, it will cause the temperature of the unit to rise, affect the normal operation of the unit, and may cause the unit to burn out in serious cases. Under normal circumstances, a water flow switch is installed in the pipe of the cooling water system to monitor the flow status of the cooling water in real time. Once the cooling water stops flowing, the water flow switch will send an alarm signal to the central control room so that the central control room can be timely Deal with it to avoid accidents.


      There are many ways to detect the fluid flow state. Generally, water flow switches are roughly divided into three types. One is the early mechanical flow switch, also known as the baffle type flow switch. Its principle is to push the baffle to deflect through the flow of water. Then touch the micro switch to act. The advantage of this kind of mechanical flow switch is that it is easy to use and cheap. The disadvantage is that the mechanical structure will be worn out. In the case of poor water quality, the action is not very stable; one is the thermal flow switch, its principle Yes, the amount of liquid flow is different, and the amount of heat taken away is different. By detecting the amount of heat loss, the flow of water can be detected. The advantage of this kind of water flow switch is that there are no moving parts and no wear and tear, which greatly enhances its life and stability. The disadvantage is that the price is slightly more expensive than the mechanical type; the last type is the differential pressure flow switch, this type of flow The switch groundbreakingly controls the flow rate accurately according to the curve of the heat exchanger pressure drop and the flow rate, and does not produce any pressure drop on the air conditioning system.


      Baffle type flow switch


      Principles and characteristics

      The mechanical part of the baffle-type flow switch is safely isolated from the electronic part. The product does not contain bellows that can easily cause failures, electrical components do not directly contact metal components with large temperature differences, and there is no problem of rust caused by condensation water on electrical components. It has a variety of types for customers to choose from to suit different applications. Imported magnetic switch is used as the electrical action part. It has a small disconnection and reset flow. It is the preferred flow protection product for central air-conditioning and industrial fluid control.



      The baffle type flow switch is a gas-liquid dual-purpose type, which can be widely used in industrial automation/mechanical equipment/air compression industry/refrigeration and air-conditioning fields. In industrial occasions, it is specifically applied to water-cooled welding machines, laser equipment cooling systems, vacuum coating machines, and electric furnaces. , Polycrystalline silicon ingot furnace, etc. The water flow switch magnet is not in the flowing water channel, and can be used in the sewage system and can work normally.


      Technical Parameters

      △Voltage: 250V (max.)

      △Maximum current and capacity: 1A, 50VA

      △Connection method: Directly attached

      △Output: SPST magnetic sensitive switch (factory setting normally open)

      △Pressure resistance: 25bar, 50bar can be customized

      △Average pressure loss: 0.01bar (at maximum flow)

      △Working temperature: -20...90℃

      安裝位置Installing way△Shell protection grade: IP65

      △Material: Wetted shell: Nickel-plated brass

      Baffle: stainless steel

      Seal: PTFE


      Applicable medium
      Water, gas, oil


      Thermal flow switch



      1. The probe has been specially treated, and there is a protective film on the outer surface, which is completely anti-corrosion and anti-scaling;

      2. The potentiometer is directly driven by the drive screw to set it without disassembly, so it is completely waterproof

      3. Original dual adjustment technology, more convenient adjustment and more accurate display

      4. The original double relay output can be used to make the control easier

      4. LED lights can reflect the current flow

      5. Ultra-small shell, integrated design, all made of stainless steel, practical and beautiful


      Technical Parameters

      1. Setting method: two potentiometer settings (no disassembly, directly driven by the drive screw to set the potentiometer), one to set the action point and one to set the range

      2. Measuring range: water 0-10m/s, oil 0-15 m/s, gas: 0-30 m/s

      3. Working voltage: DC24V, AC/DC110V, AC/DC220V

      4. Working current: <60mA

      5. Output mode: relay output, PNP output, NPN output, double alarm output

      6. Operating temperature: normal temperature type -20-80℃, high temperature type 0-150℃

      7. Reverberation time: 1~10S, typical value 2S

      8. Initialization time: about 8S

      9. Electrical protection: reverse phase, short circuit, overload protection

      水流量開關Thermal Flow Switch

      Differential pressure flow switch


      Characteristic description

      固定式壓差流量開關Fixed differential pressure flow switchThe fixed single set point differential pressure switch is specially developed for high-volume OEM customers. The professionals of ACOL first communicate with the customer to understand the characteristics of the customer’s product and customize the appropriate differential pressure switch for the product, so that the water The flow control is reasonable and accurate. The user cannot change the set value of the differential pressure switch at the site, thus ensuring that the set value of the differential pressure switch cannot be changed, reducing the failure and hidden dangers of the unit due to improper installation and design of the on-site water system. ACOL company fully considers the actual situation of the user's application and knows that the user is concerned about flow control. The fixed set point differential pressure switch can convert the differential pressure setting value of the differential pressure switch into a specific heat exchanger according to the customer's requirements. According to the flow protection value, we can customize the pressure difference switch that meets the customer's flow index according to this requirement, and the customer only needs to detect it according to the flow rate during the inspection.

      Technical Parameters

      △Storage temperature: -29~82℃

      △Using environment temperature: -20~71℃

      △Using medium temperature range: -20~93℃

      △High and low voltage side connection port: 1/4 SAE (7/16 "-20UNF), G1/4 (1/4 "NPT) etc. optional

      △Maximum allowable static pressure: 10bar

      △Maximum allowable pressure difference: 5bar

      △Set point repeatability deviation: ±1%

      △Output form: One set of SPDT dry contact output, one/two outputs are optional, when one output is factory set normally open

      △Switch parameters: 10A (max.) 250V (max.)

      △Connection method: DIN 43650C connector/direct attached line (105℃ flame-retardant sheath line 2X0.75mm2 or 3X0.75mm2) optional

      Applicable medium

      Water, air


      Infrared water flow switch



      Also called infrared water flu detector, it is applied to the water inlet of the new high-tech industry of instant electric water heater in the water heater industry to detect the water flow into the instant electric water heater and control the startup and shutdown functions. It is especially suitable as a supporting device for constant temperature instant electric water heater, which can transmit the detected water flow and temperature to the control system in time to achieve the purpose of rapid constant temperature. It is also suitable for the flow detection needs of similar products.


      product manual

      The infrared flow sensor is installed at the inlet of water heaters and other products to detect the water flow rate. When the water flows through the product, the impeller rotates and its speed changes with the flow rate. The infrared flow sensor outputs the corresponding pulse signal It is fed back to the controller, and the controller sends out corresponding instructions according to the size and on-off of the water flow. The internal design of this product adopts the structure of physical principles and has the function of anti-backflow signal, which eliminates the phenomenon of dry burning of the signal when the product is in the backflow of water; due to the completeness of the product design, it is effective without the use of magnetic core control. It prevents the magnetic impurities in the water from being adsorbed on the impeller, and the long-term use signal will not change with the prolonged use of the product. In addition, there is no magnetic field as the signal source, and the shaking of the impeller does not affect the signal strength, so the gap between the impeller and the casing can be enlarged to ensure that the impeller will not be stuck or jammed due to poor water quality for long-term use.

      Within a unit flow rate, the more pulse parameters are sent, the accuracy and consistency of the product will be improved accordingly. When the infrared flow sensor has a flow rate of 1 liter per minute, about 20 pulse signals per second, and about 1200 pulse signals per minute can be sent out.

  • Model


    Measuring Range

    Water:0.03~3 m/S

    Oil:0.03~3 m/S

    Sensor Lengh(mm)


    Sensor Dimension


    Sensor Material


    Output Type


    Communication type


    Operating Pressure

    4 Mpa(Max.60Mpa)

    Ambient Temperature

    -20~80 ℃,8 5 % R H

    Operating Temperature


    OLED Display

    Flow rate display / Temperature display
    Multi display interface

    Housing Material


    Protection Level

    IP 67

    Connection Type

    Female M18-1.5

    Operating Voltage

    24 Vdc

    Power consumption



    2 Sets of 4-20mA (flow+temperature) + 2 Sets of alarm contacts
    Relay (flow+temperature) + 2 sets of alarm contacts
    NPN/PNP (flow+temperature) + 2 sets of alarm contacts
    RS485 (flow/temperature)

    Option Parts

    F01: Welded joint
    F02: Three-way threaded joint
    F03: Three-way flange joint

    Remote monitoring
    Optional function

    IoT_D: Rail installation MI/O+RS485
    IoT_R: Rail installation RS485
    IoT_N: Economical installation of RS485

  • FSP900 FGT EN Page2

  • Series
    Unit: mm
    Piping Size
    Flow Output signal Temperature Output signal communication Power
    Relay NPN
    4-20mA Relay NPN
    4-20mA RS485 24V
    DN8~DN100 M
    With Optional With With Optional With With With --
    DN80~DN450 M
    With Optional With With Optional With With With --
  • Order Information





    Sensor Size




    Water: 0.03~3 m/s; Oil: 0.03~3 m/S; Air: 2~30 m/S For sensor rod length (mm): 45.5 (standard type)




    Water: 0.03~3 m/s; Oil: 0.03~3 m/S; Air: 2~30 m/S For sensor rod length(mm): 72.5 (long shaft type)






    Fluid Type





    Water (Standard type)











    Output Type






    Flow/Temperature: 4~20mA+2 Sets of Relays






    Flow/Temperature: 4~20mA+2 Sets of NPN






    Flow/Temperature: 4~20mA+2 Sets of PNP







    Specify the length of the sensing rod (unit: mm)







    The total product length tolerance is ± 5mm






    Features, specifications and dimensions are subject to change without notice






    Maximum length. 200mm






    Please contact our service center








    Sensor Material








    Stainless steel 304









    Power supply









    DC 24V










    Optional accessories: connector










    No(Standard type)










    Welding joint (applicable: DN25~DN350)










    Three-way screw joint (applicable: DN8~DN50)










    Three-way flange (applicable: DN25~DN150)











    Optional function: remote monitoring transmitter











    No(Standard type)











    Rail-mounted type (applicable: MIO: AI/DI input)











    Rail-mounted type RS485











    Economical Type RS485












    Optional function: SMM software












    No(Standard type)
















































    ODM type













    Logo Print













    FGT Logo













    Customer Logo



























    Complete Ordering Code


    *Note:Using customer Logo launch to more than 100 united for  one year