HFS paddle flow switches detect increasing or decreasing liquid flow and provide a changeover contact for pump, valve or alarm control. Applications include HVAC water circuits, industrial cooling, pump protection and water-treatment pipelines. Use them with water, ethylene glycol or other nonhazardous liquids compatible with the selected wetted materials.
The mechanical paddle actuates a microswitch as flow changes. An adjustable operating point allows the switch to be matched to the piping and required flow condition. The family uses an ABS cover, a metal mechanism base, a stainless steel paddle and brass or stainless steel process-connection options.
| Model | Mounting thread size | Documented construction variants |
|---|---|---|
| HFS-15 | 1/2in | HFS-15A engineering type; HFS-15B standard type |
| HFS-20 | 3/4in | HFS-20 |
| HFS-25 | 1in | HFS-25A engineering type; HFS-25B standard type |
The mounting connection size is different from the main pipeline diameter. Choose the switch connection to match the fitting and the paddle arrangement to suit the main flow pipe. Three-plate and five-plate paddle options are listed.
| Parameter | Specification |
|---|---|
| Control principle | Paddle / target |
| Switch function | Flow increase or decrease detection; SPDT changeover microswitch |
| Maximum liquid pressure | 1715kPa, stated as 17.5kgf/cm² |
| Ambient temperature | 0°C to 60°C |
| Liquid temperature | -10°C to 100°C, with the fluid kept unfrozen |
| Manual electrical rating | 220VAC, 15A |
| Additional listed contact ratings | 125V or 250V, 15A at power factor 1.0 |
| Terminal connection | Screw terminals with dedicated grounding screw |
| Cover | ABS plastic; 1/2in conduit opening in the reference manual |
| Mechanism base | Iron base with zinc-plated hardware |
| Body / process connection | Brass or stainless steel |
| Paddle | Stainless steel; three-plate or five-plate configurations |
The operating manual specifies a maximum liquid temperature of 100°C. Select the actual switch and load circuit according to its marked electrical rating.
| Main pipe diameter | Approximate activation range |
|---|---|
| 1in | 18-50L/min |
| 1-1/2in | 30-105L/min |
| 2in | 50-155L/min |
| 2-1/2in | 75-200L/min |
| 3in | 100-260L/min |
| Terminal | Function |
|---|---|
| 1 | Common |
| 2 | Normally open; connects to terminal 1 when flow rises to the switching point |
| 3 | Normally closed; connects to terminal 1 when flow falls to the lower switching point |
| Reference drawing dimension | Value |
|---|---|
| Cover width | 79mm |
| Cover depth | 64.5mm |
| Reference overall height shown | 130mm |
| Horizontal offset shown | 50mm |
Install in horizontal pipe or vertical upward flow, with at least five pipe diameters of straight run on each side. Align the housing arrow with flow direction and keep the paddle clear of pipe walls or other restrictions. Vertical installation requires consideration of gravity. Do not use a downward-flow location.
The switch is supplied at the minimum flow setting. Turn the adjustment screw counterclockwise for a higher operating flow or clockwise for a lower setting. Avoid excessive clockwise adjustment. Move the paddle several times and confirm that the microswitch clicks when the lever returns. If it does not, turn the adjustment screw counterclockwise until the return click is restored.
Disconnect power before wiring or commissioning. Use the dedicated grounding screw and avoid force that could shift the microswitch or deform the base. Check three operating cycles with the connected system and replace the cover after adjustment. The English manual includes the full installation and commissioning instructions.
