MKCM WATER SIGNAL flow switches combine a magnetic float and reed switch with a transparent standard flow tube. They provide an electrical indication when the specified flow threshold is crossed, while the standard acrylic tube permits local observation of float movement. Every listed size is available as a distinct OFF or ON contact model.
Construction and operating specifications
| Parameter | Specification |
|---|---|
| Fluid | Water |
| Maximum temperature | 60°C |
| Pressure resistance | 1 MPa |
| Mounting orientation | Upward, downward or sideways; observe the intended flow direction |
| Standard connections | Rc female; R male or mixed arrangements on request |
| Maximum operating voltage | 300 V AC/DC |
| Maximum operating current | 0.5 A AC/DC |
| Contact capacity | 50 VA |
| Switch setting | Fixed at shipment; specify the required operating flow |
| Flow tube | Acrylic, standard version |
| Protective cover | CAC902 |
| Fittings | C3604 brass; SUS version can be requested |
| Spring | SUS304 |
| Magnetic float | Acrylic or nylon |
| O-ring | Nitrile rubber, standard version |
| Lead length | 200 mm standard; other lengths or cabtyre cord on request |
| Heat-resistant option | Up to 100°C; brass flow tube and fluororubber seal |
| Pressure-resistant option | Up to 5 MPa; brass flow tube and fluororubber seal |
| Special-version visibility | Float cannot be visually inspected through the brass tube |
Switching action and factory settings
A magnetic float moves as the water flow changes. The reed switch changes contact state when the specified flow threshold is crossed. Choose an OFF version when the contact should open as flow decreases, or an ON version when it should close as flow decreases. Keep the full TW-OFF or TW-ON suffix in the order and electrical documentation. The switching threshold is set before shipment and is not a field-adjustable control setting.
Selection range versus maximum line flow
The setpoint-selection column gives the interval within which a factory operating threshold can be specified. The maximum line-flow column is a separate limit for water passing through the unit. For example, the 20 body group permits a threshold from 0.1 to 4 L/min and a maximum line flow of 10 L/min; a 10 L/min maximum does not mean that a 10 L/min threshold can be ordered for that size. The 45 or 42 body group lists 5–30 L/min threshold selection and 100 L/min maximum line flow.
Complete water-model dimensions and flow data
| Model | Port | Length (mm) | Width (mm) | Depth (mm) | Minimum bore (mm) | Factory setpoint selection range (L/min) | Maximum line flow (L/min) |
|---|---|---|---|---|---|---|---|
| MKCM20-1TW-OFF | Rc1/8 | 80 | 30 | 22 | 6.5 | 0.1 to 4 | 10 |
| MKCM20-1TW-ON | Rc1/8 | 80 | 30 | 22 | 6.5 | 0.1 to 4 | 10 |
| MKCM20-2TW-OFF | Rc1/4 | 80 | 30 | 22 | 6.5 | 0.1 to 4 | 10 |
| MKCM20-2TW-ON | Rc1/4 | 80 | 30 | 22 | 6.5 | 0.1 to 4 | 10 |
| MKCM20-3TW-OFF | Rc3/8 | 86 | 30 | 25 | 6.5 | 0.1 to 4 | 10 |
| MKCM20-3TW-ON | Rc3/8 | 86 | 30 | 25 | 6.5 | 0.1 to 4 | 10 |
| MKCM30-2TW-OFF | Rc1/4 | 100 | 44 | 32 | 9.5 | 0.5 to 10 | 20 |
| MKCM30-2TW-ON | Rc1/4 | 100 | 44 | 32 | 9.5 | 0.5 to 10 | 20 |
| MKCM30-3TW-OFF | Rc3/8 | 104 | 44 | 32 | 9.5 | 0.5 to 10 | 20 |
| MKCM30-3TW-ON | Rc3/8 | 104 | 44 | 32 | 9.5 | 0.5 to 10 | 20 |
| MKCM30-4TW-OFF | Rc1/2 | 110 | 44 | 32 | 9.5 | 0.5 to 10 | 20 |
| MKCM30-4TW-ON | Rc1/2 | 110 | 44 | 32 | 9.5 | 0.5 to 10 | 20 |
| MKCM35-4TW-OFF | Rc1/2 | 124 | 49 | 44 | 13.5 | 3 to 15 | 50 |
| MKCM35-4TW-ON | Rc1/2 | 124 | 49 | 44 | 13.5 | 3 to 15 | 50 |
| MKCM35-6TW-OFF | Rc3/4 | 124 | 49 | 44 | 13.5 | 3 to 15 | 50 |
| MKCM35-6TW-ON | Rc3/4 | 124 | 49 | 44 | 13.5 | 3 to 15 | 50 |
| MKCM45-6TW-OFF | Rc3/4 | 142 | 62 | 50 | 18.0 | 5 to 30 | 100 |
| MKCM45-6TW-ON | Rc3/4 | 142 | 62 | 50 | 18.0 | 5 to 30 | 100 |
| MKCM45-8TW-OFF | Rc1 | 142 | 62 | 50 | 18.0 | 5 to 30 | 100 |
| MKCM45-8TW-ON | Rc1 | 142 | 62 | 50 | 18.0 | 5 to 30 | 100 |
All 20 listed standard water-model entries are retained. Dimensions are in millimetres and flow values are in L/min. The full model, connection and required installation envelope must be checked together. TW identifies the water-series order form shown in these tables.
Cast protective housings can show individual dimensional variations at the casting surface. Check the installation drawing and available clearance, particularly overall width, before machining a mounting arrangement.
Electrical integration and alarm duty
Use the 300 V AC/DC voltage limit, 0.5 A AC/DC current limit and 50 VA contact capacity together. The maximum voltage and current must not be multiplied into a load that exceeds the contact-capacity limit. Prevent overcurrent and wiring faults, and assess nearby magnets or ferromagnetic components because the reed switch is magnetically actuated. The manufacturer recommends alarm-detection duty wherever practicable; consider the effect of a malfunction when integrating the contact into other equipment.
Water-specific materials and special versions
The water versions list an acrylic or nylon magnetic float, a SUS304 spring and a nitrile-rubber O-ring in the standard acrylic-tube construction. Heat-resistant versions up to 100°C and pressure-resistant versions up to 5 MPa use a C3604 brass tube with fluororubber sealing. The float cannot be visually inspected in those brass-tube versions. Specify the intended water conditions, threshold, material option and lead arrangement when requesting a special construction.
Installation and commissioning
The spring-supported construction allows upward, downward or sideways mounting. This concerns orientation, not interchangeability of the inlet and outlet: follow the intended flow path and selected fitting arrangement. Keep the viewing area accessible. Match the actual water conditions and required flow with the selected model, check the pipe connection and material compatibility, and inspect for leakage or tube damage after installation. Verify the chosen contact action and operating flow under the intended installed conditions before relying on the alarm signal.
Product and dimensional illustrations
Ordering information
Specify the complete water-series model, inlet and outlet thread forms, normal water flow, operating temperature and pressure, and available installation space. State OFF or ON action, the required switching flow within the listed range, lead length and any heat- or pressure-resistant option.