MK OIL SIGNAL indicators provide a compact visual check that oil is moving through a pipe. A ball or float moves inside a transparent tube. This is a flow-presence indicator, not a quantitative flowmeter: the catalog example ranges relate to VG68 oil at 40°C and must not be treated as a universal calibrated measurement range.
Construction and operating specifications
| Parameter | Specification |
|---|---|
| Fluid | Oil |
| Maximum temperature | 80°C |
| Pressure resistance | 1 MPa |
| Transparent tube | Acrylic |
| Fittings | C3604 brass |
| Spring | SUS304 |
| Ball | Nylon 66; cylindrical float may be used depending on specification |
| Threaded connection options | Rc female standard; R male or mixed arrangements on request |
| SUS fitting option | Available on request for the threaded version |
What the visual indication means
The ball or float responds to the fluid passing through the transparent tube, giving a direct visual indication of oil movement. This family does not provide a quantitative flow reading. The threaded-model minimum and maximum values below are examples for VG68 oil at 40°C. Oil viscosity and temperature affect the indication, so the same apparent ball movement must not be treated as a transferable L/min calibration for another oil or temperature. Copper-tube rows, where present, retain the separately listed maximum-flow values.
Models and dimensions
| Model | Port | Length (mm) | Width (mm) | Example minimum flow: VG68 at 40°C (L/min) | Example maximum flow: VG68 at 40°C (L/min) |
|---|---|---|---|---|---|
| MK15-1TL | Rc1/8 | 50 | 15 | 0.005 | 0.5 |
| MK25-1TL | Rc1/8 | 68 | 25 | 0.05 | 5 |
| MK25-2TL | Rc1/4 | 68 | 25 | 0.3 | 5 |
| MK25-3TL | Rc3/8 | 74 | 25 | 0.3 | 5 |
| MK30-2TL | Rc1/4 | 90 | 30 | 1.5 | 10 |
| MK30-3TL | Rc3/8 | 94 | 30 | 1.5 | 10 |
| MK30-4TL | Rc1/2 | 100 | 30 | 1.5 | 10 |
All dimensions are in millimetres. Match the complete model designation, connection type and installation length. Threaded R male and Rc female connections are distinct from copper-tube outside-diameter connections.
Alternative connection designations
| Published connection-variant example | Connection arrangement |
|---|---|
| MK25-3TOL | R male connections at both ends |
| MK25-3TOML | R male inlet connection |
| MK25-3TMOL | R male outlet connection |
These are ordering examples for alternative threaded arrangements. Confirm the dimensions and availability for the requested fitting arrangement; the standard TL dimensional row must not be assumed to cover every modified connection.
Installation and operating checks
The spring-supported design allows upward, downward or sideways mounting. This flexibility concerns the mounting orientation; connect the inlet and outlet according to the intended flow path. Keep the viewing area accessible so the oil movement can be inspected during operation. Check the specified temperature and pressure limits against the actual oil circuit and verify material compatibility with the oil. Inspect the transparent tube, fittings and any seals for leakage or damage, and confirm visible oil movement after commissioning. A visual indicator supplies local information; any required automatic shutdown or remote alarm must be specified as part of the system design.
Product and dimensional illustrations
Information to provide when ordering
Specify the complete model or configured series, oil type or viscosity, normal delivery conditions, inlet and outlet connections, and available mounting space. For copper-tube models, state the tube outside diameter. For threaded models, distinguish R male from Rc female connections.