125 BP Series Bypass Adjustable Flow Monitor

125 BP flow switch: compact precision via bypass technology

The 125 BP flow switch stands out for its high resolution and wide adjustability. Because technicians can easily set the switch point themselves via the variable orifice in the main line, this monitor offers maximum control with minimal installation space. In addition, the hermetic separation between the medium and the electronics guarantees safe, long-term operation.

Why the 125 BP series is the ideal choice

Thanks to the versatile choice of materials (stainless steel, brass or Teflon®), engineers use the 125 BP flow switch in a wide range of industries. The monitor performs excellently in the following sectors:

• Gas analysers: For monitoring sample streams.
• Vacuum systems: For detecting minimal gas flows.
• Wet stations: For monitoring process liquids in the electronics industry.
• Industrial liquid lines: Where high resolution at low flows is required.
• Cooling systems: For reliable protection of sensitive equipment.

How does the bypass mechanism work?

The operating principle of the 125 BP flow switch relies on the pressure differences within the unit:

1. Rest position: When there is no flow, the magnetic piston rests at the bottom of the bypass bore.
2. Pressure difference: As soon as flow starts, the orifice in the main line creates a small bypass flow.
3. Switching: This flow lifts the piston, after which the magnet activates the reed switch. The required flow condition is signalled immediately.
4. Reset: When the flow drops below the limit value, the piston moves down and immediately deactivates the switch.

Technical specifications 125 BP series

Installation and engineering support

Always mount the 125 BP flow switch vertically with the inlet port at the bottom. We also strongly recommend using a 10 micron filter to safeguard the precision of the bypass orifice.

Do you have an application with higher temperatures? We optionally offer versions that withstand temperatures up to +171 °C. For specialist advice on chemical resistance or higher flows, you can also look at our 500 BP series or check the website of our partner ChemTec.