Installation Instructions

10271 1-1/2" FPT Cooling Water Flow Switch


The Maretron 10271 is an accessory for the SIM100 Switch Indicator Module. The 10271 has a set of normally closed contacts that will open whenever a flow of cooling water of a user-settable amount is detected.



Please follow these instructions to connect the 10271 to the NMEA 2000 network via a Maretron SIM100 Switch Indicator Module. The wiring diagram appears in Figure 1. The diagram shows a connection to channel #1, but connections to other channels are similar. Please refer to the original manufacturer’s instructions packaged with the product for additional details including setting of the switch activation flow rate.



1.     Install the two wires from the 10271 to a free switch channel on the SIM100. The two wires are interchangeable. The example in Figure 1 shows the flow switch connected to switch channel 1, terminals SW1A and SW1B.


2.     Use a Maretron DSM150 or DSM250 display or Maretron N2KAnalyzer software to set the switch channel mode (indicated as “Channel #x Mode” on the DSM250) for the appropriate channel to the “No End of Line Resistor” setting. For this example, you would set “Channel #1 Mode” to “No End of Line Resistor”.


3.     Supply Power to the NMEA 2000 network, Verify that the switch channel indicates an “on” (normal) state using Maretron N2KView software, N2KAnalyzer, or other product capable of displaying switch indicator state.


4.     Start cooling water flow through the 10271 and verify that the switch channel indicates an “off” state.


Figure 1 - Wiring Diagram










Device Specifications



Inside Diameter

1.5” (38.1mm)

Outside Diameter

2.25” (57.2mm)


4.36” (110.7mm)


6.69” (169.9mm)

Activation Flow Rate

6 – 8 GPM (22.7 – 30.3 LPM)


Normally Closed


1-1/2” FPT Female

Switching Rating


Switching Voltage (Max)

300VAC / 300VDC

Maximum Switching


Heat Resistance, Continuous

210°F (99°C)

Maximum Pressure

120 PSI @ 72°F
8.3 bar @ 22°C

External Fasteners

18-8 Stainless Steel


CPVC Schedule 80


5’ (1.5m) Marine Grade Tinned Wire Leads















For installation support, please contact:


Maretron, LLP

9014 N. 23rd Ave #10

Phoenix, AZ 85021-7850

Telephone: (+1) 866-550-9100