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Product Description
MSA-1J Proximity Switch For Watertight Door Alarm System
Product Introduction
The Marine Proximity Switch is a critical solid-state sensing component within a vessel's Watertight Door Alarm System. It provides non-contact, highly reliable real-time position feedback for each power-operated watertight door. Typically mounted on the door frame or adjacent structure, this sensor detects the precise position of the door leaf (or a designated target on it) to determine whether the door is fully CLOSED and SECURED or in the OPEN position.
Unlike mechanical limit switches, the proximity switch operates without physical contact, eliminating wear, friction, and the risk of failure due to corrosion or mechanical shock. It generates a clean electrical signal that is transmitted directly to the system's local control unit and central status repeater panel. This signal is fundamental for triggering the mandatory pre-closure audible/visual alarms, confirming the door's sealed status for watertight integrity, and providing remote indication on the bridge.
Engineered for the harsh marine environment, the switch features a robust, watertight (high IP rating), and corrosion-resistant stainless steel or brass housing. It is designed to withstand constant vibration, humidity, and wide temperature fluctuations. Its reliable, maintenance-free operation and long service life ensure continuous compliance with SOLAS regulations and classification society rules, forming the essential "on/off" truth signal for the entire safety and monitoring system.
Drawing

Technical Data
| Main Power | AC220V±10% |
| Spare Power | DC24V(+30%~-25%) |
| Environment Temperature | -10℃~+55℃ |
| Environment Humidity | ≤95% |
| Alarm Sound Pressure Level | 75dB~95dB |
| VDR Data Protol | RS485 |
Watertight Door Alarm System

Watertight Door Alarm System Connection Diagram
