Description
The 5MM Mercury Tilt Switch is a miniature, gravity-activated electrical switch consisting of a sealed glass or metal envelope containing a small bead of liquid mercury and two electrical contacts. When the switch is oriented with the contacts at the lower end, gravity causes the conductive mercury bead to bridge the contacts, closing the circuit. When tilted beyond a threshold angle, the mercury rolls away from the contacts, opening the circuit.
The switch operates as a normally open (NO) device in its upright position, with the mercury completing the circuit only when gravity holds it against the contacts. Unlike ball-type tilt switches, mercury switches offer very low and consistent contact resistance and can be manufactured for extremely low tilt angles, making them suitable for precision orientation detection in legacy thermostats, safety devices, and level controls. The hermetic sealing eliminates oxidation and allows higher load switching than mechanical alternatives.
Critical limitations: Mercury is toxic and the product is not RoHS compliant. The switch provides on/off detection only, not angle measurement. The glass envelope is fragile and can break if dropped, releasing hazardous mercury. For new designs, RoHS-compliant ball tilt switches (e.g., SW-520D) are recommended. The maximum switching voltage is typically 12V DC for small mercury switches, though larger variants may handle higher voltages.
Features
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Gravity-Activated Switching: Mercury bead bridges contacts when oriented correctly; opens when tilted.
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Normally Open (NO) Operation: Circuit is open when upright (contacts at top), closes when tilted past threshold.
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Low and Consistent Contact Resistance: Mercury provides reliable electrical contact with minimal resistance variation.
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Precise Tilt Detection: Can be manufactured for very low tilt angles, more precise than ball switches.
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Hermetically Sealed: Glass or metal envelope protects contacts from oxidation.
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Compact 5mm Size: Miniature envelope suitable for space-constrained installations.
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Quiet Operation: No mechanical clicking noise during switching.
Technical Specifications
| Parameter | Specification |
|---|---|
| Type | Mercury tilt switch |
| Size | 5mm diameter (approx. 13mm length per one listing) |
| Contact Type | Normally Open (NO) |
| Operation | Gravity/mercury bead |
| Maximum Voltage | ~12V DC (typical for small switches) |
| Maximum Current | ~300mA (per one listing) |
| RoHS Status | Not compliant (contains mercury) |
| Contact Material | Silver (per one listing) |
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