Bounce-free contact behavior
The mercury-wetted contact forms a stable conductive bridge when closed, reducing contact bounce that can disturb timing or pulse measurements.
Mercury Wetted Relay
Mercury Wetted Reed Relays for Bounce-Free Precision Switching
Mercury wetted reed relays are specialized precision switching components valued for bounce-free closure and low, stable contact resistance in selected test and measurement applications.
Zero contact bounceStable contact resistancePrecision pulse/test pathsCompliance review needed
What this component is used for
Low-level signal repeatability
Stable contact resistance can be valuable in precision switching paths where repeatability is more important than general-purpose power handling.
Specialized, not universal
Mercury devices are not the default modern choice; they are selected when the application benefit justifies regulatory and mounting considerations.
Application details
ATE and semiconductor validation
Useful where switching bounce or contact resistance variation can distort timing-sensitive measurements.
Pulse and timing circuits
Can support repeatable pulse routing when the relay is operated within datasheet limits.
Legacy replacement
Used when replacing established mercury-wetted designs that require similar electrical behavior.
Precision instrumentation
Suitable for selected low-level or controlled switching paths after orientation and compliance review.
Mercury-wetted series at a glance
HGMR — miniature
- 50 W, 500 VDC
- 2 A carry
- Molded SIP, dense matrices
HGJR — SMT J-lead
- 100 W, 500 VDC
- 5 A carry
- Surface-mount J-lead
HGSR — industrial
- Forms 1A/2A/1C/2C
- 4000 VDC isolation
- 8.5 A carry, rugged
HVR — mercury HV
- 1000 VDC switching
- 2000 VDC stand-off
- 50 W, zero-bounce HV
MH — high power
- 5000 VDC switching
- 10 A carry
- 10 kVDC isolation, pulse power
HGFR — multi-pole
- 1–4 Form A poles
- 1500 VDC, 3 A
- Flat / vertical mount
Why the mercury film matters
Zero contact bounce
The liquid mercury bridge closes without the mechanical bounce of a dry contact, which matters for high-speed counting and clean pulse/timing edges.
Self-renewing resistance
The wetted contact surface is renewed on every operation, so contact resistance stays low and stable rather than drifting as a dry contact wears.
High surge tolerance
The liquid bridge tolerates brief inrush/surge current without the contact welding that can affect dry contacts under pulse load.
Reading a model code: HGFR12-4A-01
HGFR = high-voltage mercury-wetted family; 12 = coil voltage option (05 / 12 / 24 VDC); 4A = four Form A (normally open) contacts; 01 = package/terminal/shield option. Representative starting points: HGMR12-1A001, HGSR12-2A04, HVR1A12-HG, MH12-1A8K. Most mercury-wetted parts are position-sensitive — install within roughly vertical ±30° unless the datasheet states otherwise.
Selection factors engineers should confirm
- Confirm mounting orientation; many mercury-wetted devices are orientation-sensitive.
- Check RoHS, regional restrictions and end-product compliance before design-in.
- Verify switching voltage/current and contact form against datasheet.
- Do not use where shock, vibration or mounting angle violates relay requirements.
- Consider dry reed alternatives when zero-bounce mercury performance is not required.
Engineering note: Because mercury is hazardous and regulated, this page positions mercury wetted relays as specialized components for qualified applications, not as a universal replacement for dry reed relays.
Need help selecting a relay or contactor?
Send voltage, current, load type, coil voltage, package constraints and target application. SHR AUTOSENSOR can recommend a standard series or custom design path.