Gate Valve Tamper Switch
Keylion® gate valve tamper switch, widely known in the field as an OS&Y supervisory switch, acts as your main monitoring unit for fire control valves. We designed it to track the open status of outside screw and yoke valves, making sure your sprinkler system keeps its water supply ready at all times.
Inside you'll find a spring‑loaded lever that moves together with the valve stem. If the valve gets partially or fully shut, this lever will activate the built‑in SPDT switches, and a trouble signal will go straight back to your fire control panel. You'll commonly see this unit fitted on commercial risers, industrial fire mains, and mechanical rooms in high‑rise buildings.
Product Specifications
| Product Model | OSY2 (Safe Signal Series) |
| Device Type | Outside Screw and Yoke (OS&Y) Gate Valve Supervisory Switch |
| Application | Monitors the open position of OS&Y type gate valves in fire sprinkler systems |
| Switch Contacts | Two sets of SPDT (Form C) synchronized switch mechanisms |
| Contact Rating | 10.0 A @ 125/250 VAC; 2.5 A @ 24 VDC |
| Operating Temperature Range | 32°F to 120°F (0°C to 49°C) |
| Enclosure Rating | NEMA 3R / IP24 rated (Indoor/Outdoor use) |
| Enclosure Material | Cover: Die-cast zinc with red powder coat finish Base: Die-cast aluminum |
| Conduit Entrances | Two open holes for 1/2" conduit (one open, one knock-out) |
| Valve Sizes Accommodated | Fits most OS&Y valves from 1" to 12" (25mm to 300mm) |
| Trigger Criteria | Activates within 1/5th of the total valve travel or 2 full revolutions |
| Shipping Weight | Approx. 2.8 lbs (1.3 kg) |
| Security / Tamper Cover | Includes tamper-resistant screws (requires special wrench for removal) |
FAQ
Q1: How to install an OS&Y gate valve supervisory switch?
A: Follow these key steps for installation.
Prepare the Valve: First, fully open your gate valve, then pick a suitable spot on the valve stem to cut the groove.
File the Groove: Create a clean, shallow V‑shaped or square groove on the stem. Aim for roughly 3/16" deep and 1/2" wide, so the switch actuator rod slides into place without binding.
Mount the Bracket: Fit the mounting bracket over the valve yoke, then tweak its position until the whole switch assembly runs parallel with the valve stem.
Position the Switch: Push the switch's actuator rod straight into that machined groove, then fasten everything tight using the supplied U‑bolts and hardware.
Verify Tension: Double‑check the spring tension on the actuator rod. It needs enough force to pop smoothly out of the groove the second the valve stem starts moving.
Q2: How many turns of the valve triggers a supervisory alarm?
A: The alarm has to activate within two (2) full rotations of the handwheel, OR once the stem travels 1/5 of its total stroke - whichever condition happens first. This tight requirement means even small, unauthorized adjustments or tampering to this vital water supply valve get picked up right away by your fire alarm panel.
Q3: Can an OS&Y gate valve supervisory switch be mounted horizontally or upside down?
A: You can install this switch onto a horizontal valve pipe, but never flip the housing upside down (conduit entry holes facing upward).
This unit carries a NEMA 3R weatherproof rating, and that protection depends on gravity to drain water away from internal electronics. If you mount it upside‑down or at a bad angle, rain, condensation or sprinkler water can leak inside through the conduit openings. Water pooling inside will corrode contacts and end up killing the switch entirely. Always set it up so conduit openings point down toward the ground.
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