Two transmitting LEDs light one chamber from different angles while a single infrared receiver reads both. Three channels against one address — 1, 2 and 4 — is the quickest confirmation at a panel that a dual-optical head is fitted.
The panel forms a ratio between forward and backward readings; defined bands of that ratio let the algorithm hold back on steam and dust while still answering smoke. Mounting is unchanged: same 117 mm body, same base, same loop position.
Technical data
| Label marking | O2H |
| Sensing | Forward and backward scatter optical, plus heat |
| Analogue channels | 1, 2 and 4 |
| Standards | EN 54-7:2000 A1:2002 and EN 54-5:2000 A1:2002; A2:2006 not applicable to this part |
| Baffle ring | Black (silent) |
Specifications from 4188-1073 issue 3.
Compatibility
Shares the S4-700 base with the rest of the white sensor line, and takes S4-FLUSH for a recessed tile finish cut at 140 mm diameter. If the specification asks for black, the matching head is S4BK-711.
Installation
Configuring the base terminal as a monitored fire input rather than an output calls for a 470 ohm series resistor at the contact and a 10 kilohm end-of-line resistor.
Full details: S-Quad dual optical heat sensor — installation data — 4188-1073 issue 3 · 28 pages · dual-angle chamber description, three-channel allocation
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