Availability: In stock SKU: OP921
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OP921 Siemens Photoelectric Smoke Detector.

OP921 Siemens Detector Placement

Although no specific spacings are set for the detectors used for a clean air application, use 30-foot center spacing (900 sq ft) from NFPA Standard 72 initiating devices chapter, if practical, as a guide or starting point for a detector installation layout. This spacing, however, is based on ideal conditions–a smooth ceiling, no air movement, and no physical obstructions.

In some applications, therefore, considerably less area is protected adequately by each smoke detector. This is why it is mandatory to closely follow the installation drawings. In all installations place the detector on the ceiling, a minimum of 6 inches from a side wall, or on a wall, 6 inches from the ceiling.

If you have any questions regarding detector placement, follow the drawings provided or approved by Siemens Industry, Inc. or by its authorized distributors. The detector placements shown on these drawings were chosen after a careful evaluation of the area that is protected.

Such factors as air currents, temperature, humidity, pressure, and the nature of the fire load were carefully considered. Especially noted were the room or area configuration and the type of ceiling (sloped or flat, smooth, or beamed). Siemens Industry, Inc.’s extensive experience in the design of the system assures the best detector placement by following these drawings.

OP921 Siemens To Avoid Nuisance Alarm

Do not locate the detectors where excessive smoke concentrations exist under normal conditions, or in areas of prolonged high relative humidity where condensation occurs. Do not locate the detectors next to an oil burner, kitchen, or garage where exhaust fumes can trigger an alarm. Other causes of false alarms are dust accumulation, heavy concentrations of steam, heavy pipe or cigar smoke, and certain aerosol sprays.

OP921 Siemens Air Currents 

Before a detector can sense a fire, the products of combustion or smoke must travel from the fire to the detector. This travel is especially influenced by air currents; therefore, consider air movement when designing the system.

Datasheet OP921.

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Additional information

Weight 0.25 lbs
Dimensions 6 × 6 × 0.5 in
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