Siemens Industry, Inc.
Building Technologies Division
P/N 315-034800-3
These instructions are written in accordance with the instal-
lation guidelines of NFPA 72, National Fire Alarm Code, and
CAN/ULC-S524, The Installation of Fire Alarm Systems.
Detector Device Storage
DO NOT install this detection device until all construc-
tion is completed.
DO NOT store this detection device where it can be con-
taminated by dirt, dust, or humidity.
When using this detector with a protective detec-
tor guard such as the DGH-11 from Siemens In-
dustry, Inc., or the STI 8100IS, be sure to install
per the instructions supplied with the guard and
set the ASD setting to duct detector per the detec-
tor programming instructions located on page 2 of
this document.
HFPO-11 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 and CAN/ULC-S524, if practical, as a
guide or starting point for a detector installation layout. This
spacing, however, is based on ideal conditions–smooth ceil-
ing, no air movement, and no physical obstructions. In some
applications, therefore, considerably less area is protected ad-
equately 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, 4 to 6 inches from the ceiling.
If you have any questions regarding detector placement, fol-
low the drawings provided or approved by Siemens Industry,
Inc., or by its authorized distributors. This is extremely impor-
tant! 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. Es-
pecially noted were the room or area configuration and the
type of ceiling (sloped or flat, smooth or beamed). Siemens In-
dustry, Inc.’s extensive experience in the design of the sys-
tem assures the best detector placement by following these
drawings. Sound engineering judgment by qualified person-
nel must be followed.
To Avoid Nuisance Alarms
Do not locate the detectors where excessive smoke concen-
trations 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 alarm are dust accumulation, heavy concen-
trations of steam, heavy pipe or cigar smoke, and certain aero-
sol sprays.
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. While combustion
products tend to rise, drafts from hallways, air diffusers, fans,
etc., may help or hinder the travel of combustion products to
the detector. When positioning a detector at a particular loca-
tion, give consideration to windows and doors, both open
and closed, to ventilating systems, both in and out of opera-
tion, and to other factors influencing air movement. Do not
install a detector in the air stream of a room air supply dif-
fuser. It is better to position a detector closer to an air return.
The distance that products of combustion or smoke travel
from a fire to the detector is not usually the shortest linear
route. Combustion products or smoke usually rise to the ceil-
ing, then spread out. Average ceiling heights of 8 to 10 feet
do not abnormally affect detector response. High ceilings, lo-
cated in churches, warehouses, auditoriums, etc., do affect
detector response and should be considered.
Special Ceiling Construction Factors
Ceiling obstructions change the natural movement of air and
combustion products. Depending on the direction of smoke
travel, joists and beams can slow the movement of heated air
and smoke, while pockets between them can contain a re-
duced level of smoke. Take obstructions created by girders,
joists, beams, air conditioning ducts, or architectural design
Figure 1
HFPO-11
Photoelectric Detector
Installation Instructions
Model HFPO-11
