Hochiki SDP-2 User Manual

Hochiki sdp-2 duct probe installation instructions, Introduction, Mounting position

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Hochiki Europe (UK) Limited

Page 1 of 4





Hochiki's Duct Probe housing allows a standard
photoelectric smoke detection device, either a
conventional detector or an analogue sensor, to be
mounted on the outside of an air duct for the purpose of
monitoring the air within the duct. Air within the duct is
drawn via a pipe into the duct probe's housing. This
allows constant sampling with a standard, LPCB
approved smoke detector and makes smoke detection
within the duct simple, effective and easy to maintain.
Compatible Hochiki devices that can be used within the
SDP-2 are:


ACA-E (inc all variants)
ALG-E (inc all variants)
ALG-EN (inc all variants


SLR-E3 (inc all variants)

SLR-E3N (inc all variants)

Compatible Hochiki Bases that can be used within the
SDP-2 are:




and YBO-R/6RS.

Mounting Position

The SDP-2 should be installed with the arrow on the
cover corresponding to the direction of airflow in the
duct. The SDP-2 can be placed horizontally or vertically,
on the top, side or bottom of the duct. Hochiki
recommends that the SDP-2 is mounted away from
heating, cooling or humidity devices following the same
guidelines for flow monitors.

Example of location after

change of duct direction

Example of location

after air inlet

A distance of three times the duct diameter should be
left before a damper, filter or change of duct direction,
and five times the diameter after these devices.

NOTE: The word “diameter” has been used throughout.
In the case of square-section ducts this should be read
to mean width.

Air Flow Parameters

The SDP-2 Duct Probe will operate within the following
air velocity range and should be installed to meet this
requirement: 1.0ms


to 10.0ms


Hydraulic Diameters

Circular Duct

Rectangular Duct

Location Examples

(GX represents duct probe)

Fan Damper

Silencer Battery

Change of duct direction

Duct branching

Duct narrowing or expansion

Air “control“ equipment

Installation Procedure

STEP1 - Selecting Pipe Length

The supplied 600mm sampling pipe can only be used
with ducts up to a maximum diameter of 600mm, but the
pipe can be shortened if required (see Step 2).

For ducts with a diameter greater than 600mm use the
1200mm sampling pipe cut to size but penetrating the
whole width of the duct (see “Large Diameter Ducts” on
Page 2).

For ducts with a diameter greater than 1200mm contact
Hochiki Europe Customer Support for advice
([email protected]).