IOM SPDB Iss.2 ENG
March 2019
Page 2 of 6
1 Specification & Principle of Operation
1.1
Introduction
The SpinklerSense SPDB type is a water flow alarm switch, approved to EN 12259-5 and for use under the
LPCB rules for automatic sprinkler installations.
The SPDB is a thermal dispersion type flow switch for use on wet sprinkler systems approved for use through
sizes 2 to 6” (50 to 150mm).
1.2
Construction & Specification
Sensor Probe & Connection:
304 Stainless Steel, R¾ (3/4” BSP Male Taper thread)
Sensor & Relay box:
Painted die cast Aluminium enclosures to IP65
Max Operating Pressure:
20 bar
Operating Temperature Range: 2 to 68
C
Input Voltage:
24V D.C.
Flow Switch Output:
1x DPCO Relay, 30V D.C., 2A
Adjustable Delay:
Type SPDB 30: 0 to 30 seconds
Type SPDB 90: 0 to 90 seconds
Flow-rate Sensitivity:
The switch will operate at all flow-rates above 60 L/min
The switch will not operate at flow-rates less than 10 L/min
1.3
Principle of Operation
Water flow passing the sensor probe causes a change in relative temperature between the sensor probe legs,
which is directly proportional to the flow-rate in the pipe. The sensor circuit measures this flow precisely,
comparing it to the set alarm flow-rate. When the measured flow-rate reaches or exceeds the set flow rate, the
flow switch output operates immediately or after the set delay period. When the flow-rate reduces below a set
point, the switch automatically resets.
