Det-Tronics U7652B, C Unitized UV/IR Flame Detector - Manual (Page 5)

The U7652C with 4 to 20 ma output uses the dc cur-
rent level for indicating system status conditions.
Table 2 shows the detector status conditions corre-
sponding to each current level.
Data Logger
The optional data logger provides status recording
capability for the detector. Important status data
such as power-up/down, faults and alarms are date
and time stamped as they occur and stored in non-
volatile memory. Up to 510 events can be recorded:
up to 63 fire alarm events and up to 447 non-fire
events. This data is later uploaded to a personal
computer (PC) where it can be displayed, saved
and/or printed.
The Data Logger system consists of a special elec-
tronic module and mother board assembly (one for
each U7652 Detector in the system) and a W6300
Detector Inspector™, which provides the interface
between the electronic module and the PC.
The W6300 Detector Inspector is furnished with an
RS-232 serial port for connection to the serial port of
the PC. Communication between the data logger
module and the PC uses the Modbus RTU protocol,
with the data logger module configured as a Modbus
slave.
The Inspector software (included) can operate on
most Intel® Pentium® based computers running
Microsoft Windows 95/98.
The real time clock in the module is furnished with
battery back-up to ensure correct operation in the
event of a power failure. The clock provides second,
minute, hour, day, month and year data.
The detector’s relays and LEDs function exactly the
same as the standard U7652 Detector; however, the
auxiliary relay and 4 to 20 ma output are not available.
GENERAL APPLICATION INFORMATION
Response Characteristics
Table 3 lists the typical response distances of the
U7652 Detector to various flammable materials. The
detectors were sighted to observe the fire at center
axis ±10 degrees and were set for a 0.5 second time
delay. Response is dependent on the type of fuel,
the temperature of the fuel, and the time required for
the fire to build. As with all fire tests, results must be
interpreted according to an individual application.
Important Application Considerations
In applying any type of sensing device as a fire
detector, it is important to know of any conditions that
can prevent the device from responding to fire, and
also to know what other sources besides fire can
cause the device to respond. Read through the fol-
lowing discussion of these factors before installing the
U7652 detectors.
ARC WELDING
The U7652 ignores arc welding beyond 10 feet from
the detector. However, the UV sensor will respond to
the intense UV radiation generated by the arc weld-
ing, and at distances closer than 10 feet the heated
metal from the welding can become a false alarm
source for the IR sensor. Arc welding should not be
performed within 10 feet of the detector.
BLACKBODY SOURCES
Any object with a temperature greater than 0° Kelvin
(–273°C) emits IR radiation. The hotter the object, the
3 95-8385
Table 2—Current Level for Detector Status
(U7652C with 4 to 20 ma Output)
* ±0.5 ma
** Available only when 3 second response
is selected
Current Level* Detector Status
0 ma Fault
2 ma oi Fault
4 ma Normal Operation
8 ma IR Only
12 ma UV Only
16 ma** Instant Alarm
20 ma Fire Alarm
Table 3—U7652 Typical Response Distances
Fuel Distance from U7652
Acetone (1 ft, x 1 ft.) 45 feet (13.7 meters)
Diesel (1 ft. x 1 ft.) 40 feet (12.2 meters)
Gasoline (1 ft. x 1 ft.) 50 feet (15 meters)
JP4, 5, and 8 (2 ft. x 2 ft.) 100 feet (30 meters)
JP4, 5, and 8 (3 ft. x 3 ft.) 150 feet (45 meters)
JP4, 5, and 8 (4 ft. x 4 ft.) 150 feet (45 meters)
JP4, 5, and 8 (10 ft. x 10 ft.) 150 feet (45 meters)
Methane (30-inch plume) 35 feet (10.7 meters)
Methanol (1 ft. x 1 ft.) 35 feet (10.7 meters)
Toluene (1 ft. x 1 ft.) 50 feet (15 meters)
Wood Shavings 50 feet (15 meters)
(One pound excelsior)
Wood Stack 50 feet (15 meters)
(10 inch x 10 inch crib)