System Sensor DH500ACDC - Manual (Page 7)

Step 6. Install the Filters
Most duct installations are subject to dust accumulation.
System filters remove a large percentage of this contamina-
tion, but cannot remove all of it. Dust inside the duct detec-
tor causes problems. First, very fine particles of dust can
enter the detector sensing chamber and cause the unit to
alarm. Second, the accumulation of dust and dirt necessi-
tates a more frequent periodic cleaning schedule, which
can result in substantial cost and/or down time.
Disposable sampling tube filters can greatly reduce the nui-
sance alarms caused by dust, and can also significantly
extend the maintenance interval. To install the sampling
tube filters, insert the filter adapter into the exhaust tube
and push the filter onto the adapter tube on the left, as
shown in Figure 6. Then, install the other filter over the
end of the inlet sampling tube.
Filters require periodic cleaning or replacement, depending
on the amount of dust and dirt accumulated. Inspect the fil-
ters at least quarterly – more often if dust accumulation
warrants it. Replacement filters can be ordered from
Notifier. (Exhaust tube/intake tube filter P/N F36-05-00.)
Filters rarely have a significant effect on the behaviour of
smoke. As a result, even a filter that is as much as 90%
clogged does not significantly affect the entry of smoke into
the duct detector housing. Therefore, visual inspection is
usually all that is necessary to determine if filters need
replacement.
CAUTION
Step 7. Perform Detector Check
7.1 Air Flow
1. To verify sufficient sampling of ducted air, use a
manometer to measure the differential pressure created
from air flow across the sampling tubes. The pressure
should measure no less than 0.01 inches of water and no
greater than 1.20 inches of water.
2. To determine that smoke is capable of entering the sens-
ing chamber, conduct a visual examination to note any
obscurations around the sensing chamber. If a smoke
test is required, blow smoke from a cigarette, cotton
wick, or punk directly at the smoke detector head. It is
important to plug the exhaust and sampling tube hole to
prevent ducted air from blowing smoke away from the
smoke detector head. Record all test records in the
Detector Test Log at the end of this manual.
Remove the plugs after testing or the detector will not
sense smoke in the air duct.
7.2 Alarm Tests
Before replacing the duct housing cover, check the detector
interconnections. Check the DH500ACDC as follows:
A. M02-04-00 Magnet Test
1. Make sure power is applied to the detector.
2. Position the painted surface of the test magnet against
the housing next to the rib molded onto the outside
of the housing (see Figure 7).
3. The LEDs on the detector should latch on as should
any accessories (PA400, RA400ZA, RTS451) and the
alarm condition verified at the control panel. The
control panel must be active to initiate an alarm.
CAUTION
SAMPLING TUBE
FILTERS
SAMPLING TUBE
MOUNTING
SCREWS
DETECTOR HEAD
EXHAUST
FILTER ADAPTER
DETECTOR BASE
INLET SAMPLING TUBE
FOAM GASKET
Figure 6. Sampling tube filter installation:
A78-2451-00
D500-07-00 7 I56-432-11R