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REMOTE INTELLIGENT SENSOR - AREA MONITOR
Page 4-8 Instruction 2772-0803
NOTE: The sections below do not refer to
the modest changes in flow that occur over
a period of time and are quickly adjusted
for with the appropriate potentiometer.
4.20.1 A FAULTY PUMP. If this is the case,
change the pump. Note that there are two pump
types, which are fitted depending upon the RIS
model. Refer to Sections 4.8 & 4.11 for guidance
including typical pump running current. Check
Section 5 for the correct catalog number.
4.20.2 A BADLY FITTED INPUT TUBE. Check
to ensure that the input tube(s) is correctly fitted
and that no leakage is occurring.
4.20.3 A FAULTY TAPE GATE SEAL. This
problem is only likely after several years operation.
It can occur through distortion, or wear, of the seal
as a result of the opening and closing of the gate
over an extended period. Replacing the seal re-
quires special knowledge, and should be referred to
one of our Service Centers.
4.20.4 LEAKING OR LOOSE TUBING. Check
to ensure that all of the pipe work in the mechani-
cal chassis is sound and properly connected.
4.21 EXCESSIVE TAPE USE
Cassettes lasting appreciably less than 30 days
may be due to:
4.21.1 MONITORED CONCENTRATION
LEVELS HIGH. During periods when significant
levels are monitored, the system will use each track
only once; it will also operate in the ‘time mode’ if
the sample concentration is high enough. Both
conditions will increase tape consumption.
4.21.2 EXCESSIVE STEP LENGTH. This can
occur because an undue amount of tape is pulled
through the gate at each step. The average step
length should be 0.027" to 0.032" (7 to 8 mm) and
the method of measuring it is described in Section
4.10.6. This condition, if present, may be caused by
high take-up clutch torque, a weak pinch roller arm
spring, a maladjusted tape gate, or a combination of
these factors. Rectification is considered a Service
Center repair.
4.22 TAPE BREAKAGE
Tapes can be damaged by careless insertion of a
new cassette. Take care, as it is difficult to repair a
broken tape. If the tape breaks during normal
operation check that the tape is not damp which
would reduce its strength. Tape breakage can also
occur if the tape gate gap is too small. If this is the
case, the take-up clutch will pull against the con-
straints of the gate causing the tape to break. The
tape-gate gap can be checked as in Section 4.10.6.
If the two ends of a broken tape can be ‘fished
out’ of the cassette body they can be repaired by
careful joining with adhesive tape. The join must
then be completely wound onto the take-up spool so
that it does not pass through the tape gate when
operation resumes.
CAUTION
Do not touch tape with bare fingers to
avoid contact with chemicals on the tape.
4.23 LIGHT FAULTS
If Light Faults occur, check (in the TEST Mode)
that the light level values are at, or close to 220. If
not, adjust as covered in Section 4.4. Make sure
when adjusting that the tape in the gate, when the
adjustment is made, is clean and not stained.
If the light level when checked is found to be
correct at, or close to, 220 make sure that it is not
possible that some external bright light (natural or
artificial) does not shine directly up the input
tube(s).
Remember that opening the tape gate without
putting the system into the TEST Mode can cause a
light fault as well as a spurious gas alarm.
If no apparent reason for frequent light faults is
found refer to one of our Service Centers for assis-
tance.
4.24 DOOR FAULT
If the door fault is intermittent or the door
needs excessive tightening of the screws to turn it
off, or if it cannot be turned off, adjust the switch.
This is covered in Section 4.7.