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Recommended monitoring levels based on
compliance to ANSI/BSR ASHRAE 15-2007 and
ASHRAE Safety Code 34-2007 have been developed
and are listed in Table 8-1 and Section 6, RLDS
Hardware Specifications.
Setting the unit at these recommended alarm levels
will satisfy the needs of most users. However, the
PPM levels generated by system leaks into the
environment are greatly influenced by the volume of
air in the sampling area, air circulation, size of the
leak, distance to the monitoring point, and a host of
other variables. In some cases the set points may need
to be adjusted either up or down to achieve effective
monitoring. Please contact your representative
(770-425-2724) for assistance in obtaining these
levels.
2.4. Response to the
Presence of Multiple
Refrigerants
The RLDS is a refrigerant level monitor, not a gas
analyzer. You must program the monitor to test for a
specific refrigerant in each zone, and it will only
return accurate concentration readings for that
particular refrigerant. If a leak occurs of another
refrigerant gas type, the monitor may return false
readings.
Most applications only require detection of a
single refrigerant and the problems that are associated
with monitoring multiple gases are rarely an issue. If
there is a possibility of multiple refrigerants leaking in
the same sampling zone, you should consider
carefully which refrigerant compound you program
the unit to monitor, or make system design
considerations to cover this event. Please consult your
sales engineer for assistance in setting up the RLDS
system to cover this event.
2.5. Suggested Location of
Sampling Points
At the point of origin of a refrigerant leak, the gas is
highly concentrated. As the refrigerant is dispersed
into the air, the gas molecules diffuse, causing a
dilution of the original concentration. The RLDS
measures the refrigerant concentration at the sample
collection point, so if the termination of the collection
4 • RLDS I&O Manual
line is not at the exact point of the refrigerant leak, the
unit will read a diluted mixture of the refrigerant gas
and air and may require adjustment of alarm levels.
The farther away an RLDS sample point is from a
refrigerant leak, the longer it will take to detect the
leak, and the lower the concentration of refrigerant in
the air will be; therefore, place the termination of the
collection line as near as possible to the point where
refrigerant leaks are the most likely.
It should also be noted that refrigerant gas is
heavier than air and tends to collect below the point of
a leak; therefore, samples taken near the floor will
have a greater concentration of gas than those
collected above the source of a leak; therefore,
sampling points should ideally be located as close as
possible to the source of potential leaks. If this is
impractical, then the alarm setpoints should be
adjusted for that zone to compensate for the dilution
of the refrigerant gas. Line-end filters should be
mounted 12" (30 cm) to 18" (45 cm) above the floor.
DO NOT block any of the zones. Unused zones may
be disabled by setting the distance parameter to zero
feet in the zone setup screen.
The RLDS should be centrally located in the
mechanical room and be readily accessible for easy
visual monitoring and servicing. The combined
length of sample tubing, plus exhaust tubing, should
not exceed 1200 feet (365 meters) for any zone. The
fresh air purge line should draw from an area that does
not contain any refrigerant gas. The exhaust line
should run to an outside location if possible. The
combined length of the purge line and the exhaust line
cannot exceed 300 feet (91 meters).
Ideally, two to three pick up points spaced around
each chiller will provide sufficient coverage. It may
be necessary to perform a "smoke" test of the
mechanical room to determine the best locations. The
smoke test would provide the pattern of air currents
present in the mechanical room.
NOTE: For information about using the
RLDS in wet locations, see Section 3.3.6., Con-
siderations.
026-1309 Rev 8
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