NuAire LabGard ES NU-565-400, Руководство по эксплуатации и техническому обслуживанию

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OM0301
August 20 Page 16 of 105
5.2.7 Exhaust/Supply Duct Installation Guidelines
The exhaust/supply systems must provide conditions similar to that under which the cabinet was certified to meet
its stated performance. The following guidelines should be observed when installing exhaust/supply air ductwork
for either existing plant exhaust systems, or a new exhaust system.
1. Adequate room make-up air inflow to replace exhausted air. Air diffusion rate is not to exceed velocity of
100 LFPM (.51 m/s) to minimize disruptive air currents. If laboratory is to be pressurized, follow
guidelines in ANSI/AIHA Z9.5 Laboratory Ventilation.
Room Make-Up Air Requirements (CFM/CMH) Utilizing Concurrent Balance Values
Model Room make-up air volume
NU-565-400 815 / 1385
NU-565-600 1275 / 2166
2. Adequate plant exhaust system capability. The exhaust system is usually adequate if it can provide the
rated exhaust flow and static pressure.
3. All duct losses must be considered and added to the cabinet loss in selecting the exhaust blower, for a
new exhaust system (i.e. duct diameter, length and number of elbows, etc.).
4. Adequate supply air capability (if used). The supply air system is usually adequate if it can provide the
rated supply air at 0.0 inches water gauge positive.
5. The supply air must be interlocked with the operation of the cabinet's internal downflow blower in order
to prevent downflow air from being forced out of the front of the cabinet when powered off or during
night setback conditions. Nuaire provides fan relay contacts for this purpose.
6. All ductwork should be securely anchored to the building construction in manner to be free from vibration
and swaying under all conditions of operations.
7. Sheet metal gauges and seams should be in accordance with the current edition of the ASHRAE guide.
A minimum of 20 gauge for round duct is required to prevent duct collapse due to high static pressure
conditions (square duct will require heavier gauge material).
8. All ductwork should be maintained at a negative pressure within the building (i.e. externally located
exhaust blower).
9. The exhaust blower and duct work should be a sealed system that can hold 2.0 inches (51mm) w.g.
pressure for 30 minutes with no more than a 10% drop in pressure and be properly vented to the
atmosphere to disperse exhausted air.
10. A local manual exhaust flow damper (Nuaire Model NU-940) should be readily accessible (either directly
mounted on the LFBSC exhaust collar or just above the LFBSC) for the maintenance technician/certifier to
allow the LFBSC to be sealed for decontamination purposes. If a Constant Air Volume (CAV) valve is
located above the LFBSC, any exhaust flow adjustments should be made to the CAV valve leaving the
manual exhaust damper in a full open position.
11. It is recommended that the cabinet operation be interlocked with the exhaust blower. Fan relay contacts
are provided for this purpose. However, it is also recommended to have a manual exhaust override
switch near the cabinet for certification and service. For multi-ganged systems, this switch could be used
to interface with a Building Automated System (BAS).
12. It is recommended that when using the NU-951-012 automatic butterfly valve, the system air volume
must remain within ten percent of the given nominal setpoint volume to optimize the measurement and
control performance.
13. It is not recommended to hard connect (i.e. weld) the exhaust connection to the cabinet. This may
damage the exhaust filter and/or the butterfly valve (if present). A silicon sleeve (Nuaire Part No. NU-940-
001), banded between the cabinet's exhaust duct and the plant exhaust duct is recommended, with no
more than a two-inch gap between the ducts, for a 1/8 inch (3mm) thick silicone sleeve. If Nuaire damper
valves are present, see Drawing BCD-05572 for installation.