Performance qualification (PQ)
7.0 General Maintenance
CAUTION: All maintenance actions on this equipment must be performed by a qualified technician who is familiar with the proper maintenance procedures required for this equipment. This includes both certification as well as repair.
7.1 Decontamination
No maintenance should be performed on the interior of the Labgard cabinet (area behind access panels) unless the cabinet has been microbiologically decontaminated, is known to biologically clean, or known to be chemically inert. Surface disinfection is performed as specified in the cleaning procedures.
If microbiological decontamination is necessary, use the following procedure:
1. Remove screws at each upper side of the control center and allow the control center to rotate down, resting on the safety straps. Remove control center by disconnecting safety straps and moving control center to the left off the slip hinges.
2. Remove the front decorative panel via top/front fasteners.
3. Remove left and right window farings via fasteners.
4. Remove armrest via fasteners.
5. Place decontamination equipment inside the work area. Reference decontamination procedure, per NSF Standard 49, Annex G, using the following chart to calculate chemical requirements.
Note: The outlets in the work area are energized as long as the cabinet is plugged in and switched on the front panel. Unplug the cabinet before decontamination equipment is plugged into these outlets or run the decontamination power cords under the front seal area.
6. Use duct tape and plastic to seal the front and exhaust area.
CAUTION: BE SURE CABINET IS TOTALLY SEALED TO PREVENT ANY LABORATORY EXPOSURE TO DECONTAMINATION GAS.
7. Perform decontamination procedure per NSF Standard 49, Annex G.
If the cabinet has been used to prepare hazardous drugs, (chemotherapy), or other toxic chemicals, decontamination of the cabinet cannot be accomplished by the above procedure. (See section 6.6 for guidelines)
Please consult with NuAire, Inc. about any unique contamination problems.
Normally, no preventive maintenance is required on the interior of the cabinet (i.e., the area behind the access panel containing the HEPA filters and motor (blower assembly). All required adjustments in order to maintain proper cabinet airflows are external to the cabinet interior. The motor is lubricated for life and is thermally protected with automatic reset.
7.2 Fluorescent Lamp Bulb Replacement
The two (T8) fluorescent bulbs are cool white, rapid start and placed external to the cabinet to aid maintenance and minimize heat build-up within the cabinet. The life rating of the bulb is 9000 hours based on three-hour burning cycles.
To replace a bulb, it is necessary to remove the lamp assembly.
1. First, switch Cabinet Light Switch off.
2. Second, remove the screws at each upper side of the Control Center and allow the Control Center to rotate down, resting on the safety straps.
3. The bulb is now directly exposed for replacement.
4. The bulb is removed by displacing the bulb to one side against the compressible bulb holder and lifting out the bulb.
5. Reverse the procedure to reinstall the lamp assembly being careful not to pinch the safety straps, cable or tubing during closure of the control center.
7.3 HEPA Filter/Motor Replacement (Drawing BCD-05153)
The HEPA Filters under normal usage and barring an accident (a puncture), do not need replacement until the efflux velocity cannot be maintained or the access inflow velocity cannot be maintained at 80 LFPM (.80 m/s)(min.). This may permit the average downflow velocity to be as low as 70 LFPM (.35 m/s) as long as no point falls below 64 LFPM (.32 m/s)
The HEPA Filters should not be replaced until the entire cabinet has been decontaminated or known to be biologically "clean".
7.3.1) Procedure (see Drawing BCD-05153)
CAUTION: Disconnect electrical power from the unit before attempting any maintenance action.
Step 1: Remove screws at each upper side of the control center and allow the control center to rotate down, resting on the safety straps. Second, remove the front decorative panel which is held into position by (3) knurled nuts on the top edge and (6) knurled screws on the front.
Step 2: Place sliding window into lowest position and remove front filter panel, which is held into position by Phillip pan head screws. Once the screws are removed, the panel is held into position by smooth weldstuds located on the top corner of the front filter panel. Use the window stop brackets as handles to remove the panel.
CAUTION: Screws are used in lieu of acorn nuts, and lockwashers. The screws have O-rings and should be replaced if damaged or badly deformed.
The interior of the cabinet is now fully exposed for replacement of the filters and/or motor/blower.
Step 3: Filter Removal
It is not always necessary to replace both the supply and exhaust filters at the same time. If during the course of certifications, the downflow falls off while the exhaust increases (i.e. greater than 110 LFPM) (.56 m/s), the supply filter is "loading" faster than the exhaust filter, and only the supply filter may need replacement. The opposite might also happen depending upon many factors.
• To remove the supply filter:
1. First, remove the HEPEX/choke tray band clamp between the supply HEPEX and the exhaust filter choke tray. Separate the plenum from the choke tray.
Note: Double sticky back gasket is used to hold the plenum to the choke tray and should be replaced when reassembling.
2. Remove the 2 supply filter hold-down clips (1 each side) holding the filter down.
3. Remove the HEPEX pressure plenum from the blower assembly. The HEPEX is clamped to the blower assembly via a band clamp.
4. Carefully remove the supply filter and HEPEX. The HEPEX can be folded neatly to seal the contaminated side of the HEPA. Direct exposure should be avoided.
Dispose of spent HEPA filters properly. Avoid direct contact to "dirty side" of the filters. Label all waste containers/cartons based on the type of hazard.
• b. To remove the Exhaust HEPA:
1. Relax the exhaust filter seal loading mechanism by turning the four threaded bolts counterclockwise until one can see a definite release of the loading springs.
2. Pull the exhaust choke tray free and remove the filter. It is not necessary to remove the tray, although it is free to move forward several inches, if necessary, to free the HEPA filter.
Step 4: Filter Installation
WHEN INSTALLING NEW FILTERS, USE ONLY FILTERS OF THE SAME RATED FLOW AND SIZE AS ORIGINALLY INSTALLED. It is recommended that a new HEPEX/Supply filter be installed since the HEPEX is factory installed to the filter. However, field installation kits are available separately from the filter.
a. To install the supply filter, simply reverse the procedure outlines in Step 3a, above.
Note: Be sure to open the choke plate fully before inserting the filter into the tray. This will assist in adjusting the airflow.
b. To install the exhaust filter, apply a thin layer of silicone grease to the top and bottom gaskets of the filter and carefully insert into the exhaust choke tray.
Position the filter frame within the outside walls of the exhaust opening on the top of the hood. Tighten the spring loaded bolts, 4 places, depressing the gasket material by 1/8 inch (3mm).
Step 5: Motor/Blower Assembly Removal
Note: Removal and replacement of the motor/blower may best be performed with the supply HEPA filter/HEPEX removed to reduce the chance of damage to the fragile HEPA filter media. Perform step 3.a. and place the supply in a secure location where it will not get damaged.
a. It is recommended that the motor/blower to be removed as a single unit. To remove, disconnect electrical connections to the motor, remove the HEPEX pressure plenum and unbolt the motor/blower assembly from the roof of the cabinet (4 places). Always inspect the rubber isolation motor mounts and replace those that are cracked or visibly show stress.
b. Replace the motor exactly as originally installed in the blower housing, paying particular attention to the correct electrical connections (see Electrical Schematic).
c. Re-install the new motor/blower assembly
7.4 Sliding Window Replacement & Adjustment
The sliding window replacement is accomplished by removing the front decorative panel, control center and window glide assemblies. The sliding window adjustment may be required due to everyday use over the life of the cabinet. The left window glide is stationary since it contains the microswitches that monitor window height. The right window glide is adjustable by a set screw and tension screw method (see Drawing BCD-11818). When adjusting the sliding window, be sure to verify proper microswitch operation. If the sliding window is too loose, the sliding window will not properly activate the microswitches, thus causing potential operational malfunctions to occur.
7.5 Airflow Calibration
The NU-425 Airflow Calibration Consists of adjustments to balance the airflow within the cabinet. THIS WORK SHOULD BE DONE ONLY BY A QUALIFIED TECHNICIAN WHO CAN MEASURE THE AIRFLOW FROM THE FILTERS WITH A SUITABLE VELOMETER. NuAire provides two adjustments to balance the airflow within the cabinet. These are:
a. PWM signal adjustment via DC motor speed control
b. Exhaust filter choke
The PWM signal adjustment establishes the motor speed controls curve starting point of the programmed internal reference performance curve while the choke adjusts or balances the exhaust airflow as well as makes up for filter resistance tolerances. Since it has been NuAire's experience that the filters may not "load" evenly, choke adjustments may be necessary for proper cabinet performance.
The cabinet is considered to be certifiable if the following airflow measurements are present:
a. Downflow average: 75 LFPM ± 5 LFPM (.30 m/s ± .025 m/s).
b. Inflow average: 90 LFPM ± 5 LFPM (.46 m/s ± .025 m/s) using the direct inflow measurement method
BEF