NuAire Laboratory Equipment

NuAire recently attended the CETA North American conference. The following is a list of changes to NuAire laboratory products.

• New A2 Biosafety Cabinets
  • CellGard ES 475
  • CellGard ES 477
  • CellGard ES 480
• DC Motor/Impeller changes
• Labgard ES 425 Speed Controller Changes
• General Airflow Board / TOUCHLink Biosafety Cabinet Control Board firmware updates
• Pharmagard 797 Isolator Updates

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NU-425 Series 60 and above comes standard with a PSC (AC) motor. The NU-425-300/400/500/600 models can also be purchased with an optional DC-ECM motor. Series 20 and higher field units can also be upgraded with a DC-ECM retrofit kit.

The DC-ECM motor has many features that make it a good choice for customers. This article describes the DC-ECM motor features and how to control it.

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With the introduction of DC motors into NuAire’s Biological Safety Cabinets, procedures for the calibration of airflows have changed on some models. The NU-437’s (A2) new main control board now has the ability to control either an AC or DC motor. With the AC motor you adjust the potentiometer located on the main control board to increase/decrease blower speed. But with the DC motor it requires additional steps to make that adjustment.

The DC-ECM system works like this:

1. AC voltage is applied directly to the DC motor's control module.
2. The motor control module (Microprocessor) converts the AC to DC for internal electronics and to power the motor.
3. In addition, there is a second electrical cable that goes from the Main control board's speed controller output to the motor. This generates a pulse-width-modulation (PWM) 2.5-8 vDC control signal and returns an RPM feedback signal from the motor to the speed controller.

Down-Flow Calibration (60+/-5 LFPM)

1. Place an airflow velocity meter in the cabinet's work-zone and spot check several points on the recommended down-flow test grid.
2. Enter the Airflow calibration mode:
   1. Press and hold the "Alarm Silence Key".
   2. Press FL light ON, light OFF and release the Alarm Silence key.
   3. The Outlet LED should blink and the blower will turn on.
   4. To increase the unit's airflow, press the "UV Key"; to decrease the airflow, press the fluorescent Light "ON" key. (This will change the PWM vDC signal to the motor).
   5. To exit calibration, press the "Alarm Silence Key" again.

Calibration Tips:

• While in airflow calibration mode, you can return to the original PWM signal (2.5 - 8 vDC) setting. Press and hold both the "FL Light ON" and the "FL Light OFF" keys simultaneously for 3 seconds.
• Once the down-flows have been calibrated, you may move onto calibrate the in-flows.

Inflow Calibration (105+/-5 LFPM)

1. If the measured inflow is less than 100 LFPM, adjust the internal choke. If the airflow is still insufficient, increase the PWM signal/VDC.
2. If the measured inflow is greater than 110 LPFM, first adjust the PWM signal/VDC to achieve 1/2 of the excess airflow. Then adjust the choke to balance the airflow.
3. Once the inflow adjustment is complete; return to the down-flow calibration, check average down-flow velocity and adjust as necessary.

Flowgard Calibration

Once the airflow calibration is complete, calibrate the Flowgard airflow monitor:

1. Press and hold the "up and down" arrow keys simultaneously for 3 seconds until the center LED blinks.
2. Allow the unit to run for a minimum of 2 minutes.
3. Press Reset key to enter the nominal airflow value; the Green LED will stop blinking and display normally.

This sets the high/low alarm limits +/- 0.13 w.g. from nominal.

Reference the operating manual for your Labgard 437 for more in-depth information and calibration procedures. If you require help, or have questions, please contact NuAire's technical support department.

DC-ECM (Direct Current-Electronically Commutated Motor) Motors are now being installed in newly manufactured NuAire Class II, Type A2 Biological Safety Cabinets (Labgard NU-437/E/G, Labgard NU-440/E/G, and the CellGard NU-480/E/G). These DC-ECM motors are also available as an option for the Labgard NU-425/E/G product.

NuAire is steadily phasing DC-ECM motors into most of our product lines. The DC motors have proven to be reliable, quiet, energy efficient, and generate less heat/vibration than AC motors. Please review the attached document that describes the DC-ECM motor characteristics, features and benefits.

In addition, older model NU-425's (Series 20 and newer (1995+) ) can be retrofitted with the new DC-ECM motors. The Retrofit kits are RF515, RF516, and RF517. These kits are supported by technical bulletin STB0187. Contact your local Biological Safety Cabinet certifier or NuAire to discuss options for upgrading your existing Labgard 425 Class II, Type A2 biosafety cabinet.

This new system, plus many other features, including the Touchlink Control Center, are part of NuAire's Certifier training class curriculum. Be sure to sign up for one of the classes scheduled soon.

NuAire has produced a new data plate for its biological safety cabinets that conforms to the NSF/ANSI Standard 49-2008 format. Reference NuAire technical bulletin STB0139 for a detailed description of data plate information.

The data plate includes, but is not limited to the following information:

• Manufacturer
• Model Number
• Unit Serial Number
• Series Number
• Class/Type
• Electrical Data
• Window Type/Opening Size
• Nominal Set Points/Method
  • Inflow
  • Downflow
• Downflow velocity test grid
• Secondary Inflow Method/Grid
  • Correction Factor
  • Setpoint

Note: The 3 inch constricted method is the alternate means of measuring inflows for most NuAire biosafety cabinets. (See STB0115).

Contact NuAire's technical service department for additional information.