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WhisperFlow
WhisperFlow™ Laminar Fan/Filter Units (FFUs)

Fan / Filter Unit
Fan/Filter Unit

cULus logo Wafer/CE

Models below are UL and UL-Canadian listed. CE marked models available; inquire when ordering

 
  • Internal baffling plates and anodized aluminum diffuser panel provide uniform air speed across the filter face, ensuring laminar airflow
  • Low-profile design allows cleanroom installation inside rooms with standard 9-foot (2743 mm) ceilings
  • Quiet, low-vibration design: only 50 dBA, measured 30" (762 mm) from filter face @ 90 FPM (0.5 m/s)
  • Provides an average airflow velocity of 90+ feet per minute (0.45+ m/sec) and airflow of 640+ CFM (1088 m³/hr) under filter load at 100% medium setting (2' x 4', 610 mm x 1219 mm, model)
  • Three-setting switch simplifies air balancing (see below for EnergySaver Remote Control System)
  • Meets IEST Recommended Practices
  • Refer to the Application Guidelines for recommendations on quantities to meet specified requirements for cleanliness and lighting.

These reliable, self-powered Fan/Filter Units provide a uniform flow of microfiltered air to meet cleanliness standards down to Class 10 (ISO 4).

All models use a 3-setting (hi/med/lo), centrifugal-type fan/motor with permanently lubricated bearings mounted inside a white powder-coated steel housing with drop-in prefilter (stainless steel available).

Advanced baffling technology ensures uniform airflow across the filter face and attenuates sound. Select HEPA (High-Efficiency Particulate Air) filters, rated 99.99% efficient at removing particles ≥ 0.3 microns, or ULPA (Ultra-Low Penetration Air) filters, rated 99.999% efficient at removing particles ≥ 0.12 microns. They provide years of no-maintenance, 24/7 operation, depending on your air quality.

Housing is powder-coated CR steel; 304 stainless steel housing is available.

WARNING:
Test the Airflow Uniformity
of Your Fan/Filter Units!

Airflow uniformity is critical for applications requiring adherence to ISO, FDA or cGMP cleanliness requirements. More . . .
Automated FFU control systems help meet FDA and other compliance regulations. Add options including environmental monitoring and data logging. Click for details
 
Note: All prices below include installation on a specified Terra modular cleanroom.

Ordering Charts: Click prices to configure and add to cart

Powder-Coated CR Steel Fan/Filter Units

Fan / Filter Units with HEPA Filter
Model Nominal
Dimensions*
Inches
(mm)
Wt.
Lbs.
(Kg)
Avg.
CFM
@ MS
(m3/h)
Airflow ft/min(m/s) Run Amps (Watts)
@ 60Hz
Power With HEPA Filter
HS MS LS HS MS LS Cat. # Price
2 x 4 23.63 x 47.63 x 13
(600 x 1210 x 332)
71
(32)
717
(1218)
115
(.58)
102
(.51)
93
(.47)
4.3A
(512W)
3.5A
(416W)
3.3A
(393W)
120VAC, 60 Hz 6601-24-H $ 677
220VAC, 60 Hz 6601-24-H-220 $ 787
2 x 3 23.63 x 35.63 x 13
(600 x 905 x 332)
53
(24)
602
(1023)
121
(.61)
116
(.59)
106
(.54)
4.1A
(500W)
3.1A
(378W)
2.7A
(329W)
120VAC, 60 Hz 6601-23-H $ 677
220VAC, 60 Hz 6601-23-H-220 $ 787
2 x 2 23.63 x 23.63 x 13
(600 x 600 x 332)
44
(20)
558
(948)
172
(.87)
166
(.84)
162
(.82)
3.9A
(472W)
2.8A
(339W)
2.4A
(290W)
120VAC, 60 Hz 6601-22-H $ 677
220VAC, 60 Hz 6601-22-H-220 $ 787
* With pre-filter installed. Nominal height of CE-marked units is 13.5" (343 mm).
Fan / Filter Units with ULPA Filter
Model Nominal
Dimensions*
Inches
(mm)
Wt.
Lbs.
(Kg)
Avg.
CFM
@ MS
(m3/h)
Airflow ft/min(m/s) Run Amps (Watts)
@ 60Hz
Power With ULPA Filter
HS MS LS HS MS LS Cat. # Price
2 x 4 23.63 x 47.63 x 13
(600 x 1210 x 332)
71
(32)
717
(1218)
115
(.58)
102
(.51)
93
(.47)
4.3A
(512W)
3.5A
(416W)
3.3A
(393W)
120VAC, 60 Hz 6601-24-U $ 787
220VAC, 60 Hz 6601-24-U-220 $ 898
2 x 3 23.63 x 35.63 x 13
(600 x 905 x 332)
53
(24)
602
(1023)
121
(.61)
116
(.59)
106
(.54)
4.1A
(500W)
3.1A
(378W)
2.7A
(329W)
120VAC, 60 Hz 6601-23-U Price
220VAC, 60 Hz 6601-23-U-220 Price
2 x 2 23.63 x 23.63 x 13
(600 x 600 x 332)
44
(20)
558
(948)
172
(.87)
166
(.84)
162
(.82)
3.9A
(472W)
2.8A
(339W)
2.4A
(290W)
120VAC, 60 Hz 6601-22-U Price
220VAC, 60 Hz 6601-22-U-220 Price
* With pre-filter installed. Nominal height of CE-marked units is 13.5" (343 mm).

304 Stainless Steel Fan/Filter Units

(Models below include 304 stainless steel housing, filter frame, and protective grille for easy cleaning with alcohol and other cleaning agents; see charts above for performance data)
304 Stainless Steel Fan/Filter Units
Model Nominal
Dimensions*
Inches
(mm)
Wt.
Lbs.
(Kg)
Power With HEPA Filter With ULPA Filter
Cat. # Price Cat. # Price
2 x 4 23.63 x 47.63 x 13
(600 x 1210 x 332)
71 (32) 120VAC, 60 Hz 6601-24-HS Price 6601-24-US Price
220VAC, 60 Hz 6601-24-HS-220 Price 6601-24-US-220 Price
2 x 3 23.63 x 35.63 x 13
(600 x 905 x 332)
53 (24) 120VAC, 60 Hz 6601-23-HS Price 6601-23-US Price
220VAC, 60 Hz 6601-23-HS-220 Price 6601-23-US-220 Price
2 x 2 23.63 x 23.63 x 13
(600 x 600 x 332)
44 (20) 120VAC, 60 Hz 6601-22-HS Price 6601-22-US Price
220VAC, 60 Hz 6601-22-HS-220 Price 6601-22-US-220 Price

FFU Accessories

Filter Replacement Alarm System

This optional module monitors the efficiency of the HEPA filters and alerts personnel when the HEPA filters need to be replaced.  The module's Photohelic gauge connects to the nearest Fan/Filter Unit equipped with a Challenge Port (Part # 6601-99) and displays the backpressure created within the FFU.

Filter Replacement Alarm System

As the HEPA filter accumulates particles over its lifetime, pressure builds in the space between the blower and the HEPA filter.  The Photohelic gauge features two manually adjustable needles that are used to mark the original backpressure reading and the maximum acceptable level (which is typically double the backpressure reading of a new filter). When the backpressure exceeds this set limit, the LED indicator light located above the gauge will flash, notifying personnel that the room's HEPA filters should be replaced.

If a HEPA filter accumulates too many particles and becomes clogged, it can result in a loss of efficiency that can compromise the cleanroom's ISO rating.  If they are not replaced in a timely manner, severely clogged filters can destroy the motors in the Fan/Filter Units and potentially pose a fire hazard in the event of catastrophic electrical failure.

  Cat. # Price
Filter Replacement Alarm System 2625-54 Price

FFU Challenge Port

Air filters keep your environment clean, but validating their integrity can be cumbersome and knowing when to replace them is a challenge. Room designs, applications and staffing make each cleanroom unique. Therefore, it’s important to get baseline measurements of your equipment when first installed, and then set up a schedule for regular monitoring.

Tubing fits into both the orange challenge port valve and the Magnehelic® gauge to easily record FFU pressure differential.
Upgrade your fan/filter unit (FFU) to include a Terra-installed Challenge Port that both simplifies leak testing and helps establish a filter replacement schedule. The port is 3/8"-diameter, nickel-plated brass adapter fitting with a white polypropylene plug.

Learn more about Terra's FFU Challenge Port.

Price includes installation on specified FFUs.

FFU Challenge Port
Cat. # Price
6601-99 Price

Replacement Filters
Terra FFU Replacement Filters
Type Filter Size / Feet (mm) Cat. # Price
HEPA 2 x 2 (610 x 610) 6601-27 Price
2 x 3 (610 x 914) 6601-26 Price
2 x 4 (610 x 1219) 6601-25 Price
ULPA 2 x 2 (610 x 610) 6601-30 Price
2 x 3 (610 x 914) 6601-29 Price
2 x 4 (610 x 1219) 6601-28 Price

Night Service Switch
  • Energy-saving mode saves 25% of fan operating costs by reducing power consumption during off-hours
  • Maintains round-the-clock cleanroom integrity at lower cost
  • Easy to activate via panel-mounted switch (Wireless Cleanroom Control System also available)

Why Pay More for Less?
Terra cleanrooms are designed to meet a specified ISO cleanliness rating when a cleanroom is in use: with operations in progress, process machinery humming, and personnel in motion. So why pay to maintain that level of FFU performance when a production shift ends and people, the greatest source of contamination, leave the room?

With a greatly reduced contaminant load, a cleanroom at rest maintains its target ISO cleanliness standard with much less airflow, fewer air changes—and decreased power consumption. Terra’s Night Service Switch provides this cleanliness at a nominal cost, giving you immediate cost savings.

Simply select the “Night Service” Switch when you turn off the lights and go home. A separate operation circuit drops all Fan/Filter Units (FFUs) into low-energy operation mode, shaving 25% of energy costs off your power bill while maintaining uninterrupted cleanroom performance at your specified cleanliness level. With Terra's Night Service Switch, operators can save up to 7,000 kilowatt-hours per year with a return on investment in slightly over a year.**
Ordering Information
A complete system includes fan/filter units and Terra's standard Power Distribution Modules (order separately), in addition to the units specified below. The Night Service Switch includes electronic configuration of each FFU controlled by this system. The Control Panel includes switch settings and indicator lights for Normal Mode and Night Service Mode, as well as a tamper-resistant master FFU Off switch.
Night Service Switch
Order one per Fan Filter Unit Cat. # Price
120VAC, 60Hz 6601-70 Price
Control Panel for Night Service Switch
Order one per cleanroom 120VAC, 60Hz 220VAC, 60Hz
Cat. # Price Cat. # Price
Hardwall Cleanroom, External Mount Panels 6600-23-NS Price 6600-23-NS-220 Price
Hardwall Cleanroom, Internal Mount Panels 6600-24-NS Price 6600-24-NS-220 Price
Softwall Cleanroom 6600-25-NS Price 6600-25-NS-220 Price
BioSafe All-Steel Cleanroom 6600-26-NS Price 6600-26-NS-220 Price
BioSafe FRP/C-PVC Cleanroom 6600-57-NS Price 6600-57-NS-220 Price
Comparative Specifications:
2’ x 4’ (600 x 1210 mm) Terra Fan/Filter Unit No. 6601-24-H, operating at High, Medium, and Night Service setting
Operation Setting: High Speed* Medium Speed* Night Service
Airflow: cfm (m^3/hr) 808 (1373) 717 (1218) 654 CFM (1111)
Air Speed: ft/m (m/s) 115 (0.58) 102 (0.51) 93 ft/min (0.47)
Run Amps (Watts): 4.3 (512) 3.5 (416) 3.3A (393W)*
*25% savings over operation on high speed
**Based off of an average-sized cleanroom with 10 FFUs, active cleanroom usage of 8 hours per day, and the U.S. Energy Information Administration's given average retail price of electricity at 10.72 cents per kilowatt-hour.

IonBar™ Ionizing Bar with FFU Installation Kit
Ionizing Bar
Eliminates surface charges generated by laminar flow for a cleaner cleanroom
The IonBar™ generates a balanced stream of positive and negative ions to neutralize surface static charges, protecting sensitive parts against ESD and eliminating surface attractions that make cleaning difficult. Its low-voltage design is intrinsically safe and minimizes EMI/RFI. Includes installation kit for easy attachment to fan/filter units (order separately), which disseminate ions throughout the cleanroom.

For FFU Size
Feet, No. of emitters
(mm)
For 120VAC,
60Hz
For 220VAC,
50/60 Hz
Cat. # Price Cat. # Price
2 x 4, 8
(610 x 1219)
2005-49 Price 2005-49-220 Price
2 x 3, 6
(610 x 914)
2005-48 Price 2005-48-220 Price
2 x 2, 4
(610 x 610)
2005-47 Price 2005-47-220 Price

Cord Adapter
4pin Cord Adapter for FFUs
Connect your Terra Fan/Filter Unit directly to a wall outlet using this 3-foot cord adapter. FFUs are built with a 4-pin electrical connector for integration with a power module in a modular cleanroom or laminar flow hood. This adapter allows you to bridge the power connection when a power module is not used. Simply plug the 4-pin connector, that terminates in a NEMA 5-15 plug for connection, into the FFU power cord and fit the other end into a standard power outlet.

  Cat. # Price
Cord Adapter (4-pin) 120VAC, 60Hz 6601-13 Price

Ceiling-Module Mounting Frame
Stainless steel mounting frames allow ceiling modules to be installed in drywall or other hard ceilings without a ceiling grid.* The frames are sized to hold 2' x 4' fan/filter units or light panels, or 2' x 3' and 2' x 2' fan/filter.

Frames "cradle" the modules, and sit securely in the ceiling cut-out with support from top flange. Continuous seams in the 304 stainless steel frames' corners reduce deposit of contaminating particles and simplify cleaning.
FFU Mounting Frame
FFU Mounting Frame FFU Mounting Frame
Shown with Fan/Filter Unit installed, viewed from above ceiling panel. Ceiling module mounting frame:
2' x 4' shown, holding fan/filter
unit or light panel.
Description Cat. # Price
Mounting Frame: 2' x 4' 6604-02 Price
Mounting Frame: 2' x 3' 6604-01 Price
Mounting Frame: 2' x 2' 6604-00 Price
* Intended for use with supported ceilings that can safely bear the weight of fan/filter unit or light being installed. Mounting frame provides no support beyond the perimeter of the ceiling cut-out.
Specifications
Dimensions: See Replacement Filter chart
Housing: Plenum is cold rolled steel finished with white powder baked enamel. Compatible with 1-1/2" (38 mm) grid on 24" x 48" (610 mm x 1219 mm) centers or 2" (51 mm) grid on 24.5" x 48.5" (622 mm x 1232 mm) centers. 304 stainless steel is available
HEPA Filter: HEPA filter is 99.99% efficient on removal of particles 0.3 microns and larger by DOP (dioctyl phthalate) test. Filter module must be removed from the ceiling for HEPA filter replacement
Prefilter: 20" x 20" x 1" (508 mm x 508 mm x 25 mm)– UL classified for Class 1; rated 80% efficient on linty dusts
Blower: Forward curved centrifugal type factory balanced. Entire motor/blower assembly is removable from top of housing for service
Motor: 1/4 HP Direct drive, energy efficient. Permanent split capacitor type. Thermally protected with automatic overload reset
Electrical: 3-setting motor switch (lo-med-hi). Motor leads are wired to a cable with Mencom 4-pin connector for field connection to Terra cleanrooms and hoods; specify other required power cable
Face Grille: Face grille perforated anodized aluminum
Noise Level: 50 dBA
Weight: See ordering charts
Support: 1/4" (6 mm) eyebolts are installed in all (4) corners for hangwire support

Did You Know?
Fan/Filter Units Do More Than Meet ISO Requirements—
they also prevent infection.

germ on carpet  

Most cleanroom professionals understand that FFUs capture contaminants that degrade particle-sensitive samples. But they also remove bacteria and many viruses and mold spores that contribute to a host of infections.

Most common bacteria are contained by the 0.3-micron pore size of high-efficiency particular air (HEPA) filters. Ultra-Low Penetration Air (ULPA) filters, which are rated 99.999% efficient at retaining particles of 0.12 microns and larger in diameter, capture ultra-fine contaminants, including many large viruses and mold spores.

These filters also remove aerosol-born pathogens—germs that literally hitch a ride on larger particles and liquid droplets that are captured in a HEPA or ULPA filter.

HEPA- or ULPA-based Fan/Filter Units (FFUs) thus can play an important in infection prevention in surgical theaters, ICUs and other medical settings. Here is a list of common human pathogens that HEPA/ULPA filters capture and remove from circulation:

Pathogens: Bacteria   Disease
Escherichia coli   Gastrointestinal infection
Bacillus anthracis   Anthrax
Aspergillus brasiliensis   Sinus infections
Francisella tularensis   Tularemia
Bordetella pertusis   Whooping cough
Mycoplasma pneumaoniae   Pneumonia
Chlamydia pneumoniae   Bronchitis
Clamydia psittaci   Psittacosis
Klebsiella pneumoniae   Opportunistic infections
Haemophilus influenzae   Meningitis
Coxiella burnetii   Q fever
Pseudomonas aeruginosa   Opportunistic infections
Actinomyces israelii   Actinomycosis
Legionella pneumophila   Legionaire's disease
Thermoactinomyces sacchari   Farmer's lung
Bacterium alkaligenes   Opportunistic infections
Streptococcus pyogenes   Scarlet fever
Mycobacterium Tuberculosis   Tuberculosis

 

WARNING:
Don't underestimate the importance of uniform airflow!

ISO, FDA or cGMP laminar flow requirements necessitate uniform airflow velocity across the filter face of fan/filter units (FFUs). Many FFUs that appear to meet nominal cleanliness requirements fail to provide this uniformity, threatening the integrity of your clean processes.

What is airflow uniformity?
Certifiers measure air velocity at multiple (typically six or eight) locations across a filter face. Ideally, air speed measurements taken at these locations vary by no more than 15% from mean values. For example, in an ISO 5 laminar flow system with a specified minimum average air velocity of 90 fpm (feet per minute), the minimum air speed measurements typically should be in the range of 80 – 100 fpm.

Discrepancies greater than this create turbulence as the faster air streams (lamina) are drawn into the localized areas of lower pressure created by the slower ones.

The greater the airspeed differential, the more likely and the more severe this turbulence becomes, resulting in swirling that can suspend minute particles rather than sweeping them downward and out of the laminar flow system. Worse, localized turbulence can create second-pass air that swirls up and re-enters the downward flow, drawing particles upward and redistributing them into other locations inside the classified work space. Under such conditions, a cleanroom or laminar flow cabinet fails to meet ISO laminar flow conditions – and ceases to be a clean!

How does airflow uniformity differ from airflow average?
Some FFU manufacturers specify an average airflow (or average velocity) that can mask serious performance deficiencies.

In the case below, a Fan/Filter Unit produces an average airflow of 1004 CFM (cubic feet per minute) and average air speed of 125 fpm on high speed, perfectly acceptable performance values. However, individual lamina measurements demonstrate substantially non-uniform filter face velocity and flow, with discrepancies of over 60% at various locations across the filter (30% from mean values). FFU performance will create areas of turbulence due to this lack of uniformity.

turbulent zone illustration Turbulent zone created
by non-uniform velocity (characterization of air velocity performance, in feet/minute)

How does a Fan/Filter Unit achieve airflow uniformity?
Several design and construction features help to ensure uniform FFU performance in Terra-manufactured FFUs. Most importantly, these FFUs include an internal baffling system and plenum chamber that equalize the air pressure across the filter face as the air exits the motorized impeller. Uniform inlet pressure correlates to uniform exit velocity, assuming a high-quality filter medium of uniform density and flow resistance.

In addition, Terra FFUs include a perforated anodized aluminum exit plate that both protects the filter medium against damage and helps to reinforce even air distribution across the filter face.

Finally, sound-deadening foam contributes to the rigidity of the structure while dampening noise and vibration, resulting in whisper-quiet operation that won’t interfere with operator health or productivity.

Although these measures add to the manufacturing cost of Terra FFUs, they contribute substantially to their performance (see comparative data below).


Turbulent Performance: Fan/Filter Unit with non-uniform airflow
Measurements of non-baffled 2' x 4' HEPA Fan/Filter Unit with AC impellerized motor, taken 6" from filter face (source: measurements taken on Terra competitor 2' x 4' FFU)
Speed Setting: High
Noise: 73 dBA
Average Speed: 125.5 fpm
Average Flow: 1004 cfm
Max. Deviation from Mean: 27.5%
High Speed
Top Right:
157 fpm
Top Center:
95 fpm
Top Right:
122 fpm
Bottom Left:
160 fpm
Bottom Center:
109 fpm
Bottom Right:
110 fpm

Medium Speed
Top Right:
58 fpm
Top Center:
47 fpm
Top Right:
53 fpm
Bottom Left:
61 fpm
Bottom Center:
39 fpm
Bottom Right:
34 fpm
Speed Setting: Medium
Noise: 60 dBA
Average Speed: 48.7 fpm
Average Flow: 389 cfm
Max. Deviation from Mean: 30%

Speed Setting: Low
Noise: 55 dBA
Average Speed: 7.6 fpm
Average Flow: 61 cfm
Max. Deviation from Mean: Out of Spec
Low Speed
Top Right:
0 fpm
Top Center:
0 fpm
Top Right:
0 fpm
Bottom Left:
46 fpm
Bottom Center:
0 fpm
Bottom Right:
0 fpm

Laminar Performance: Terra Fan/Filter Unit with uniform airflow
Measurements Terra’s 2' x 4' HEPA Fan/Filter Unit (No. 6601-24-H) with AC impellerized motor, taken 6" from filter face
Speed Setting: High
Noise: 55 dBA
Average Speed: 139 fpm
Average Flow: 980 cfm
Max. Deviation from Mean: 13%
High Speed
Top Right:
150 fpm
Top Center:
125 fpm
Top Right:
149 fpm
Bottom Left:
137 fpm
Bottom Center:
121 fpm
Bottom Right:
154 fpm

Medium Speed
Top Right:
131 fpm
Top Center:
120 fpm
Top Right:
111 fpm
Bottom Left:
121 fpm
Bottom Center:
108 fpm
Bottom Right:
112 fpm
Speed Setting: Medium
Noise: 54 dBA
Average Speed: 117 fpm
Average Flow: 823 cfm
Max. Deviation from Mean: 12%

Speed Setting: Low
Noise: 53 dBA
Average Speed: 100 fpm
Average Flow: 703 cfm
Max. Deviation from Mean: 5%
Low Speed
Top Right:
105 fpm
Top Center:
96 fpm
Top Right:
103 fpm
Bottom Left:
98 fpm
Bottom Center:
96 fpm
Bottom Right:
105 fpm

File Type File Name Publication Date
White Paper (PDF) Airflow Uniformity and Fan Filter Units
Fan filter units help to remove contaminants from controlled environments. They are effective if designed well. Variables like speed and baffles contribute to an FFU's ability to maintain uniform air speed and direction. Read more about how FFUs help you comply with ISO and other regulations.
05/28/2015
Tech Resource (PDF) HEPA and ULPA Particle Filters
HEPA and ULPA filters remove sub-micron particles from the air, which are too small to see but create BIG problems in many critical manufacturing operations. Read about filter capability and airflow resistance testing.
05/18/2015
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