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ValuLine™ HEPA Fan/Filter Units (FFUs)
Value without Compromise

ValuLine Fan/Filter Unit
Fan/Filter Unit

cULus logo

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

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 . . .
  • Provide high-volume HEPA-filtered air for cleanrooms, laminar flow benches and other particle-free enclosures
  • Low-profile design allows cleanroom installation inside rooms with standard 9-foot (2743 mm) ceilings
  • Ideal for use in production facilities where noise volume is not a concern (select Terra's WhisperFlow Fan/Filter Unit for critical applications; see specification notes below)
  • Ideal for non-laminar flow applications, with less than 20% ceiling FFU coverage, where non-uniform face velocity poses no problem (see "ValuLine vs. WhisperFlow" technical guide below
  • 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
  • Three-setting switch simplifies air balancing
  • 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 HEPA-Filtered air to meet cleanroom standards.

Its robust, 3-speed centrifugal-type can/motor is designed for years of round-the-clock, trouble-free service. It features permanently lubricated bearings for smooth, low-vibration operation. The CRS steel housing includes a drop-in prefilter to extend the life of the HEPA (High-Efficiency Particulate Air) filter, which is rated 99.99% efficient at removing particles ≥ 0.3 microns.

All models belwo require hard wiring to power source (not provided with cords or plugs).

Ordering Charts: Click prices to configure and add to cart

ValuLine Fan/Filter Unit with HEPA Filter
Nominal Dimensions
Inches (mm)
Airflow ft/min(m/s): Speed With HEPA Filter
High Medium Low Cat. # Price
23.63 x 47.63 x 13
(600 x 1210 x 332)
6601-24-H-VL Call TUI
Avg. CFM @ MS
Run Amps (Watts) @ 60Hz Weight
Lbs. (Kg)
120VAC, 60 Hz

FFU Accessories

ValuLine FFU Replacement HEPA Filter
Filter Size / Feet (mm) Cat. # Price
2 x 4 (610 x 1219) 6601-25 $ 353
Dimensions: See Ordering chart
Housing: Cold-rolled steel finished with anti-finger print coating. Compatible with 1.5" (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
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 x 508 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). No power cord provided (unit must be hard-wired)
Face Grille: Face grille perforated anodized aluminum
Noise Level: 62 dBA (Select Terra's WhisperFlow model for quiet operation)
Weight: See Ordering chart
Support: 0.25" (6 mm) eyebolts are installed in all (4) corners for hangwire support

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 $ 105
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 $ 1,779 6600-23-NS-220 $ 1,779
Hardwall Cleanroom, Internal Mount Panels 6600-24-NS $ 1,779 6600-24-NS-220 $ 1,779
Softwall Cleanroom 6600-25-NS $ 1,663 6600-25-NS-220 $ 1,663
BioSafe All-Steel Cleanroom 6600-26-NS $ 1,779 6600-26-NS-220 $ 1,779
BioSafe FRP/C-PVC Cleanroom 6600-57-NS $ 1,779 6600-57-NS-220 $ 1,779
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
For 120VAC,
For 220VAC,
50/60 Hz
Cat. # Price Cat. # Price
2 x 4, 8
(610 x 1219)
2005-49 $ 681 2005-49-220 $ 689
2 x 3, 6
(610 x 914)
2005-48 $ 595 2005-48-220 $ 605
2 x 2, 4
(610 x 610)
2005-47 $ 497 2005-47-220 $ 525

ValuLine™ vs. WhisperFlow™ Fan Filter Units
All Terra FFUs contain certified HEPA or ULPA filters that provide industry-leading performance to ensure effective control of microcontaminants. The primary differences are sound levels, airflow uniformity, and configuration versatility.

ValuLine FFUs: No-Frills Cleanliness
These models operate at noticeably higher sound levels, but why pay for sound-dampening technology if your FFU enclosure is located in a warehouse or other non-critical environment? ValuLine HEPA FFUs do provide the same filtration efficiency or other HEPA FFUs, and at substantially lower cost.

Air speed across the filter face, however, is not as uniform on ValuLine models as on Terra's premium WhisperFlow FFUs. Due to greater differences in the average air speeds measured across the filter face, these units can result in turbulent zones or airflow lamina that don't meet the unidirectional requirements called for in stringent cleanroom applications (typically, ISO 5 or cleaner).

This performance difference typically does not matter, though, for turbulent-flow (ISO 7 - 9)l applications that simply require micro-filtered air around a contamination-sensitive tool or process.

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

WhisperFlow FFUs: Premium Performance and Versatility
Terra's WhisperFlow Fan Filter Units provide a greater range of configurations, included more sizes and filter types (HEPA and ULPA) as well as room side-replaceable, which allow easier filter maintenance, and reverse flow models. Their housings are cleaner and more chemical resistant, making them suitable for use in a clean environment. They also come in low-energy EC motor configurations that meet strict energy requirements that apply in an increasing number of states and municipalities.

Most importantly, their unique airflow baffle and noise-dampening technology results in much quieter units that maintain industry-leading airflow uniformity across the filter face, optimizing unidirectional airflow suitable for laminar flow workstations and ISO 4-7 cleanrooms.

Standard Features & Configurations ValuLine™ Fan Filter Unit WhisperFlow™ Fan Filter Unit
Sound Level
(2' x 4' model @ high speed)
62 dBa 50 dBa
Airflow Uniformity*
(2' x 4' model)
30% 12%
Housing Material Cold-Rolled Steel Powder-Coated or
Stainless Steel
Sizes Available 2' x 4' 2' x 4', 2' x 3', 2' x 2', 4' x 4'
16" x 2', 16" x 3', 16" x 4'
Filter Type (Efficiency) HEPA (99.99% @ 0.3 µm) HEPA (99.99% @ 0.3 µm)
ULPA (99.999% @ 0.12 µm)
Motor Types AC AC
EC (electrically commutated)
Other Configurations None Reverse Flow
Room-side Replaceable
Explosion Proof
Available Options
Ionizing Bar Yes Yes
Night Service Yes Yes
Automated Control System No Yes
Challenge Port No Yes
* Deviation of mean air speed values measured at medium speed at eight locations across the filter face.
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