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A - Air Flow Design
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B - Wall Panel Material
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B1 - Stainless Steel

Stainless steel is a golden standard among cleanroom construction materials. Easy cleaning, favorable heat properties, and chemical resistance make stainless an ideal choice for biopharmaceutical and semiconductor environments. The smooth surface is easy to wipe down, resists biofilm buildup, and will not off-gas.

B2 - Powder-Coated Steel

Powder-coated steel is an economical choice that also provides favorable heat and chemical resistance for most applications. Terra’s signature white powder coat finish provides a high quality, durable barrier to protect against corrosion, plus a clean and attractive aesthetic. The advanced heat-fused formulation exceeds ASTM and ISO paint standards to resist chipping, scratching, fading, and wearing.

B3 - Acrylic

Acrylic is widely used in cleanrooms and other critical environment applications. Its low initial cost, lightweight, transparency, and tensile strength makes it an attractive choice in many situations. Terra offers economical acrylic enclosures as a budget-friendly option. While acrylic is fairly durable against UV light and impact-resistant, the material is easily degraded by alcohols and solvents.

B4 - Static Dissipative PVC

Static-Dissipative PVC comes in rigid or flexible material for use on hardwall cleanroom panels or cleanroom curtains, dust covers, microenvironments, and other applications requiring a softer material. Non-dissipative plastics quickly accumulate surface charges that attract contaminants. Dissipative plastics prevent static build-up that attracts airborne particulate and lint fibers, which makes surfaces easier to wipe down. Static-dissipative PVC (SD-PVC) will not hold a static charge, offers wide chemical compatibility, and cleans easily. SD-PVC retains a surface resistivity of 10^6 - 10^8 ohms/square indefinitely unlike spray-on coatings that can wear off after a few years. SD-PVC also resists alcohol and most other sterilizing solutions, thus supporting standard disinfecting procedures and extending the life of your enclosure.

B5 - Polycarbonate

Polycarbonate is transparent with a slight gray tint and offers broad-spectrum chemical resistance, high impact resistance, and excellent thermal resistance (to 200°F / 93.3°C). Polycarbonate is stronger and cracks less easily than both acrylic (15x stronger) and glass (250x stronger).

B6 - Polypropylene

Polypropylene is an opaque thermoplastic with excellent chemical resistance against acids and solvents.

B7 - Chlorinated PVC (C-PVC)

Cleanroom chlorinated polyvinyl chloride (C-PVC) wall panels are tested and certified to meet ISO 5 – 8 cleanliness standards. These compressed panels have excellent chemical resistance and prevent particle emission and microbial growth. Their unique solvent-free silicone adhesive allows installation on wallboard substrate creating a strong, rigid structure when mounted to Terra’s steel frame. Welded seams are trim-free, without cracks or gaps. Optional PVC coving is available for floors and corners to further simplify cleaning.

B8 - Fiberglass Reinforced Plastic (FRP)

Class A and C FRP panels feature a unique non-outgassing advanced polymer adhesive for installation on drywall or other substrates. A specialized seam sealant provides trim-free seams that expand and contract to accommodate temperature-induced dimensional changes without creating cracks or gaps. A patented surfacing technology seals panels uniformly to enhance durability and prevent particle emission and microbial growth.

B9 - Tempered Glass

Tempered cleanroom glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempered glass is not only impact resistance, but also ideal for its high visual clarity and aesthetic. Glass wall cleanrooms allow easy monitoring of operators and processes within the cleanroom and tend to appear larger and more spacious. Tempered glass is non-outgassing and chemical-resistant, making it ideal for frequent decontamination.

B10 - Vinyl Curtains

Cleanroom vinyl curtains are lightweight and rapidly installable for creating room partitions, isolating equipment and processes, or mobile isolation when configured with wheel casters. Curtain strips are available in either 4' -wide softwall panels made of blur-free 40 mil vinyl or 8” -wide strip curtains made of blur-free 60 mil vinyl. Static-Dissipative PVC vinyl includes built-in static inhibitors and is recommended for all cleanrooms to minimize particle cling. A T-Grid Mounting System allows suspension of curtains or strip shields from Terra's cleanroom ceiling grid.

B11 - Modesty Panels

Modesty panels provide the combined benefits of natural light while also maintaining a degree of privacy. These panels are ideal for multi-level cleanroom mezzanines that require additional office space or unclassified storage. Modesty panels include an opaque lower panel and upper panel of transparent glass or cleanroom-rated plastic such as polycarbonate or static dissipative PVC. A solid lower panel provides a balance of privacy while the transparent window allows the introduction of natural light and tends to make the space appear larger and less constricted.

B12 - Insulated Panels

A double-wall, insulated wall panel promotes a stable environment for long-term sample storage, cell cultivation, or high-volume process equipment. Terra's double-wall insulated panels are adaptable to the customer’s temperature range specifications and application requirements including cold rooms, incubation, and sound isolation. Double-wall construction with 1”-thick polyurethane insulation enhances cleanroom heating/cooling efficiency and thermal stability. Rigid foam insulation paired with a climate control system provides better temperature stability for applications that require raised flooring for true laminar flow. Double-wall structure allows air to circulate through the inter-wall plenum which further increases filtration and A/C efficiency in high-performance applications.

B13 - Center-Mount Panels With Mirror-Finish Steel Brackets

Most of Terra’s competitors affix the cleanroom wall panels directly to the frame (mounted on the internal or external side of the frame. With this design, replacing cleanroom wall panels is a cumbersome task and requires cleanroom shutdown. If the panels are affixed externally to the frame, installing coved flooring is virtually impossible and the customers are tasked with sterilizing the frame along with all of its crevices. If the panels are mounted internally, the customer loses precious cleanroom space. If the flooring is coved to the internal panels, the customer loses even more space. Terra’s center-mount panel design alleviates these issues.

A – Application: Which Desiccator is Best for My Application?
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Cost vs. Control: Terra Desiccators Simplify Your Choice

You need to protect sensitive samples, but you don’t want to overpay. Below is a list of application descriptions to help choose the best desiccator storage system for your application and budget.

A1 - Critical Control Demands:

For applications that require not only a low-RH set point, but a system that recovers it quickly when doors open/close, allows a different set point in each chamber, and/or protects against static and particulate contaminants.

Typical Applications

• Low exposure tolerance: Microelectronic or pharmaceutical samples that degrade very quickly when exposed to moisture.
• High access frequency: Doors open/close before system can recover target set point level.
• Exposure testing: Requires a separate %RH monitor/control in each desiccator chamber.
• ESD-sensitive parts: Minute static discharge results in severe degradation, cuts yields.
• Sterile and/or Particle Sensitivity: Critical contamination requirements won’t tolerate materials that shed particles or corrode.

A2 - Moderate Control Demands:

Sensitive samples may require automatic low humidity set point control, but low access frequency minimizes the need for faster RH recovery time. Protection against ESD and/or particulate contaminants may also be required.

Typical Applications

• Low-Moderate exposure tolerance: Low humidity and automatic monitoring is required. Microelectronic or pharmaceutical samples that degrade when exposed to moisture.
• Moderate-High Access Frequency: Parts are accessed on a daily basis and/or are sensitive to moisture exposure when doors are opened.
• ESD-sensitive parts: Minute static discharge results in severe degradation, cuts yields.
• Sterile and/or Particle Sensitivity: Critical contamination requirements won’t tolerate materials that shed particles or corrode.

A3 - Minimal Control Demands:

You need occasional nitrogen purging or desiccant to bring down the RH, or you may only need a dust-free enclosure without humidity control.

Typical Applications

• Moderate-High exposure tolerance: Low humidity and/or automatic monitoring is not required.
• Low Access Frequency/Extended Storage: If low humidity is required, fast recovery time is not, because doors are rarely opened: you stock the sample and come back for it days or weeks later.
• Moderate Static Protection: Availability of static-dissipative materials a plus, but ionization not required.
• Dust-Free Conditions: Samples require a clean environment, but chrome plating and adhesive seals are acceptable.

Additional Application Considerations:

For critical moisture control applications, relative humidity (RH) set-point recovery time is one of the most important considerations to achieving the required quality, safety, and shelf life of stored materials.

RH recovery is the time needed to reach an RH set point after a desiccator chamber or cabinet is accessed. A fast RH recovery time minimizes exposure of stored materials to harmful moisture levels. Thus, the ideal desiccator quickly and efficiently reaches and maintains the desired RH level.

Set-point recovery time depends on several variables listed below. Keep these factors in mind to choose the best desiccator storage system for your application and budget.

• Internal & External RH:

  The desired internal RH set point depends on industry and application. Extremely low humidity requirements (under 10% RH) are more difficult to achieve and generally call for a Smart controller option to optimize recovery time and efficiency.

  The greater the gap between required internal RH and ambient RH, the more time and inert gas will be needed to remove moisture from inside the desiccator. For example, a desiccator in a more humid ambient environment will have more moisture in the air to displace, and will therefore require more nitrogen gas or a more efficient humidity control system than one in a less humid environment.

• Access Frequency & Duration:

  RH set-point recovery time is affected by the need to access parts inside the desiccator cabinet. Each time a door is opened, moisture-laden air, often bearing particles, enters the exposed chamber. The longer a door is left open, the more ambient air can flow inside. Once the door is closed, depending on the cabinet design, moisture can migrate from chamber to chamber, raising the internal RH throughout the cabinet.

  During periods of frequent or prolonged access, a poorly configured desiccator may never attain the required RH set point, posing a serious threat to quality, safety, or shelf life of stored materials.

  Choosing an appropriate automatic RH control system and cabinet design will help mitigate problems caused by frequent access.

• Desiccator Cabinet Size & Chamber Configuration:

  The size or volume of your desiccator will determine how much ambient air needs to be displaced to reach your target RH set-point. Thus larger desiccators typically require more nitrogen or a more efficient RH control system, than smaller ones.

  Furthermore, the chamber configuration can have a significant effect on time to reach set-point. Isolated chambers tend to be more efficient, as opening one chamber will not expose other chambers in the cabinet to ambient air. Non-isolated chambers that share the same air space will generally take longer to recover after one door is opened, as ambient air can more easily circulate through the entire cabinet.

• Nitrogen Gas Expense:

  Users seek to achieve a low RH set-point as efficiently as possible to reduce wasteful gas consumption. Unfortunately, unassisted RH control systems require significantly higher consumption of nitrogen gas to reach the desired relative humidity set-point. This problem compounds with high access frequency.

  High nitrogen gas consumption drives up overhead cost and can lead to other operational problems. For instance, those who rely on gas canisters will need to plan for more frequent replacements and will be suseptible to dealing with supply shortages.

  A smart control system automates the process to conserve nitrogen and reduces costs by up to 78%. A nitrogen generator can also eliminate the supply shortage issues from dependence on pre-filled gas canisters.

• Cabinet Material Type:

  Material type can also affect relative humidity inside a desiccator cabinet. The more porous or hygroscopic a material, the easier it is for gases and moisture to transfer through. Many plastics such as acrylic may appear impermeable to the naked eye, however are porous enough at a molecular level to absorb moisture that can then permeate into the chamber. The diffusion or passage of moisture through acrylic can occur in a few ways listed below. The higher the difference between moisture levels, and the greater the exposed surface area, the higher the rate at which moisture will enter the chamber.

  1. Walls inside the cabinet can absorb moisture from ambient air already inside the cabinet, and then release the moisture after the cabinet is purged with a dry inert gas.
  2. Moisture can permeate through the walls from the outside (higher moisture) to inside (lower moisture).
  3. Walls can absorb moisture from direct contact with water (either inside or outside the cabinet).

  Critical moisture control applications concerned with moisture vapor transmission rate (MVTR) should consider a vapor impermeable cabinet material such as stainless steel to achieve the required quality, safety, and shelf life.

B – Nitrogen RH Control Systems:
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B1 – Nitroplex™ System

NitroPlex™, Terra’s most efficient humidity control solution, is designed for the most demanding critical moisture control applications. The system features multiple RH sensors modules to allow RH monitor & control to 0% RH in each isolated chamber. The modules use automatic binary (on/off) valves to quickly and efficiently direct N2 gas where and when it’s needed. The ability to establish separate humidity set points in each storage chamber allows for storage of parts with differing moisture sensitivities and conservation of N2 gas in chambers that are not in use.

B2 – IsoDry® System

IsoDry® upgrades the Dual Purge™ & NitroWatch™ system by adding twin dilution fans for drastically improved RH recovery & uniformity. The fans rapidly mix and circulate incoming nitrogen gas to accelerate moisture removal and achieve uniform RH throughout the entire cabinet. The door sensors de-activate the dilution fans when a door is open to minimize the spread of incoming moisture and contaminants throughout the cabinet.

B3 – Dual Purge™ & NitroWatch™

This system is designed for larger cabinets. Like the Smart® system, it features a single RH sensor for automatic RH set point control to 0%RH. The Dual Purge™ has two gas flow settings (high/low) to rapidly reach and then maintain the user-specified set-point. Door sensors trigger high gas flow when doors open to help protect against the entry of contaminants, and expedite set-point recovery. Because this system includes only 1 RH sensor, the displayed RH reading may not accurately reflect the RH in other chambers of the cabinet.

B4 – Smart® System

Terra’s Smart® desiccator system features a built-in RH Sensor to provide automatic RH set point control to 0% RH with binary (on/off) gas flow. The automatic RH set point control minimizes necessary supervision and increases efficiency of N2 gas consumption. The system is recommended for smaller cabinets with 1-2 chambers. This single gas inlet system can encounter inefficiencies with gas distribution and RH uniformity in larger cabinet systems.

B5 – Flow Meter

A manually controlled flow meter offers the lowest up-front cost for RH control. It is most suitable for smaller desiccators that do not require much nitrogen gas or those that require minimal supervision. Manual control means humidity control is more prone to human error and not as efficient with the consumption of inert gas, which can lead to damaged products and high operating costs.

A - Humidity/Moisture Control
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A1 - High Humidity (Above Ambient to 95% RH)

Terra’s Humex™ 2 humidity controller is suitable for a wide range of above-ambient target humidity levels and is cross-compatible with many other Terra systems. When paired with Terra’s Dual Purge and NitroWatch systems, chamber RH is adjustable for higher or lower RH levels in the glovebox.

The Humex 2 uses an inline humidity sensor installed inside the enclosure to monitor the relative humidity (RH) level. As soon as the %RH falls below a user-selected threshold, a relay inside the Humex activates the heater and a solenoid valve for water vapor. The low-volume steam output helps to minimize water condensation. Once the %RH set-point is attained, the Humex turns off the heater and water flow.

A2 - Low Humidity/Oxygen (5% RH)

Applications requiring low humidity down to 5% RH can be configured with manual flow-meters or Terra’s automatic gas-purge control systems. Terra offers control systems for different applications and budgets.

Dual Purge™ & NitroWatch™: Terra Universal's Dual Purge™ and NitroWatch™ work together to fully automate moisture control inside a glove box or similar enclosure. This automatic Nitrogen purge control maintains use-specified sub-ambient RH set-point down to 0% ±1.5% RH. The variable-purge system uses high/low flow settings to conserve nitrogen. Programmable logic gives users complete control over warning alarms and other system functions for worry-free operation. The system can be upgraded to include built-in data logging.

Smart® glovebox system: The Smart® control system offers a simplified, lower-cost alternative to the Dual Purge and NitroWatch, ideal for enclosures less than 6 cubic feet. The system features a mini automatic control module mounted to the side of the glovebox. It includes a built-in RH Sensor and LED display to provide automatic RH setpoint control down to 0% RH with binary (on/off) gas flow. Low moisture conditions are maintained by automatically controlling the flow of dry purge gas, generally nitrogen, into the glove box. The automatic RH set point control minimizes necessary supervision and increases the efficiency of N2 gas consumption, cutting nitrogen costs up to 78% when compared to a manual flow meter gas delivery system. The system can encounter limitations and inefficiencies with gas distribution and RH uniformity in chambers larger than 6 cubic feet.

Flow Meter: A manually controlled flow meter offers the lowest up-front cost for RH control. It is most suitable for smaller gloveboxes that do not require much nitrogen gas or those that require minimal supervision. Manual control means humidity control is more prone to human error and not as efficient with the consumption of inert gas, which can lead to high operating costs and damaged materials.

A3 - Ultra Low Moisture/Oxygen (<1% RH)

Critical applications may require moisture concentration levels below 1% RH, which can be measured in parts per million (PPM). Plastic gloveboxes are generally not suitable due to hygroscopic and permeable material properties, which allow moisture and oxygen to leak into the enclosure. Stainless steel gloveboxes offer the best moisture impermeability, making them ideal for ultra low moisture/oxygen applications such as organometallic chemistry, hydrophilic chemical handling, lithium battery production, microelectronics manufacturing, and hemoglobin research.

Gas purging for ultra low moisture/oxygen systems also requires a high volume of nitrogen (or other inert process gas). Gloveboxes and airlocks configured for negative pressure can use vacuum cycling to reduce nitrogen consumption and more rapidly remove moisture and oxygen-rich air.

Even with a plentiful supply of inert gas and a vacuum pump system, reaching ultra low levels with a manual purge control process can be extremely time consuming and require constant supervision. Terra offers a number of automatic purge systems and accessories to improve the efficiency and effectiveness of ultra low moisture/oxygen gloveboxes:

The extreme sensitivity and precision of the DewWatch™ moisture control unit makes it suitable for the most demanding applications. It operates over the -80 to +20 degree C dew point range, which is equivalent to 0.5 PPMV to 23,000 PPMV in gases at 1 atmosphere. It interfaces with Terra's Dual Purge™ variable gas-flow system for completely automatic nitrogen purging.

Trace Oxygen Analyzers are perfect for high-precision oxygen detection inside a glovebox or similar enclosure. They are ideal for applications in which even minute concentrations of oxygen can degrade parts. Zirconium-oxide or electrochemical fuel cell sensor provides long service life, ppm-precision, and rapid response time for increased productivity.

The AtmosPure Re-Gen Gas Purifier produces an ultrapure inert atmosphere for materials sensitive to moisture and/or oxygen by circulating an inert gas and removing oxygen and moisture inside the box. The Purifier has the capacity to remove up to five liters of oxygen (13,500 ppm) and 660 grams of moisture (18 million ppm) at standard temperature and pressure (STP). Depending on the application, glove box liner material and frequency of use, regeneration may be necessary only once every one to three months and completed in only 13 hours.

B - Stainless Steel Design Configurations
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Stainless steel glove boxes are well suited for broad chemical compatibility, sterile-friendly cleaning, and impermeability to moisture/oxygen.

B1 - CleanSeam™ Design

Continuous Seam Welds: Glove boxes with CleanSeam™ design feature a fully welded single piece enclosure with seamless interiors to eliminate hard-to-clean cracks and crevices that can harbor contaminants. The continuous-seam welds are ground smooth to simplify cleaning and sterilization.

B2 - BioSafe® Design

Meets Aseptic Requirements: BioSafe glove boxes are ideal for life science applications and exceed cGMP, IEST, ASTM and ISO 14644-1 requirements. Continuous-seam welds eliminate hard to clean cracks and crevices that can harbor particles and microbes. Round, wide radius corners simplify complete sterilization.

BioSafe® Door with Knife-Edge Seal: BioSafe® Doors are removable for autoclaving and sterilization. A one-piece, heat-formed, non-adhesive gaskets won’t creep or outgas.

A – Air Flow Direction
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There are compelling reasons to choose either airflow system depending on clearance requirements, process location, work surface design, and operator safety. Below is a brief comparison (read more on horizontal vs vertical laminar flow hoods).

A1 – Vertical Laminar Flow: Vertical laminar flow hoods are often selected because they resemble, on a smaller scale, the design of a laminar flow cleanroom, in which fan/filter units (FFUs) are typically positioned in the ceiling

Advantages

• Design fits within a smaller footprint, encompassing less work space.
• Isolated work surface and anti-vibration tables are available for vibration-sensitive work.
• Easier to configure for tall equipment or processes requiring more vertical space.
• The filter, installed above the work surface, is more accessible for maintenance and testing.

A2 – Horizontal Laminar Flow: A horizontal-flow hood requires additional depth to accommodate the rear-mount FFUs with some additional rear clearance to allow air to enter the system. These clearance requirements necessitate a deeper bench and more floor space than a vertical flow system.

Advantages

• Laminar airflow is parallel to work surface, reducing turbulent effects that can occur from vertical airflow striking perpendicular to work surface.
• Easier to position and stagger sterile equipment and materials on work surface closer to the filter face (upstream from other potential contaminants).
• Hands and gloves can rest downstream of samples, less likely to contaminate operations.

B – Format
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B1 – Free-Standing: Free-standing or floor mounted laminar flow hoods are larger in size, mimicking a mini-cleanroom setup. They are more suitable for large equipment or processes that require more open space. Free-standing laminar flow hoods are also generally more suitable for vibration sensitive applications, since they can be configured with a separate work table inside the hood.

B2 – Benchtop: Benchtop laminar flow hoods are generally smaller in size and therefore can offer greater portability to move and mount onto different work surfaces. They may, however, pose a problem for vibration sensitive applications such as microscopy. Certain benchtop laminar flow hoods are available with vibration isolation stands to alleviate this problem.

C – Front Shield
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C1 – Motorized Sliding Shield: Motorized access shields are designed for large, free-standing vertical laminar flow hoods to help improve laminar flow. The position can be lowered to allow partial access to perform work while simultaneously maintaining a protected laminar flow environment. The automatic sliding shield is rated for millions of operations and is connected to a touch-screen PLC controller for easy operation.

C2 – Tilt-Up Shield: Manual tilt-up shields offer a low-cost access and protection solution for laminar flow hoods. The shield helps preserve laminar airflow while simultaneously providing sufficient access to work inside the hood. A hinged shield also allows for easy equipment access and maintenance. They are included with most benchtop hoods and some free-standing hood designs.

C3 – No Shield: Depending on airflow direction, a shield can sometimes inhibit laminar airflow or access to equipment. Some applications using horizontal laminar flow hoods forgo a shield to improve laminar airflow that runs parallel to the work surface.

C4 – Strip Curtains: Strip curtains are designed for large free-standing laminar flow clean booths or mini-cleanrooms. They can drape from ceiling to floor, making them suitable as barriers or entryways for personnel or large equipment. They are also easy to replace and available in several material types, such as ESD safe, non-outgassing, and opaque formulations.

D – Filter Alarm
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D1 – Automatic Alarm System: Filter replacement alarm systems provide automatic replacement alerts to avoid costly and unexpected operational interruptions. They can also improve safety by preventing electrical/fire hazards caused by overworked motors pushing against overloaded HEPA filters. Free-standing vertical laminar flow stations include a programmable filter back-pressure alarm that is integrated into a touch-screen PLC panel. Other laminar flow hoods can be configured with Terra’s add-on filter replacement alarm system. The add-on system also allows control of the differential pressure set-point to adjust frequency of filter replacement. It includes a visual differential pressure gauge, visual flashing indicator light, and an audible buzzer with silencer that sounds when set point level is exceeded.

D2 – Visual Differential Pressure Gauge: Stand-alone visual differential pressure gauges can be configured to most laminar flow hoods to help monitor and control airflow in a laminar flow hood. This simple monitoring device with a low up-front cost helps confirm the hood is operating and supplying proper airflow. However airflow control and filter replacement monitoring can be more susceptible to human error since the stand-alone pressure gauge does not include an automatic alarm system.

E – Work Surface
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E1 – Vibration Isolated: Laminar flow hoods compatible with vibration isolated work surfaces can be configured to fit a separate work table inside the hood. They are recommended for vibration sensitive applications such as microscopy.

E2 – Integrated: Laminar flow hoods with built-in cleanroom-compliant work surfaces can enhance cleanliness and safety. Because the attached workstation transmits fan vibration, this design is not recommended for delicate operations with microscopes, scales, balances, or other precision instruments.

F – Frame Material
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F1 – 304 Stainless Steel: 304-grade stainless steel resists most harsh chemicals and alcohol-based cleaning agents, and won’t produce contaminants during sterilization.

F2 – Powder Coated Steel: Powder-coated steel offers a lower cost alternative to stainless steel that is still more durable and rigid than plastic designs. Powder-coated steel has slightly lower chemical and moisture resistance compared to stainless steel.

F3 – Polypropylene Plastic: Opaque polypropylene is most suitable for wet chemistry applications. It offers excellent chemical resistance against common acids, solvents, and disinfectants. The solid polypropylene frame features continuous-seam welds for easy cleaning and maximum protection against chemical splashes and spills.

G – Side Panels
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G1 – Interchangeable Plastic Side Panels: Removable side-panels increase the versatility of your hood by improving visibility and/or simplifying equipment access and maintenance. The side-panels are lined with foam gasket and slide into the hood’s frame for a simple yet effective sealed fit, free of troublesome fasteners or screws. Side panels can also be configured with application specific materials to help support required conditions inside the hood, such as:

• Visibility
• Light sensitivity
• Electrostatic discharge (ESD) safety
• Chemical resistance
• Thermal extremes

Below is a list of standard side-panel materials:

• Clear Acrylic
• Static-Dissipative PVC (SDPVC)
• Polycarbonate
• Black Acrylic
• Amber Acrylic
• FM4910 Polypropylene
• FM4910 CPVC
• White Acrylic

G2 – Solid Steel: Laminar flow hoods with solid steel walls are most suitable for critical cleanliness applications that require frequent disinfection. The design simplifies cleaning by minimizing cracks and crevices where particles or germs can collect.

G3 – Solid Polypropylene Plastic: Polypropylene hoods are most suitable for wet chemistry applications. The solid polypropylene frame and walls feature continuous-seam welds for easy cleaning and maximum protection against chemical splashes and spills.

G4 – Strip Curtains: Strip curtains are designed for large free-standing laminar flow clean booths or mini-cleanrooms. They can drape from ceiling to floor, making them suitable as barriers or entryways for personnel or large equipment. They are also easy to replace and available in several material types, such as ESD safe, non-outgassing, and opaque formulations.

H – Upgraded Features
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H1 – Energy-Efficient EC FFUs: Energy efficient FFUs offer lower operating costs, longer service life, and precision control of fan speed.

H2 – Room-Side Filter Replacement: Room-side replaceable (RSR) filters drastically simplify filter replacement. These filters can be easily removed and replaced without disassembling the bulky FFU from the hood. RSR filters feature a gel-seal to form a tight seal against the "knife-edge" on the blower housing.

H3 – Explosion-Proof Design: An explosion-proof laminar flow hood is designed to work in hazardous areas with risk of ignition due to flammable fumes or explosive dusts. All electrical components in explosion-proof hood designs are rated compliant for hazardous locations Class I, Division 1, Groups C & D and Class II, Division 1, Groups F ∓ G. This includes the fan filter unit (FFU), LED lights, wiring, and on/off switches.

H4 – ULPA filter: HEPA filters are rated 99.99% efficient at filtering particles down to 0.3 microns. ULPA filters are rated 99.999% efficient at filtering particles down to 0.12 microns. ULPA filters are suitable for achieving sub-class 100 particle counts. However due to the denser filter media, ULPA filters have more restricted airflow which can negatively affect flow rate and air changes per hour (ACH) within the work area.

H5 – Germicidal UV Lamp: UV lights can be built into laminar flow hoods to help decontaminate the hood after use. The UVC disinfection Module includes a timer plus "exposure switch" to protect users from exposure to harmful UV light.

H6 – Static-Neutralizing Ion Bar: Intrinsically safe low-voltage ionizing bars mount to a fan/filter unit inside a laminar flow hood to neutralize static charges that can lead to electro-static discharge and particle attraction. These units emit equal numbers of positive and negative ions and require no calibration or adjustments. The narrow profile minimizes any disruption to laminar flow inside the hood.

H7 – Rear Plenum for Internal Air Recirculation: An adjustable rear plenum on the back wall of the hood recirculates air to minimize turbulence in the work area and extend filter life.

H8 – Peripheral Air Return Ducts: Return air ducts help maintain laminar flow and keep particles out. Horizontal laminar flow stations feature return ducts along the bottom and side edges of the front opening. These ducts reduce backwash caused by placing objects near the work surface edge, a common source of turbulence inside a clean bench. On less sophisticated systems, an object placed near the front edge of a horizontal air-stream interrupts the laminar flow and provides an opportunity for unfiltered air to wash back into the work area, bringing contaminants with it.

H9 – Duplex Power Outlets: GFCI power receptacles installed on the interior of the hood provide operational convenience. Alternative mounting locations can be specified at time of order.

H10 – Utility Valves: Ball valves (petcocks) are available for utilities such as nitrogen, compressed air, vacuum, DI water, or other process gases. Valves are available in chrome-plated steel or ABS plastic.

H11 – Casters: Casters offer greater mobility for free-standing hoods. They allow hassle-free movement to different locations and facilitate cleaning under and around the work area.

A - Fan Filter Air Flow Design
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A1 - Positive Pressure Fan Filter Units

Terra's positive pressure fan filter units include HEPA fan blowers capable of ISO Class 3 - ISO Class 8 air quality conditions. ULPA filtration units are available for the most sensitive ISO 3 - ISO 5 product applications including pharmaceutical compounding, semiconductor wafer processing, sterile packaging, and micro/nanofabrication.

A2 - Negative Pressure Fan Filter Units

Reverse-flow impeller FFUs capture particles generated in localized cleanroom spaces to minimize contamination and ensure operator protection.

Terra's negative pressure fan filters provide capable and safe production environments for reducing operator hazards in increased-risk applications such as USP 800 compounding, infectious disease research, and chemically intensive processes that require volatile chemical handling.

B - Compatible Cleanroom Fan Filters
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B1 - HEPA Fan Filter Units

HEPA filters remove 99.97% of airborne particles greater than or equal to 0.3μm in diameter. HEPA fan filter units are common for contamination and air quality control for industries including pharmaceuticals, medical devices, OEM assembly, healthcare, life sciences, infection control, and laboratory or testing environments.

B2 - ULPA Fan Filter Units

ULPA filters are 99.999% efficient for monodispersed particles 0.12 μm in diameter or larger. ULPA filtration offers additional particulate control for ultra-sensitive hardware including display panels, wafer chips, microoptics, satellite imaging, and nanotechnology applications.

C - Filter Replacement Design
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C1 - Top-Side Fan Filter Units

Top-side replaceable filters are a standard package available with Terra fan filter units. Standard FFUs offer a lower cost option and are ideal for small-scale and less critical cleanroom operations. To change the filter, the unit must be entirely pulled out of the ceiling bay. Climbing up to remove the bulky FFU can be difficult, dirty, and hazardous. The procedure may require tall ladders, multiple people, personal protective equipment, and perhaps worst of all, shutting down the cleanroom.

C2 - Room-Side Fan Filter Units (RSR)

Room Side Replaceable (RSR) fan filters eliminate the need for access to a roof or overhead ceiling space when conducting fan filter maintenance and replacement. Breaching the cleanroom ceiling is not required when installing or replacing RSR fan filter units or their HEPA filter media. The filter media is easily accessible from inside the cleanroom, an ideal trait for facilities with restricted ceiling heights or for pharmaceutical operations that require more frequent HEPA filter replacements.

D - Fan Filter Motor Type
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D1 - Electronically Commutated (EC)

Terra's Smart® electronically commutated (EC) brushless motors include an internal microprocessor and MODBUS® networking control card. Easily integrate your fan filter with a building management system, control panel, or additional air pressure, airflow, and particle count sensors.

D2 - Permanent Split Capacitor (PSC)

PSC motors are priced for affordability but are significantly less energy-efficient than their EC counterparts.

Read more: FFU Costs for an Energy-Efficient Cleanroom

D3 - None (HVAC Connection)

Motorless fan filter units include ducted collars for connection to an existing air handling unit or pre-conditioned air supply. Unlike actively powered FFU motors, motorless designs do not require electrical connections. The lightweight assembly makes for easy ceiling grid installation and includes the same baffles, diffusers, and HEPA media for smooth, quiet, and uniform air delivery.

E - Construction Material
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E1 - Stainless Steel Fan Filter Units

Stainless steel is a gold standard among cleanroom construction materials. Easy cleaning, favorable heat properties, and chemical resistance make stainless steel an ideal choice for biopharmaceutical and semiconductor environments. The smooth surface is easy to wipe down, resists biofilm buildup, and will not off-gas.

E2 - Powder-Coated Steel Fan Filter Units

Powder-coated steel is an economical choice that also provides favorable heat and chemical resistance for most applications. Terra’s signature white powder coat finish provides a high quality, durable barrier to protect against corrosion, plus a clean and attractive aesthetic. The advanced heat-fuse formulation exceeds ASTM and ISO paint standards to resist chipping, scratching, fading, and wearing.

F - Fan Filter Size
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Terra provides several fan filter unit sizes and styles to accommodate your existing ceiling grid. Each configuration is available with optional duct collars and optional 1/4 inch (6 mm) eyebolts in all (4) corners for hangwire support (order eye bolt package separately).

F1 - 24" x 24" Fan Filter Units

2' x 2' fan filters provide moderate flow rates and accommodate standard square ceiling grid installations. Lightweight (25 lbs) provides easier installation.

Approximate Weight: 25 LBS

F2 - 24" x 36" Fan Filter Units

2' x 3' fan filter units are intended for use with supported ceilings that can safely bear the weight of a fan filter unit or light panels to be installed. HEPA/ULPA packages provide a uniform flow of microfiltered air to meet cleanliness standards down to Class 10 (ISO 4).

Approximate Weight: 53 LBS

F3 - 24" x 48" Fan Filter Units

2' X 4' fan filter units accommodate standard cleanroom ceiling grid and laminar flow hood configurations and are intended for use with supported ceilings that can safely bear the weight of a fan filter unit or light panels to be installed. HEPA/ULPA filters provide a uniform flow of microfiltered air to meet cleanliness standards down to Class 10 (ISO 4). Optional with 1/4 inch (6 mm) eyebolts in all (4) corners for hangwire support (order eye bolt package separately).

Approximate Weight: 71 LBS.

F4 - 16" x 24" Fan Filter Units

Narrow fan filter units fit in a space-saving enclosure for a smaller footprint. Optional with 1/4 inch (6 mm) eyebolts in all (4) corners for hangwire support (order eye bolt package separately)

F5 - 16" x 36" Fan Filter Units

Narrow fan filter units provide a space-saving enclosure for a smaller footprint. Optional with 1/4 inch (6 mm) eyebolts in all (4) corners for hangwire support (order eye bolt package separately)

Approximate Weight: 50 Lbs

F6 - 16" x 48" Fan Filter Units

Narrow fan filter units fit in a space-saving enclosure for a smaller footprint. Optional with 1/4 inch (6 mm) eyebolts in all (4) corners for hangwire support (order eye bolt package separately)

Approximate Weight: 50 Lbs

G - Fan Filter Voltage
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G1 - 120 Volt Fan Filter Units

Standard 120 volt connection is suitable for standard residential power outlets in the US. Ideal for powering mobile-mounted fan filter units. Black and red wires are connected to the lower terminal. A along with a yellow jumper cable.

G2 - 240 Volt Fan Filter Units

240V connections require less current (amperage) and smaller conductors than appliances designed to operate at 120V. Ideal for fan filter units with optional heating, cooling, ionization, or UV lighting modules.

H - Special Fan Filter Application Features
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H1 - Integrated LED Fan Filter Light

Fan filter units with integrated LED lights enable 100% coverage of a ceiling grid with fan units while also providing adequate lighting. 100% integration of the ceiling grid is typically reserved for high-performance environments with ISO Class 5 ratings or cleaner.

H2 - Integrated Fan Filter Ionizer

Integrated ionizers provide a continuous stream of static-neutralizing ions to protect sensitive materials against ESD. Built-in ionizers enhance cleanliness by neutralizing charges that attract and hold particles on walls, tabletops, and other surfaces. Ionizers are known for being maintenance burdens that require frequent calibration. Unlike ionization technologies offered by Terra competitors, Terra systems require no calibration and automatically maintain a balance of ± 50 volts.

H3 - Automated Fan Filter Control & Pressure Balancing

Terra's Smart® Fan Filter Units paired with Smart® Cleanroom Control Panels adjust the fan speed up or down to “dial in” the proper air velocity, internal pressure, and air change rate. Variable fan filter control lets you balance FFU performance from one clean zone to another, ensuring that you maintain the pressure gradients and air change rates required. As the filters mature and air velocity decreases, the system lets you perform small speed adjustments that keep your cleanroom performing to spec.

H4 - Portable Fan Filter Units

ValuLine portable fan filter units are mobile, self-contained, hospital-grade HEPA purifiers mounted on a rolling stand. The small footprint, rolling stand, and plug-and-play operation allow easy transfer between rooms or departments.

H5 - NEC Class 1/Division 1 Compliant

Terra's explosion-proof fan filter units isolate fumes and vapor from any spark, hot surface, or friction-inducing electrical components.

Explosion-proof LED lights are available with a T5 temperature rating and are designed for low-profile pendant mounting to make maximum use of available space.

Division I environments contain ignitable concentrations of hazards under normal operating conditions and/or where the hazard is caused by frequent maintenance or repair work or frequent equipment failure.

Class I locations are those in which flammable vapor and gases may be present.

H6 - Remote Air Supply Connection

Terra's Laminar Flow Diffusers with HEPA Filters include a 12"-diameter collar for air supply connection for connecting the fan filter assembly to a remote air source. Threaded inserts in the top corners accommodate eyebolts to facilitate installation using suspended guy wires (order eyebolt packages separately).

H7 - 8" Tall Unit for Restricted Height Spaces

Low-profile 8"H fan filter units are ideal for cleanrooms installed within restricted height areas.

H8 - Integrated UPS Battery System

An Uninterruptible Power Supply (UPS) is a backup system that provides battery power to fan filter units when utility power is unavailable. In the event of a power outage, the UPS immediately activates without interruption and recharges when power is restored.

Smart® EC Fan Filter Units with UPS keep your FFU running long enough to safely store away contamination-sensitive materials, shut down work-in-progress, and/or switch to a backup power generator. Handy and convenient, the Uninterruptible Power Supply (UPS) provides power when and where you need it. The included external 24V battery pack offers extended battery runtime when used with the main tower UPS system.

H9 - Cleanroom Fan Filter Contaminant Collector Pan

A fan filter collector pan accumulates dust particles that dislodge from the HEPA filter, preventing contaminants from re-entering the cleanroom. Terra's collector pan integrates with bag-in/bag-out (BIBO) systems and is easily removed for cleaning or maintenance.

Bag-in/Bag-out (BIBO) modules are optional accessories for applications involving toxic fumes or biohazards. BIBO modules seamlessly integrate with the filter media system for safe filter disposal and replacement from the inside of the room for contact-free removal of filters with potentially hazardous airborne contaminants.

H10 - Fan Filter Heating Element (up to 150°F)

Heated fan filter units provide high-temperature air of up to 150 degrees Fahrenheit.

H11 - Fan Filter VOC Removal Adapter

Volatile Organic Compound (VOC) Removal Adapters require an adapter module for each FFU. The package includes an adapter housing, one charcoal pre-filter, two sanitizing modules, and one PCO panel and must be ordered together with a Terra WhisperFlow FFU.

Photo-Catalytic Oxidation Panels (PCO) remove volatile organic compounds (VOCs) remaining in the air stream after they pass the carbon filter. The PCO panel is highly efficient at vapor removal, yet imposes no restrictions on airspeed, allowing the Fan/Filter Module to maintain airspeed consistent with ISO cleanliness requirements (typically 80-100 feet/minute).

The carbon pre-filter removes volatile organic compounds (VOCs) to ensure a safe, clean processing environment. The pre-filter also helps compensate for VOC spikes that might occur during certain operations.

H12 - Fan Filter UV Sterilization Module

Terra Fan Filters Units with integrated UVC decontamination modules provide additional protection against bioaerosols and pathogenic organisms. UV-C lamps may not produce an entirely sterile surface, but they can maintain consistently low microbial loads throughout a wide range of operations and eliminate bioburden spikes that could necessitate extensive testing and decontamination measures. UV Sterilization modules are not compatible with the following FFU designs: Narrow, Explosion Proof, or Reverse Flow.

H13 - Cleanroom Leak Testing Challenge Port

Fan filter units with challenge ports provide a simple and efficient mechanism for conducting localized leak tests of each filter. Terra fan filter units are leak tested before delivery in accordance with IEST and UL 900 standards. For critical applications, the USP <797> framework requires that fan filter units undergo leak testing during initial installation, and semiannually throughout the life of the filter. Filter testing is also common in operating rooms, surgical suites, and CGMP facilities.

Leak testing requires the injection of an aerosol upstream of the filter. Fan filters with challenge ports allow for rapid and individual testing of each fan filter unit without requiring the introduction of test aerosols to the entire HVAC system. Challenge port testing is a more reliable method of ensuring that a test aerosol is uniformly applied and presents fewer variables.

I - Compatible Control Systems
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I1 - Cleanroom Fan Filter Power Distribution Module

Terra’s Power Distribution Modules (PDMs) use 3-pin or 4-pin quick connect fittings to power all FFUs and lights, regardless of the cleanroom size. The expertise of a licensed electrician is only needed to connect the main voltage to the Primary, Secondary, and Booster PDM modules; lights and fan filters are installed via quick-connect fittings without requiring hard wiring. The PDM modules must be wired to a dedicated 35A fused 120V circuit or a 30A fused 240V circuit to allow a quick fit connection of up to 5 light and 5 FFU connections per module.

I2 - Cleanroom Fan Filter Replacement Alarm System

Fan Filter Replacement Alarms provide a reliable, quantitative method for determining when HEPA fan filter media requires replacement. Automatic replacement alerts avoid costly and unexpected operational interruptions while also maximizing the working life of the fan filters.

I3 - Smart Control Panel for Filter Fan Units

Standard Control Panels provide central control and connection of lights and filters. An optional Night Service Switch drops all Fan/Filter Units (FFUs) into a low-energy mode for nights and weekends.

Smart® Control Panels connect to EC FFUs for individual or grouped fan control and remote monitoring of room differential pressure, particle counts, temperature, and humidity. The robust system offers advanced control for up to 200 fan filter units and 16 independently controlled rooms.

An upgraded Smart® Control System allows additional environmental sensors and FFU control to meet critical performance/monitoring requirements including programmable fan speed adjustment for energy savings, performance enhancement, or remote shutdown. Easily connect additional sensors to display humidity, differential pressure, and temperature data.

J - Compatible Accessories
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J1 - Cleanroom Fan Filter Unit Mounting Frames

Stainless steel mounting frames allow fan filter units or light panels to be installed in drywall or other hard ceilings without a ceiling grid.

J2 - Cleanroom LED Lights

Cleanroom LED lights are energy-efficient, produce low heat, carry long life spans, and are compatible with ISO class 3 spaces.

J3 - Cleanroom UV Lights

Although UV-C lamps may not produce an entirely sterile surface, they can maintain consistently low microbial loads throughout a wide range of operations and eliminate bioburden spikes that could necessitate extensive testing and decontamination measures.

J4 - Cleanroom Emergency Lights

Cleanroom LED Light Panels with Built-In Emergency Batteries allow for temporary backup lighting during a power outage. When receiving power, the light operates normally and charges the emergency battery. A UL recognized emergency driver allows the LED fixture to be used for normal and emergency operation. The LED light has a red/green indicator to inform employees after power has returned and the cleanroom is safe to re-enter.

J5 - Cleanroom Ceiling Panels

Cleanroom ceiling panels cover ceiling bays not occupied by fans or lights. These panels are available in several materials that support frequent cleaning and will not absorb water or crumble like conventional gypsum ceiling panels. Chemically resistant polypropylene panels are preferable for use with most chemical solvents and acids. Stainless steel panels are typical for pharmaceutical and USP-regulated environments that require aggressive chemical sterilants or vapor treatments during cleaning regimens. Vinyl-covered gypsum is cost-effective and fire-rated but does not offer the wider chemical compatibility of other materials. All Terra ceiling panels are cleanroom appropriate for ISO Classes 5 to 8 and Federal Standard 209 Classes 100 to 100,000.

Terra Universal is the leading US manufacturer of critical environment equipment with a diversified product line including cleanrooms, desiccators, hoods, glove boxes, cleanroom furnishings and similar equipment.

Shop online to view a wide selection of fan filtration systems, cleanroom components, and controlled environment enclosures.

Contact a Terra cleanroom specialist for assistance with product configuration or application compliance via web chat, email, or phone.

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