Resources
Filtration and bioprocessing glossary
The terms that appear in catalogs, specifications and validations, explained in a few lines.
2
- 222 and 226 adapters
- Ends of 2.75″ cartridges that fit into the housing with two O-rings: 222 and 226 are the standard sizes of those O-rings. The opposite end can be closed with a fin (arrowhead) or flat. Each cartridge's code indicates the configuration.
- 2D bag and 3D bag
- 2D single-use bags are flat, made of two welded sheets, and are used for small and medium volumes. 3D bags are three-dimensional and, for large capacities, are held in a rigid container that supports them. Single-use
A
- Absolute and nominal rating
- An absolute rating means that the medium retains, with a defined and tested efficiency, all particles equal to or larger than the stated rating. A nominal rating is a size reference without that commitment: some of the particles of that size may pass through. Prefiltration
- Acholeplasma laidlawii
- A mycoplasma used as the challenge organism for 0.1 µm membranes. Because mycoplasmas have no cell wall and are very small, retaining them requires a tighter pore than 0.2 µm.
- AISI 316L and AISI 304
- Austenitic stainless steels. 316L adds molybdenum, which improves resistance to pitting corrosion in the presence of chlorides, and has low carbon (the “L”), which reduces sensitization during welding. 304 is the usual choice in food and beverage. 304 or 316L
- ASME BPE
- The American Society of Mechanical Engineers (ASME) standard for bioprocessing equipment: materials, surface finish, drainability, hygienic design and documentation of product-contact parts. It is not a pressure code: if the equipment works under pressure, that is addressed separately. Tanks and reactors
- ASTM F838
- Standard that describes how to determine the bacterial retention of membrane filters used for liquid filtration. The membrane is challenged with Brevundimonas diminuta at 10⁷ CFU per cm² of filtration area; a sterilizing-grade filter must produce a sterile effluent. Sterilizing filtration
- Asymmetric membrane
- A membrane with more open pores on the inlet face that narrow toward the final pore size. It retains in depth within its thickness and usually provides more flow and dirt-holding capacity than a symmetric membrane of the same rating.
- Autoclave
- Equipment that sterilizes with saturated steam under pressure, typically at 121 °C. Many cartridges and housings accept autoclave cycles; the number and duration of the cycles depend on the model.
B
- Baffle box
- Pretreatment at the inlet of a coalescer vessel: several baffles that make the gas change direction, so contaminants and the largest droplets separate before they reach the filter element. Gas coalescer vessel
- Beta ratio (β)
- Ratio of the number of particles of a given size upstream of the filter to the number downstream. A β of 1,000 is equivalent to an efficiency of 99.9% for that size.
- Bioburden
- Number of microorganisms present in a fluid or on a surface before a reduction or sterilization step. Reducing it with prefiltration protects the final filter.
- Bioreactor
- A reactor in which cells or microorganisms are grown under controlled agitation, temperature, pH and dissolved oxygen. In stainless steel, it is cleaned by CIP and steam-sterilized (SIP) between batches. RLQ reactor
- Brevundimonas diminuta
- Small bacterium (ATCC 19146) used as the challenge organism to qualify 0.2 and 0.22 µm sterilizing-grade filters per ASTM F838.
- Bubble point
- Minimum gas pressure that displaces the liquid from the largest pores of a wetted membrane and produces a continuous gas flow. It is related to pore size: a value below the specified one indicates an integrity failure. Integrity test
C
- Change-out differential pressure (ΔP)
- Pressure difference between the filter inlet and outlet at which replacement is recommended. It increases as the medium clogs.
- CIP and SIP
- CIP (clean-in-place) is cleaning equipment without disassembling it, with solutions that circulate through the system. SIP (steam-in-place) is sterilization with steam in place.
- Coalescence
- Process by which fine droplets of a liquid dispersed in a gas merge into larger drops, which run down under their own weight and are drained. It is the principle behind coalescer cartridges. AeroSep coalescers
D
- Demister
- Mist eliminator: a pack of wire mesh that forms a dense body. Droplets carried by the gas hit the wires, agglomerate by molecular attraction and, once they grow, fall by gravity to the bottom of the vessel. Gas coalescer vessel
- Diffusive flow (forward flow)
- Non-destructive integrity test: with the membrane wetted and at a pressure below the bubble point, the gas that diffuses through the liquid in the pores is measured. A value above the limit indicates a failure. Integrity test
- DOE and SOE
- DOE (double open end): a cartridge open at both ends that seals with flat gaskets compressed by the housing. SOE (single open end): open at one end only, with O-rings, and with the other end closed.
E
- Extractables and leachables
- Compounds that can migrate from the materials of the filter or system into the fluid. Extractables are obtained under exaggerated laboratory conditions; leachables, under actual conditions of use. USP <665> covers plastic components used in pharmaceutical manufacturing.
F
- Filter separator
- Two-stage equipment for gas: the first stage retains solids and enlarges the droplets (pre-coalescence); the second, a coalescer or vane pack, separates the liquid, which is drained. How it works
- Filtration skid
- Assembly of housings, valves, instruments, and piping mounted on a frame, ready to connect to the process.
G
- Glass microfiber
- Filter medium made of very fine glass fibers with a high holding capacity for particles and colloids. It is used as a prefilter and for clarification. MicroFiber
H
- Heating jacket
- An enclosure welded onto the shell of a tank through which steam, hot water, thermal oil or glycol flows to heat or cool the product without touching it. A half-pipe jacket is a pipe cut in half lengthwise that wraps around the shell and continues in coils across the bottom. Tanks and reactors
- High Flow cartridge
- Large-diameter (6″), high-flow cartridge, 20 to 60″ long, with inside-to-outside flow. It can filter large flow rates with few units in horizontal or vertical housings. SaniFlow HF
- Hydrophilic and hydrophobic membranes
- A hydrophilic membrane is wetted by water and filters aqueous solutions without prior treatment. A hydrophobic membrane repels water: it lets gases through and is used in vents and air filtration.
I
- Integrity test
- A test that verifies that a filter has no defects and performs like the validated filter. The most widely used are bubble point, diffusive flow, and pressure hold.
- ISO 7 cleanroom
- An environment with airborne particle concentration controlled per ISO 14644-1, Class 7. At Exova, filter cartridges, bags, and single-use systems are manufactured in an ISO 7 cleanroom. Manufacturing
L
- Load cell
- A sensor that measures the weight of the tank and its contents. With load cells, product is formulated and transferred by weight (gravimetric formulation) instead of by level. Tanks and reactors
M
- Magnetic agitation
- Agitation in which the motor stays outside the tank and drives the impeller inside through a magnetic coupling in the bottom. Since no shaft goes through the wall, there is no seal that can leak and no area the CIP cannot reach: that is why it is used in sterile processes. MAG reactor
N
- Nylon 6,6
- Polyamide used to make naturally hydrophilic membranes, which wet with water without additives. UltraPure
P
- Passivation
- Chemical treatment of stainless steel that removes free iron from the surface and promotes the chromium oxide layer that protects it from corrosion.
- Pleated polypropylene
- Polypropylene microfiber medium folded into pleats to increase the filtration area. It has broad chemical compatibility and is used in prefiltration and clarification. ProFlow
- Polyethersulfone (PES)
- Polymer used to make high-flow, low-adsorption hydrophilic membranes, widely used in sterilizing and beverage filtration. LifePure
- Prefiltration
- A stage that retains particles, colloids, and part of the bioburden ahead of the final filter, to extend its service life and lower the cost per filtered liter. Prefilter cartridges
- Pressure hold test
- Integrity test in which the inlet side is pressurized and the pressure drop over a given time is measured. It is an indirect way of measuring diffusive flow.
R
- Ra surface roughness
- Arithmetic mean of the deviations of a surface profile, in µm. In sanitary equipment, a low Ra (for example ≤ 0.4 µm in contact with the product) makes cleaning easier and reduces residue adhesion. SaniFlow housings
S
- Sanitary clamp connection
- Sanitary joint made of two ferrules with a gasket between them and a clamp that tightens them together. It can be disassembled without tools and leaves no threads exposed to the product.
- Single-use system
- Disposable bags, tubing, connectors, and filters that arrive ready to use and are replaced after each batch. They eliminate cleaning and its validation, and reduce the risk of cross-contamination. ExoFlex
- Sterilizing-grade filter
- A filter that, when challenged with Brevundimonas diminuta at 10⁷ CFU per cm², produces a sterile effluent. In practice, this means 0.2 or 0.22 µm membranes (and 0.1 µm when mycoplasmas are also targeted) qualified for that use. Membrane cartridges
U
- USP <88> Class VI
- In vivo biological reactivity tests for plastics in the United States Pharmacopeia. Class VI is the most stringent in the classification and is required for materials in contact with pharmaceutical products.
W
- Wetting
- Filling the pores of a membrane with a liquid that wets it according to its nature (water for hydrophilic membranes). It is a prerequisite for bubble point and diffusive flow tests.
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