A tank that breathes unfiltered air contaminates what it stores.
Every fill and every draw-down moves air through the vent. A vent filter has to stop particles and micro-organisms in both directions and still let the tank hold ambient pressure. Size it for the particle load alone and it can starve the tank of air after steaming, push past the tank's vacuum rating, or fill with condensate, and the process stops.
Where does your process breathe?
Storage and hold tanks
Tanks that draw air in as they empty and push it out as they fill, including purified water hold tanks.
Product transfer vessels
Liquid transfer in API, pharmaceutical, food and beverage plants, where the vessel must hold ambient pressure while product moves.
Fermenters and bioreactors
Sterile barriers on the inlet and exhaust air of fermenters and bioreactors.
Nitrogen blanketing
Clean, dry, sterile gas over product in food and pharmaceutical storage.
Machine and compressed air
Pneumatic and compressed air systems that need air free of particles of a specified size.
Autoclaves and sterile venting
Autoclave vents and sterile gas lines that keep external contamination out of the product.
How is a vent filter sized?
| Design factor | What it decides |
|---|---|
| Particulate load and process flow | Filtration area and retention rating |
| Air flow after steaming | Capacity to replace steam with air as the tank cools, without drawing a vacuum |
| Vacuum rating of the tank | Minimum flow the vent must pass during draw-down |
| Operating environment | High moisture or dry service, and so the need for condensate control |
| Location of the tank and filter | Access, drainage and heat tracing |
| Safety margin | Oversize allowance, plus a coarse prefilter or safety device against in-process downtime |
| Integrity testing | In-situ or off-line test capability with correlated removal efficiency |
| Condensate control | Heat-traced or steam-jacketed housings, drainable housings, piping laid to drain |
| Cleaning and sterilisation | CIP and SIP capability of the housing and the element |
What the datasheets commit to
Housing finish and envelope
Clary-T Vent housings: internal finish Ra 0.4 micron or better, electropolished and crevice free; minus 25 C to 135 C; minus 1.0 to 7.0 bar.
Design codes
Designed to cGMP and GEP; ASME Section VIII Division 1 with U-stamp or UM-stamp, or CE marking under the Pressure Equipment Directive 97/23/EC, on request and subject to engineering review.
Seals and contact materials
Seal materials stated to comply with USP 88 Class VI biological reactivity tests, documentation on request; silicone and EPDM O-rings.
Sterilisation data on the element
Clarypleat PTFE vent cartridges are rated for up to 100 steam-in-place cycles of 60 minutes at 126 C, with bacterial endotoxin of 0.25 EU/mL or less.
Clary-T Vent housing, as specified
| Housing material | SS 316L wetted; SS 304 closure clamp |
|---|---|
| Internal finish | Ra 0.4 micron (15 microinch) or better, electropolished, crevice free |
| Pressure rating | Minus 0.1 to 0.7 MPa (minus 1.0 to 7.0 bar) |
| Operating temperature | Minus 25 C to 135 C |
| Connections | Tri-clover, DIN flange or ASA 150 flange, 1/4 to 3 inch; tri-clover drain and vent |
| Cartridge fitting and length | Code 7; 5, 10, 20 and 30 inch; junior housing on request |
| O-rings | Silicone, EPDM, others on request |
| Options | Jacketed housings, temperature controllers |
Datasheet values from the Clary-T Vent product page. Confirm against the current catalogue and your design code before specification.
Clarypleat PTFE vent cartridge, as specified
| Media | Hydrophobic PTFE membrane on polypropylene support and cage |
|---|---|
| Retention ratings | 0.05, 0.1, 0.22, 0.45 and 1.0 micron |
| Membrane area | 0.74 m2 or more per 10 inch length |
| Maximum operating temperature | 80 C |
| Steam in place | Up to 100 cycles of 60 min at 126 C, or up to 40 cycles at 140 C, differential pressure 0.3 bar or less |
| Bacterial endotoxin | 0.25 EU/mL or less |
| Extractables | 15 mg per 10 inch or less |
| Lengths | 10, 20, 30 and 40 inch |
Values from the Clarypleat PTFE product page, tested and packed in a clean room. Integrity test values are confirmed per application.
Which properties should a vent filter have?
- Hydrophobic media
- High gas flow at low differential pressure
- Bi-directional flow capability
- Thermal and mechanical resistance for long service
- No fibre release and no particle shedding
- Integrity testable, with correlated removal efficiency where the application needs it
- Rated for repeated steam sterilisation where relevant
- Documentation that meets your industry's regulatory requirements
Industries that specify vent filtration
Vent filtration: direct answers
What does a vent filter do that an air filter does not?
A vent filter works in both directions. It is a sterile barrier that removes micro-organisms and viruses from air or gas flowing either way, and it lets the tank hold ambient pressure while liquid is transferred in or out. An air filter on a compressed air line cleans air flowing one way.
Why does the vent filter need to be hydrophobic?
Vent filters are built from hydrophobic media, such as PTFE membrane, so that moisture does not wet the membrane and close the air path. That is also why condensate control on the housing matters as much as the element.
How do you stop condensate forming in the vent housing?
Three ways, often together: steam-jacketed or electrically heat-traced housings that keep the housing above the dew point, drainable housing designs that let condensate out, and piping laid so condensate does not collect at the filter.
Can the whole assembly be steam sterilised in place?
Yes. Clary-T Vent housings are steam sterilisable and designed for CIP and SIP, and Clarypleat PTFE vent cartridges are rated for up to 100 steam-in-place cycles of 60 minutes at 126 C. Integrity testing in situ or off-line is specified with the application.
Send us the tank, not just the flow.
Tank volume and vacuum rating, fill and draw rates, steaming cycle, location and required integrity test. We will size the vent filter and housing and state the margins we used.