Sintered Filter Technical Specifications
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The dull side faces the flow. Every disc, every application, no exceptions.
Temperature and pressure, do not exceed
| Disc | Max temperature | Max pressure | Max differential | Clogged when |
|---|---|---|---|---|
| 4" tri-clamp | 250°F (121°C) | 600 psi | 80 psid | It will not flow solvent at 15 psig |
| 6" tri-clamp | 250°F (121°C) | 250 psi | 60 psid | It will not flow solvent at 15 psig |
The pressure rating applies to the clamp assembly. The differential rating is the most pressure difference allowed across the disc itself.
Orientation: dull side toward the flow
A sintered disc is not the same on both sides. The shiny face is built from coarser wire and has the larger pores. The dull face is built from much finer wire and has the smaller pores. Cut a disc in cross section and the pore structure is funnel shaped: the shiny face is the wide mouth of the funnel, the dull face is the narrow throat.
Flow into the shiny side and solids follow the taper inward. Oleoresin, wax and CRC media are carried down the funnel and wedge into the narrowing channel. They are now inside the media, not on it. You cannot brush that out, the filter never comes fully clean, and it clogs sooner on every run after that.
Flow into the dull side and nothing gets in. The smallest openings are the first thing the material meets, so the solids stop at the surface as a cake. Brush it off, ultrasonic it, blow it back out the same fine face that caught it, and the filter is clean.
In a top-down column: dull side UP, shiny side DOWN. There is no case where the shiny side goes first.
- Filtering oleoresin: dull side up, facing the incoming flow.
- Adsorptive scrubbing media such as T-41 activated bleaching clay or 10 percent activated carbon: dull side up here too. A paper filter above the first disc is optional and helps prevent clogging from trapped media.
- In-line material filtration: pick sizes per need, 25 µm, 10 µm and so on, dull side facing the incoming material.
- Stacking: step down in micron rating in the direction of flow, for example a 5 µm disc followed by a 1 µm disc. Every disc in the stack is oriented individually, dull side toward the flow, not just the top one.
Measured: what the wrong side costs you
The same used discs, flow tested with each face toward the water before cleaning. One U.S. gallon, average of 1 to 9 trials each.
| Micron | Dull side to flow | Shiny side to flow | Shiny side is |
|---|---|---|---|
| 50 µm | 0:41 | 3:48 | 5.6x slower |
| 20 µm | 1:29 | 6:12 | 4.2x slower |
| 10 µm | 2:39 | 13:27 | 5.1x slower |
| 5 µm | 4:16 | 13:46 | 3.2x slower |
| 2 µm | 6:31 | 9:31 | 1.5x slower |
Times in minutes:seconds per gallon. N.B. Oler filter flow testing, 2023.
Recommended micron rating by position
| Position | Micron rating |
|---|---|
| Material columns | 50 and 20 µm |
| Color remediation column | A mixture of 10, 5, 2 and 1 µm, stacked in decreasing rating in the direction of flow |
| Molecular sieve | 10 µm on both sides |
Sintered filters are cleaned, not replaced. Keep a second full set so one set runs while the other is in the ultrasonic bath.
Gasket material compatibility
| Material | Butane | Propane | Ethanol | Heptane | Pentane | Hexane | Isopropyl |
|---|---|---|---|---|---|---|---|
| PTFE | A | A | A | A | A | A | A |
| Viton | A | A | B | A | A | A | A |
| Buna-N | A | A | C | A | B | A | A |
| Silicone | D | D | B | D | D | D | A |
A: excellent. B: good, minor effect. C: fair, not for continuous use. D: severe effect, do not use. Room temperature ratings, conservative value printed where published charts disagree. Full matrix and temperature limits in REF-CM-01 Chemical Compatibility.
Cleaning procedure
- Rule of thumb: if the filter will not flow solvent at 15 psig (about 2 atm), it is clogged. Stop and clean it.
- Best performance: clean after every run, before it ever clogs.
- Excessive clogging? Stack larger micron filters above the sintered filter to catch big particles.
Failure to follow the recommended cleaning procedure may void your warranty.
With a bath ultrasonicator (preferred)
- Cease operation of the relevant instrument.
- Equalize pressure up and downstream with atmosphere, gently, under 0.1 psi per second, by controlled venting or dry nitrogen.
- Remove the filter.
- Gently brush off debris with a nylon or soft metal (brass) brush, never harder than stainless.
- Ultrasonicate in a 304/316 stainless compatible lab detergent such as Alconox, per the detergent maker's procedure.
- Blow out with clean compressed air or nitrogen against the direction you flowed media, so debris exits back out the same dull face that caught it.
- Repeat steps 4 to 6 as needed.
Without an ultrasonicator
- Cease operation and equalize pressure as above, under 0.1 psi per second.
- Remove the filter.
- Soak in Alconox or a similar 304/316 compatible detergent for 5 minutes.
- Gently brush off debris with a nylon or brass brush. Welding shops and gas suppliers carry them.
- Blow out with clean compressed air or nitrogen against the direction you flowed media.
- Repeat as needed.
Isopropyl alcohol, deionized water or both work for light cleaning instead of detergent.
Flow rate data, clean discs
| Micron | 4" filter | 6" filter |
|---|---|---|
| 50 µm | 0:31 | 0:31 |
| 20 µm | 0:50 | 0:36 |
| 10 µm | 1:53 | 1:18 |
| 5 µm | 3:10 | 2:18 |
| 2 µm | 3:48 | 2:49 |
| 1 µm | 4:25 | 3:36 |
Minutes:seconds for one U.S. gallon of cold tap water. If your disc is at or faster than the table, it is clean and ready to use.
How flow rate was tested
- 6" sight spool, caps over the sight glass holes, disc clamped at the bottom on Buna gaskets, raised a couple of inches for drainage.
- Pour 1 U.S. gallon of cold tap water onto the filter and time from first contact until no visible puddle remains. Discs were tested dull side up, the same orientation used in operation.
- For small microns, pour slow and steady to hold a consistent water level. Filters may slow with additional gallons, depending on your local water.
- Test filters were cleaned 20 minutes per side in a 50°C (122°F) ultrasonic bath with 8 to 12 tablespoons of Alconox.
Sources. N.B. Oler Sintered Filter Tech Specs, Rev. 2026.1; N.B. Oler filter flow test data (2023); 3P Certz DCR-200101-R1. Alconox, Inc., Alconox Technical Bulletin (2018). Cole-Parmer Chemical Compatibility Database. Omegasonics, Ultrasonic Cleaning 101. Gasket ratings per N.B. Oler REF-CM-01 (Parker, Trelleborg, Chemours, ISM).