Tri-Clamp Filter Plate (Perforated Plate) with 2x Drop-In Rings
ABOUT THIS PART
A perforated 304L stainless plate that drops into a tri clamp column and keeps a packed bed from moving. Two drop-in rings are included with each plate. Four inch is $29.95, six inch is $34.95. This is a bed retention plate, not a filter.
Priced to clear. We had a large run made to our own drawing and we would rather they were in columns than on our shelf. Comparable drop-in plates with rings sell for $36 to $89 depending on size and seller.
Specification
| 4 inch | 6 inch | |
|---|---|---|
| Price | $29.95 | $34.95 |
| Plate diameter | 3.765 in | 5.704 in |
| Plate thickness | 0.115 in nominal | 0.115 in nominal |
| Hole diameter | 0.125 in | 0.188 in |
| Hole count | 193 | 193 |
| Open area | 21 percent | 21 percent |
| Narrowest metal between holes | 0.066 in | 0.099 in |
| Ring wall | 0.1975 in | 0.1975 in |
| Shipping weight | 2 lb | 3 lb |
Our own design, drawings NB-4-PERF-PLTE-A and NB-6-PERF-PLTE-A, 304L stainless with a 2B finish. The hole pattern is eight concentric rings, 1, 8, 16, 24, 24, 32, 40 and 48 holes from the center outward, with ring spacing at exactly twice the hole diameter.
Why the holes are small, and why that matters
Look at the third photo. The two bright plates are ours, 6 inch and 4 inch. The dull plate at the bottom is a competitor's 4 inch, sitting on our bench for comparison. Same nominal size, far fewer holes, and every one of them noticeably bigger.
That is the whole argument for this plate, and it is about the paper, not the steel. The filter paper has to bridge every hole unsupported. A commodity plate drilled 6 mm leaves the paper spanning 0.236 in. Ours leaves it spanning 0.125 in on the 4 inch and 0.188 in on the 6 inch. Bending stress in a bridged membrane goes with the square of the span, so a 6 mm hole puts roughly three and a half times the stress on the same sheet of paper as our 4 inch pattern does.
That is why people ring us about paper blowing out. It is not bad paper. It is too much unsupported span, and once the paper goes you are picking material out of your outlet for the rest of the run.
- More holes, not bigger ones. 193 holes on both sizes, laid out as eight concentric rings with ring spacing at exactly twice the hole diameter. Open area still comes out at 21 percent, so you are not trading flow for support, you are getting the same open area spread over more, smaller openings.
- Less hang-up. Spreading the same open area across 193 holes distributes flow more evenly across the face of the bed, instead of pulling hard through a few big ports and leaving dead material between them.
- Less paper torn on assembly. Smaller holes mean smaller burr edges to catch a sheet when you are seating it with a gloved hand in a cold column.
Hole sizes above are from our own drawings, NB-4-PERF-PLTE-A and NB-6-PERF-PLTE-A. The 6 mm figure is the common commodity drilling; we have not put calipers on the plate in the photo, so take that one as what it looks like rather than a measurement.
Where it goes, and it is not the same in both columns
This is the part most people get wrong, so here it is plainly. The material column uses one plate, at the bottom. The color remediation column uses two, one at each end, and both ends are built the same way as a material column bottom. They are doing different jobs.
Material column, one plate at the bottom
Built from the bottom up:
- Sintered disc, 50 micron, dull side up toward the material.
- Perforated plate.
- Filter paper.
- Two drop-in rings.
- Pack your material on top.
The plate carries the paper. Paper on its own over an open disc has nothing to sit on and tears through under differential pressure, and then you are picking material out of your outlet.
Color remediation column, two plates, one at each end
Built from the bottom up:
- Sintered discs at the outlet, a 5 micron with a 1 micron below it, each dull side up.
- Perforated plate.
- Filter paper.
- Two drop-in rings.
- Pack your media.
- Perforated plate on top of the media.
- Filter paper.
- Two drop-in rings, for weight.
- A 10 micron sintered disc on top, dull side up.
The bottom of the column is built exactly like the bottom of a material column, just on finer discs. The top plate and the rings are there to hold the bed compressed. Activated alumina, carbon and the packaged remediation blends will mix around and channel if the bed is loose, and a column that has shifted mid run is a column that is no longer doing what you packed it to do. The weight on top is what stops it.
The 10 micron disc at the top does two things. It is finer than the 50 micron at the bottom of a material column, so you are filtering harder at this stage, and it caps the bed so media cannot rise into the oleoresin sitting above it.
What it does not do
- It does not filter. There is no micron rating, because perforations are holes in a plate, not a pore structure. Anything small enough to pass a hole will pass.
- If material is reaching your outlet, the answer is the sintered disc, not this plate. The plate's job is to hold the bed and carry the paper.
- No pressure or temperature rating of its own, because it is a loose component inside the tube and carries no differential across it. Your limits are the system's: an N.B. Oler vessel is designed to 93 C (200 F) per 3P Certz DCR-200101-R1, and the system operates to 50 C (122 F). The lowest applicable limit always governs.
Filter paper and cleaning
- A coffee filter works. Lab filter paper, qualitative or quantitative, in a high to medium flow grade, also works. A slow grade fights you for no benefit, because the paper is not doing your filtration.
- Cleaning: brush the cake off, wash in Alconox or a similar 304 and 316 compatible lab detergent, rinse and dry. There is no media to load up, so nothing needs ultrasonicating out of it.
- Inspect the rings for bends each time and replace any that will not sit flat.
Fitment and ordering
- Fits 4 inch and 6 inch tri clamp columns. It drops inside the sanitary tube of its nominal size.
- It does not clamp between two ferrules, and there is no 3 inch or 10 inch.
- How many: one per material column, two per color remediation column. Count your columns before you order.
- Sold as the plate plus two rings. Clamps, gaskets, sintered discs and spools are separate.
SPECIFICATIONS
▦ IN YOUR MANUAL
This part appears in the operator manual that ships with your system. The QR code there links to this page.
◈ REFERENCE FOR THIS PART
COMMON QUESTIONS
Where does the plate actually go?
It depends which column. In a material column you use one, at the bottom: sintered disc 50 micron dull side up, then the perforated plate, then filter paper, then two drop-in rings, then pack your material on top. In a color remediation column you use two, one at each end, and each end is built the same way as that material column bottom: sintered discs 5 micron over 1 micron at the outlet, perforated plate, filter paper, two drop-in rings, pack your media, then a second perforated plate, filter paper and two drop-in rings, with a 10 micron sintered disc on top.
Why is there a plate on top of CRC media but not on top of material?
Weight. Activated alumina, carbon and the packaged remediation blends will mix around and channel if the bed is loose, and a column that has shifted mid run is no longer doing what you packed it to do. The top plate plus the two rings hold the bed compressed. Packed material does not need that.
What is the 10 micron disc at the top of the CRC for?
Two things. It is finer than the 50 micron at the bottom of a material column, so you are filtering harder at this stage, and it caps the bed so media cannot rise up into the oleoresin sitting above it.
Why does the plate go under the filter paper rather than over it?
Because the paper has to sit on something. Filter paper laid straight over an open sintered disc has nothing supporting it and tears through under differential pressure, and then you are picking material out of your outlet.
Is a perforated plate the same as a sintered filter?
No, and they are not alternatives. A perforated plate is a retention plate. It holds a packed bed in place and carries the filter paper. It has no micron rating and it does not filter. A sintered disc is a manufactured filter element, rated from 1 to 50 micron, and it is what actually does the size exclusion. Every column runs both.
Which one do I need?
If your bed is channelling, settling or moving during a run, you need the perforated plate. If material is coming through to your outlet, you need a sintered disc. If you are building a column from scratch, you need both.
How many do I need?
One per material column. Two per color remediation column, one at each end.
What micron sintered disc goes with it?
50 micron at the bottom of a material column. On a color remediation column, a 5 micron with a 1 micron below it at the outlet, and a 10 micron on top of the stack. Dull side up on all of them, because the dull face has the smaller pores and holds particulate at the surface instead of letting it pack deep into the media.
How many holes does it have?
193, in both sizes. The 4 inch is drilled 0.125 inch and the 6 inch 0.188 inch, both in the same eight ring pattern. Open area is 21 percent on both.
Why are the holes so small?
Because filter paper has to bridge every hole it covers. A smaller hole is a shorter unsupported span, so the paper deflects less under differential pressure and is far less likely to tear through. Most plates on the market are drilled 6 mm, which is 0.236 inch. Ours are 0.188 inch on the 6 inch plate and 0.125 inch on the 4 inch, so the paper is spanning 20 to 47 percent less. We put the flow back by using more holes, which is why open area is still 21 percent. Your media sets the flow rate, not this plate.
What filter paper should I use?
You do not need anything special. A coffee filter works and plenty of people run them. If you would rather use lab filter paper, qualitative and quantitative both work, and you want a high to medium flow grade. A slow grade restricts the run for no benefit here, because the paper is not doing your filtration, the sintered disc is.
What micron is the perforated plate?
It does not have one. Perforations are holes in a plate, not a pore structure, so there is no micron rating to quote. Anything small enough to pass a hole will pass.
What are the two rings for?
Weight and spacing. They sit on top of the stack and hold it down so nothing lifts or shifts once the column is packed and running. On a color remediation column that is their main job.
Who makes these?
N.B. Oler designed them and they are built to our drawings in 304 stainless, drawing numbers NB-4-PERF-PLTE-A and NB-6-PERF-PLTE-A.
Does it clamp between two ferrules?
No. It drops inside the tube. The 4 inch plate measures 3.765 inches across and the 6 inch measures 5.704 inches, both smaller than the tube they go into. A sintered disc is the part that clamps between ferrules, because it is welded into its own tri clamp ring.
What is it made of?
304 stainless, 2B finish, 0.115 inch nominal thickness.
What temperature and pressure is it rated for?
The plate is a loose component inside the tube and carries no pressure across it, so it has no rating of its own. Your limits are the system's: an N.B. Oler vessel is designed to 93 C, which is 200 F, and the system operates to 50 C, which is 122 F. The lowest applicable limit always governs.
How do I clean it?
Brush the cake off, wash in Alconox or a similar detergent rated for 304 and 316 stainless, rinse and dry. There is no media to load up, so nothing needs ultrasonicating out of it. Check the rings for bends every time and replace any that will not sit flat.
Do you sell a 3 inch or a 10 inch?
No. Four inch and six inch only.
Is this the same as a bed retention plate?
Yes. Perforated plate, perf plate, bed retention plate, media retention plate and drop-in plate are all the same part.