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How to Spec a Custom Die-Cut Filter or Vent: What to Send H-O for a Quote
A fast, accurate quote on a custom die-cut filter or vent comes down to a handful of inputs: the job the part does, the flow and the acceptable pressure drop or the target ingress level, the geometry and open area, the environment, any flammability or biological-contact requirement, the adhesive configuration, your prototype and annual volumes, and a drawing. This guide walks each input, explains why it matters, and ends with a spec builder that assembles your answers into a request you can paste straight into the quote form.
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The application problem: an incomplete spec stalls the quote
H-O Products is a precision die-cut converter, and every filtration and venting part is made to order from sheet, roll, or slab stock cut to your drawing. The concrete problem a buyer runs into is the stalled quote: a request that says "I need a foam filter" without the airflow, the open area, or the particle size to capture cannot be turned into a grade and a price without a follow-up.
The inputs below are the same ones an applications engineer would ask for, so sending them up front turns a back-and-forth into a single response.
The first input does the most work. As covered in the companion guide on choosing between a filter and a vent, the part is either a through-porous filter (let flow through, catch particles), a pressure-equalization vent (breathe, stay sealed against liquid and dust), or a fluid-management pad (absorb and move fluid). The rest of the spec branches from that answer.
Why it is challenging: the inputs come in pairs and the system owns the rating
Specifying these parts is harder than listing dimensions because two of the most important inputs are pairs, not single numbers, and because some results belong to the assembly rather than the part. For a filter, airflow and acceptable pressure drop have to travel together, since a reticulated foam is a depth-loading screen graded in pores per inch (PPI) where capture and restriction rise together: tightening the grade to catch finer particles raises the pressure drop the fan must overcome.
For a vent, the target ingress level and the enclosure volume travel together, because the membrane open area is sized to equalize that specific volume as it heats and cools. And an ingress rating is a result the assembled enclosure earns in a test, not a property of the converted part, so the spec has to separate what the part does from what the system must prove.
The checklist below is organized around those realities.
What to send, input by input
1. The job, and the performance target that goes with it
- If it is a filter: the airflow the part must pass and the acceptable pressure drop, plus the particle size you need to capture. These set the pore grade and the face area. Reticulated foam is a depth-loading filter graded in pores per inch (PPI): lower PPI is coarse and low-restriction, higher PPI is finer at a higher pressure drop, so the grade is a trade between capture and airflow.
- If it is a vent: the target ingress level (for example an IP code) and the enclosure volume, plus how fast the housing heats and cools. The membrane is sized from the open area needed to equalize that volume. Remember the assembled enclosure carries the IP rating; the converted part supports it.
- If it is a fluid pad: the fluid, the volume to take up or move, and whether the contact requires a biologically-evaluated material.
2. Geometry, open area, and thickness
Send the footprint and the open area the part covers, plus the thickness or thickness range. Open area drives both airflow on a filter and equalization rate on a vent. H-O converts shapes up to about 5 inches thick and 60 inches wide by 118 inches long, so most enclosure and device footprints are well inside the envelope. A dimensioned drawing is the cleanest way to convey this (see input 8).
3. Environment: dust, fluid, UV, oils, moisture
The environment selects the grade and the coating:
- UV but not direct weather: an acrylic-coated reticulated foam.
- Outdoor, durable, or wipe-clean: a PVC-coated reticulated foam.
- Humid or mildew-prone: polyether polyurethane chemistry, which commonly offers higher moisture and mildew resistance than polyester.
- Oils or road spray on a vent: an oleophobic-treated ePTFE grade, because a hydrophobic-only membrane resists water but not oils.
4. Flammability requirement
If the part sits inside a flammability-controlled enclosure, say so. A standard filter foam can degrade a flame-rated cabinet's class; a UL 94 HF-1 flame-rated reticulated foam is specified for that case. Name the standard you are designing to (for example UL 94 HF-1) rather than "fireproof," so the right grade is selected.
5. Biological contact
For a fluid-management pad that contacts body fluids, state the contact type. The material is selected in a grade the maker reports as evaluated for the relevant contact under ISO 10993. H-O converts that grade; the finished-device biocompatibility file is owned by the device maker, not the converter, so we will frame the material as evaluated for the contact rather than certifying the device.
6. Adhesive and stack-up
Tell us whether the part needs a pressure-sensitive adhesive on one face, a liner, a pull-tab for line placement, or a laminated stack. A pressure-equalization vent in particular is an assembly: a protective mesh or cap, the ePTFE membrane, a die-cut adhesive ring or carrier, and the enclosure wall. H-O converts the membrane and the die-cut adhesive carrier and can kit the layers for your line.
7. Prototype and annual volume
Share both the prototype quantity and the expected annual volume. All parts are custom manufactured to order, and minimum production run quantities apply, so the volume shapes the converting approach and the tooling decision. Prototype quantities through full production are welcome.
8. The drawing
A dimensioned drawing closes the loop. Send a DXF, STEP, or PDF with the footprint, thicknesses, hole or slot pattern, tolerances, and any adhesive callouts. If you do not have a formal drawing yet, a marked-up sketch with dimensions is enough to start a prototype.
The spec at a glance
| Input | Filter | Vent | Fluid pad |
|---|---|---|---|
| Performance target | Airflow + acceptable pressure drop; particle size to capture | Target IP code + enclosure volume; heat-cool rate | Fluid + volume to absorb or move |
| Geometry | Footprint, open area, thickness | Opening size, mounting footprint | Pad footprint and thickness |
| Environment | Dust, UV, moisture → coating / chemistry | Water, dust, oils → hydrophobic / oleophobic | Contact type |
| Compliance | UL 94 HF-1 if in a flame-rated cabinet | Enclosure IP per IEC 60529 (assembly) | ISO 10993 if body-fluid contact |
| Build | Adhesive, liner, kit | Adhesive ring, mesh, kit | Adhesive, liner |
| Commercial | Prototype quantity + annual volume; drawing (DXF / STEP / PDF) | ||
Filtration & Venting RFQ Spec Builder
Job: Filter (through-porous; pass flow, capture particles) Performance target: airflow + acceptable pressure drop, particle size to capture — to be provided Geometry: footprint / open area and thickness — to be provided Environment: to be provided Compliance: none stated Build: standard die-cut Commercial: prototype quantity + annual volume — to be provided Drawing: to follow
Illustrative only; confirm against current material data and a drawing review. This builder formats your inputs into a request; it does not select a grade, compute airflow or pressure drop, or assign an IP rating. Pore grade, airflow, pressure drop, water-entry behavior, flame classification, and biological evaluation are confirmed on the manufacturer's current technical data sheet and in an H-O drawing review. The IP rating is achieved by the assembled enclosure, not by the converted part.
Common failure modes in the spec itself
| Spec gap | Why it stalls the quote | The fix |
|---|---|---|
| "A foam filter," no airflow | Pore grade and face area cannot be set without the airflow and pressure-drop pair | Send airflow and acceptable pressure drop together |
| Asking for an "IP67 part" | The membrane does not carry an IP rating; the enclosure does | Send the target IP code and enclosure volume; validate IP on the assembly |
| "Fireproof foam" | Not a grade designation; the right flame-rated grade is ambiguous | Name the standard, for example UL 94 HF-1 |
| "Biocompatible foam" | Biocompatibility is a finished-device result; the converter cannot own it | State the contact type; ask for a grade evaluated under ISO 10993 |
| No volumes | The converting and tooling approach depends on prototype versus production scale | Send both prototype quantity and annual volume |
How H-O Products helps
H-O Products is a precision die-cut converter. Once your spec is complete, we recommend a material family and grade direction across reticulated polyurethane filter foam (uncoated, acrylic-coated, PVC-coated, and UL 94 HF-1 grades) and Gore ePTFE venting membrane, then convert the stock to your drawing: die-cut, kiss-cut, laser or waterjet cut, laminated, slit to width, and kitted.
Documentation available on request includes the material technical data sheet, a certificate of conformance, lot traceability, and first-article inspection, all under our ISO 9001:2015 certified quality management system. We do not produce the raw stock and we do not certify the finished enclosure or device; grade properties are confirmed against the manufacturer's current technical data sheet.
Send the spec, get a quote
Use the builder above to assemble your request, then paste it into the quote form with your drawing attached. We will recommend a grade direction and convert samples on your footprint.
Samples typically ship in 3 to 5 business days for common die-cut configurations; standard production runs about two weeks; special orders are quoted to the job.
Family-owned in Winsted, Connecticut since 1971 · ISO 9001:2015 certified · OEMs worldwide send us a drawing — and get back their part.
Related reading
Frequently asked questions
What information does H-O need to quote a custom filter or vent?
Send the job (filter, vent, or fluid pad); for a filter the airflow, acceptable pressure drop, and particle size to capture; for a vent the target IP code and enclosure volume; the footprint, open area, and thickness; the environment (dust, UV, oils, humidity); any flammability (UL 94 HF-1) or biological-contact (ISO 10993) requirement; the adhesive configuration; prototype quantity and annual volume; and a drawing in DXF, STEP, or PDF.
Request a quote for your filtration & venting part
Send H-O your drawing or describe the part—engineering reviews every RFQ and converts samples on your geometry.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
References
- IEC 60529 (degrees of protection provided by enclosures, IP Code). IEC.
- ASTM D3574 (flexible cellular polyurethane) and ASTM D737 (air permeability). ASTM International.
- ASTM D3330 (pressure-sensitive adhesive peel). ASTM International.
- UL 94 (flammability). UL Standards.
- ISO 10993 (biological evaluation of medical devices). ISO.
- Manufacturer technical data sheets: reticulated polyurethane filter foam and Gore ePTFE venting membrane.
This article cites general engineering principles and published standards (IEC 60529 for ingress protection, UL 94 for flammability, ISO 10993 for biological evaluation, ASTM D3574 for flexible polyurethane foam, ASTM D737 for air permeability, ASTM D3330 for pressure-sensitive adhesive peel). Material names refer to material families H-O Products converts.
Pore grades, airflow, pressure drop, and water-entry values are grade-specific; confirm all values against the manufacturer's current technical data sheet and an engineering drawing review.
All parts are custom manufactured to order and minimum production run quantities apply. H-O is a die-cut converter, not a raw-material producer, and does not certify the finished enclosure or device.