KOKEN LTD.
Koken 1521 Series Dust Mask
Manufacturer: KOKEN LTD.
Model: 1521 Series
Important points when wearing a mask
Dust masks utilize high-efficiency filters to effectively prevent the inhalation of hazardous particles. To protect yourself from inhaling particles while wearing a dust mask, both the performance of the filter and the “tight seal” (fit) between the mask and your face are critical.
1. Filter Technology with High Particle Collection Efficiency
Mighty (Uni) Micron Filter
Through unique technology, wool fibers are electrostatically charged, allowing electrostatic force to draw particles to the fiber surface. This is the primary mechanism for collecting particles. A high-density fiber structure is unnecessary, successfully integrating the two contrasting features: “high collection efficiency” and “low inhalation resistance.” It consistently maintains the highest standard of performance and quality, making it an excellent long-term filter solution.
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Applied products are on P.4 ~ 6, P.11
Alpha Ring Filter
Increasing the fiber density of the filter enhances collection efficiency. To meet airflow resistance standards, paper filters traditionally require an expanded surface area.
For the first time in Japan, ultra-fine fibers were formed into pristine circular shapes in a single process, creating the Alpha Ring filter. Today, this filter continues to succeed in expanding the surface area while maintaining a compact shape, significantly reducing airflow resistance.
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Applied products are from page P.8 to P.11
Dust Respirator Standards
In addition to JIS standards, dust respirators are tested according to assay standards based on national regulations. These standards are comprehensive, ensuring that products meeting strict safety requirements are manufactured.
| Dust Respirator Standards | In addition to JIS standards, dust respirators are tested according to assay standards based on national regulations. These standards are comprehensive, ensuring that products meeting strict safety requirements are manufactured. |
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Note: The table below is excerpted from the “Dust Respirator Standards”.
| Replaceable Dust Respirator | Isolation Type Dust Respirator |
|---|---|
| Direct-Connection Type Dust Respirator | |
| Disposable Dust Respirator | |
| Test Particles | Type | NaCl (Sodium Chloride) | DOP (Dioctyl Phthalate) | ||
|---|---|---|---|---|---|
| Particle Size | 0.06 μm to 0.1 μm | 0.15 μm to 0.25 μm | |||
| Concentration | 50mg/m³ or less | 100mg/m³ or less | |||
| Test Flow Rate | 85 ℓ /min | 85 ℓ /min | |||
| Collection Efficiency (Measured continuously; must meet right-column values) | NaCl Test Particles Load up to 100mg | DOP Test Particles Load up to 200mg | |||
| Replaceable Type | RS1 | 80.0% or higher | RL1 | 80.0% or higher | |
| RS2 | 95.0% or higher | RL2 | 95.0% or higher | ||
| RS3 | 99.9% or higher | RL3 | 99.9% or higher | ||
| Disposable Type | DS1 | 80.0% or higher | DL1 | 80.0% or higher | |
| DS2 | 95.0% or higher | DL2 | 95.0% or higher | ||
| DS3 | 99.9% or higher | DL3 | 99.9% or higher | ||
| Inhalation Resistance (Test flow rate 40 ℓ /min) | Replaceable Type | Disposable Type | |||
| RS1 RL1 | 70Pa or less | DS1 DL1 | 60Pa or less (45Pa or less) | ||
| RS2 RL2 | 80Pa or less | DS2 DL2 | 70Pa or less (50Pa or less) | ||
| RS3 RL3 | 160Pa or less | DS3 DL3 | 150Pa or less (100Pa or less) | ||
| Exhalation Resistance (Test flow rate 40 ℓ /min) | Replaceable Type | Disposable Type | |||
| RS1 RL1 | 70Pa or less | DS1 DL1 | 60Pa or less (45Pa or less) | ||
| RS2 RL2 | 70Pa or less | DS2 DL2 | 70Pa or less (50Pa or less) | ||
| RS3 RL3 | 80Pa or less | DS3 DL3 | 80Pa or less (100Pa or less) | ||
Values in ( ) refer to products without an exhalation valve.
| Exhalation Valve Airtightness | Airtightness performance test for the exhalation valve | – Internal pressure must drop immediately when air is drawn. – Time for internal pressure to return to normal atmospheric pressure must be 15 seconds or more. |
|---|---|---|
| Carbon Dioxide (CO2) Concentration Increase | Measured using a test headform and artificial lung to inhale/exhale CO2-enriched air. The difference in CO2 concentration in inhaled air with and without the mask must be 1.0% or less. | |
| Dead Space | Value calculated from the (CO2 Concentration Increase Test). | |
| Inhalation Resistance Increase Value | Test Particles | NaCl (Sodium Chloride) |
|---|---|---|
| Test Flow Rate | Measured at 40 ℓ/min after loading test dust at 85 ℓ/min. | |
| Amount Loaded onto Dust Mask | 100mg |
Test Particles & Collection Efficiency Disposable Type | S | L | Classification (Collection Efficiency) | |
|---|---|---|---|---|
| Solid NaCl Test Particles | Liquid DOP Test Particles | |||
| R | Replaceable Dust Mask | RS1 | RL1 | Class 1 (Above 80.0%) |
| RS2 | RL2 | Class 2 (Above 95.0%) | ||
| RS3 | RL3 | Class 3 (Above 99.9%) | ||
| D | Disposable Dust Mask | DS1 | DL1 | Class 1 (Above 80.0%) |
| DS2 | DL2 | Class 2 (Above 95.0%) | ||
| DS3 | DL3 | Class 3 (Above 99.9%) | ||
High Performance Filter + Ergonomic Face Seal
2. Facepiece Fit Technology
Even if a dust mask has a high collection efficiency filter, it is ineffective if dust leaks through the seal between the face and the mask. The primary cause is the “gap at the facial contact area.” We consider mask fit to be as important as filter performance. Therefore, our company developed technology to enhance the airtightness of the facepiece seal early on.
Silicone Facepiece
Silicone is a hypoallergenic material that is gentle on the skin. Its surface is flexible and effortlessly adapts to facial movements, ensuring a comfortable fit. The material is also stable during long-term use.
HAWC harness strap
The strap design ensures high tension and maximizes the “suction” effect when wearing the mask, ensuring an airtight facial seal. 
Freeposition Underchin
The unique curve of the facial contact area prevents dust entry. By aligning the nose section first, it accommodates various facial dimensions, providing a secure fit for a wide range of face sizes (see image below).
Fit Status of the Freeposition Underchin Mask
(Cross-sectional simulation to show the contact position between the mask and the chin).
| For large faces: The outer section of the mask adjusts the fit around the chin. |  | For small faces: The inner section of the mask adjusts the fit around the chin. |  |
| FF Lip | Wearing Stability | Built-in Fit Checker | |||
|---|---|---|---|---|---|
 | The cushion naturally conforms to various face shapes and sizes for a seamless fit. |  | Uses a 3D-shaped polyband harness that contours to the head, enhancing fit and sealing performance. |  | Built-in fit checker allows you to test the mask’s seal at any time (available for 1005, 1010A, 1015, 1180 series). |
Replaceable Dust Mask – Alpha Ring Filter
Alpha Ring Filter with concentric design and compact shape
Paper filters that enhance particle collection efficiency by increasing fiber density traditionally require an expanded surface area to meet airflow resistance standards.
The Alpha Ring filter was the first domestically developed filter using ultra-fine fibers molded into a round pleat structure.
By continuing to expand the filtration surface area, the filter maintains a compact shape while achieving lower breathing resistance, resulting in higher and more stable performance.
All Alpha Ring filters are water-repellent treated
The filter is treated for water repellency to limit the adherence of mist or droplets, ensuring breathing remains easy during use.
Additionally, this treatment is effective against oil mist.
HAWC Lip (High Adaptable Wide Concave)
The facial contact area has a wide concave surface that surrounds the face. When the harness is tightened, a suction effect is created, resulting in high airtightness.
*HAWC stands for High Adaptable Wide Concave
*Image shown is the Model 1021H.
(Head Harness Types)
Please replace head straps periodically.
Sakai Model 1521H
Durable silicone facepiece, easy to clean
Model Assay Certificate: TM534
Assigned Protection Factor: 50 (RL3)
Also applicable for use as a gas mask (1521HG · Class L3)
(Model Assay Certificate: TN399)
Note: Absorbent canisters are sold separately.
- Silicone Construction
- HAWC Lip
- Speaking Diaphragm
- Spatter-shielding Surface
| Particle Collection Efficiency | 99.9% or higher (Average 99.99%) |
|---|---|
| Inhalation Resistance | 115Pa or less (Average 90Pa) |
| Exhalation Resistance | 45Pa or less (Average 33Pa) |
| Resistance Increase | ― (Average 108Pa) |
| Weight | 625g or less (Average 595g) |
| Head Harness | Type H-VII Rubber Harness |
Replacement Parts
- Inhalation Valve: Type 29
- Partitioned Inhalation Valve: Type NC2
- Exhalation Valve: Type T-6K
Sakai Model 1521U
High-safety full-face mask, suitable for nanomaterials
Model Assay Certificate: TM675
Assigned Protection Factor: 50 (RL3)
The particle collection efficiency reaches 99.999% (average value), meeting high safety requirements for handling nanomaterials.
The full-face design combined with the HAWC Lip creates an exceptional airtight seal, significantly enhancing protection levels.
- HAWC Lip
- Speaking Diaphragm
- Anti-fouling Surface
- Silicone Facepiece
| Particle Collection Efficiency | 99.99% or higher (Average 99.999%) |
|---|---|
| Inhalation Resistance | 137Pa or less (Average 98Pa) |
| Exhalation Resistance | 60Pa or less (Average 33Pa) |
| Resistance Increase | ― (Average 112Pa) |
| Weight | 625g or less (Average 589g) |
| Head Harness | Type H-VII Rubber Harness |
Notes on Filter Replacement
As dust accumulates in the filter, breathing resistance increases, making respiration more difficult.
Furthermore, besides difficult breathing, if the mask does not fit perfectly against the face, dust can bypass the filter through any gaps.
- Always perform a seal check before use and ensure the mask is firmly secured to your face.
- Replace the filter before breathing becomes difficult to prevent excessive resistance buildup.
*If you have any questions regarding replacement, please contact our office or local agent.
Replacement Filters · Optional Accessories
| RD-6 (For: 1721H, 1521H, 7121R, 7191DK) | RD-6U (For: 7191DKU, 1521U) | RD-8 (For: 1180H) | LAS-52 (For: 1781DW) | LAS-52C (For: 1781DWC) | (Optional) Fit Tester – Type V Applied models: 1721H, 1521H, 1521U, 7121R, 7191DK, 7191DKU | (Optional) Fit Tester – Type F Applied models: 1781DW, 1781DWC |
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| 2 pcs/set — Threaded | 2 pcs/set — Threaded | Threaded | 2 pcs/set — Threaded | 2 pcs/set — Threaded |
- Fit Checker: Simply operate the lever to perform a user seal check (fit test).
- Under-Chin: Unique curve enhances the airtight seal between face and mask.
- Silicone: Soft, skin-friendly material; silicone facepiece ensures comfortable long-term wear.
- HAWC Lip: Achieves high airtightness via “suction effect”; applied to full-face models.
- Size S available: Size S options for users with petite faces.
- Low breathing resistance: Employs Alpha Ring filter technology for reduced breathing effort during long shifts.
- Speaking Diaphragm: Integrated device enables clear verbal communication while wearing the mask.
- Activated Carbon: Effectively neutralizes low-concentration ozone; utilizes carbon-impregnated filters.
- Surface Hardening: Visor lens is treated to resist scratches.
- Special Surface Hardening: Advanced coating provides superior scratch protection over standard treatments.
Note: Consumable components and filters should be replaced promptly according to the maintenance schedule.
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