KOKEN LTD.
Koken 1721H-03 Dust Mask
Manufacturer: KOKEN LTD.
Model: 1721H-03
Important Points When Wearing a Respirator
Dust masks utilize high-efficiency filters to effectively prevent the inhalation of hazardous particles. To protect yourself from inhaling dust while wearing a respirator, both the performance of the filter and the “tight seal” (fit) between the mask and the face are critical.
1. Filter Technology with High Particle Collection Efficiency
Mighty (Uni) Micron Filter
Using unique technology, wool fibers are electrostatically charged, allowing electrostatic force to draw particles to the fiber surface. This is the primary mechanism for capturing 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 | |||
| Particle Collection Efficiency (Continuous measurement; must meet values in the right column) | For NaCl test aerosol Loaded up to 100mg | For DOP test aerosol Loaded 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) | ||
( ) indicates products without an exhalation valve.
| Exhalation Valve Airtightness | Exhalation valve operation leak test | – When air is drawn, the internal pressure must decrease immediately – The time for internal pressure to return to normal atmospheric pressure must be 15 seconds or more |
|---|---|---|
| Carbon Dioxide (CO2) Concentration Increase | Using a test headform and an artificial lung to inhale/exhale air containing CO2. The difference in CO2 concentration in the inhaled air between wearing and not wearing the mask must be 1.0% or less. | |
| Dead Space Volume | Calculated from the (Carbon Dioxide Concentration Increase Test) | |
| Inhalation Resistance Increase | 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 respirator | 100mg |
Test Aerosol and Efficiency Disposable Type | S | L | Classification (Particle Collection Efficiency) | |
|---|---|---|---|---|
| Test aerosol is solid NaCl | Test aerosol is liquid DOP | |||
| R | Replaceable Dust Respirator | RS1 | RL1 | Class 1 (80.0% or higher) |
| RS2 | RL2 | Class 2 (95.0% or higher) | ||
| RS3 | RL3 | Class 3 (99.9% or higher) | ||
| D | Disposable Dust Respirator | DS1 | DL1 | Class 1 (80.0% or higher) |
| DS2 | DL2 | Class 2 (95.0% or higher) | ||
| DS3 | DL3 | Class 3 (99.9% or higher) | ||
High Efficiency Filter + Ergonomic Face Seal
2. Facepiece Fit Technology
Even if a dust mask has a high collection efficiency filter, it is meaningless if particles leak through the seal during use. The primary cause of exposure 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 wearing comfort and stability during use.
HAWC harness strap
The strap design ensures a high level of fit, maximizing the “suction” effect when wearing the mask to ensure an airtight seal on the face. 
Freeposition Under-Chin
The special shape of the facial contact area prevents dust entry. The nose section is aligned first, allowing it to accommodate various facial dimensions and providing a secure fit for a wide range of face sizes (see image below).
Fit Status of the Freeposition Under-Chin Facepiece
(Cross-sectional simulation to show the contact position between the mask and the chin).
| For large faces: Uses the outer section of the mask to adjust the fit around the chin. |  | For small faces: Uses the inner section of the mask to adjust the fit around the chin. |  |
| FF Lip | Wearing Stability | Internal Fit Checker | |||
|---|---|---|---|---|---|
 | Designed for various face shapes; the cushion naturally fits your face. |  | Utilizes a 3D poly-band harness that matches head shapes to enhance the feeling of fit and seal. |  | Fit checker is integrated inside, helping to check the mask seal at any time (available for models 1005, 1010A, 1015, 1180 series). |
Replaceable Dust Respirator – Alpha Ring Filter
Alpha Ring Filter with concentric design and compact shape
Paper filters that enhance particle collection efficiency by increasing fiber density often 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.
Currently, 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.
Sakaki – Model 1721H-03
High-durability protective goggles and facepiece
RL3 Rating
Type Certification: TM646
Assigned Protection Factor: 50
Additionally, it can be used as a gas mask
(Model 1721HG · Class L3)
(Absorbent canisters sold separately)
(Type Certification: TN75)
- HAWC Lip
- Speaking Diaphragm (facilitates communication and commands)
- Hardened visor surface treatment
| Particle Collection Efficiency | 99.9% or higher (Average 99.99%) |
|---|---|
| Inhalation Resistance | 115Pa or less (Average 91Pa) |
| Exhalation Resistance | 60Pa or less (Average 34Pa) |
| Resistance Increase | ― (Average 106Pa) |
| Weight | 554g or less (Average 536g) |
| Head Harness | HV Type Rubber Harness |
Shared Replacement Parts
- Inhalation Valve: circular type
- Partitioned Inhalation Valve: NC type
- Exhalation Valve: T-6K type (white)
Notes on Filter Replacement
As dust accumulates in the filter, breathing resistance increases, making respiration more difficult.
Furthermore, beyond 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 |
 |  |  |  |  |  |  |
| 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: High airtightness achieved through a “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 early and on schedule.
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