KOKEN LTD.
Koken 1111-03 Dust Mask

Manufacturer: KOKEN LTD.
Model: 1111-03
Important points when wearing a mask
Dust masks utilize high-efficiency filters to effectively prevent the inhalation of hazardous particles. To protect yourself 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
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. |
|---|
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 | |||
| Nồng độ | 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 particles Load up to 100mg | For DOP 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 ( ) are for products without an exhalation valve.
| Exhalation Valve Airtightness | Exhalation valve leak test | – Internal pressure must drop immediately during suction. – Time for internal pressure to return to normal must be 15 seconds or more. |
|---|---|---|
| CO2 Concentration Increase | Measured using a test headform and artificial lung. 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 | Test Particles | NaCl (Sodium Chloride) |
|---|---|---|
| Test Flow Rate | After dust accumulation at 85 ℓ/min, measurement is taken at 40 ℓ/min. | |
| Dust Accumulation Amount | 100mg |
Test Particles & Efficiency Disposable / Replaceable | S | L | Classification (Efficiency) | |
|---|---|---|---|---|
| Test particle: Solid NaCl | Test particle: Liquid DOP | |||
| R | Replaceable Dust Respirator | RS1 | RL1 | Class 1 (≥ 80.0%) |
| RS2 | RL2 | Class 2 (≥ 95.0%) | ||
| RS3 | RL3 | Class 3 (≥ 99.9%) | ||
| D | Disposable Dust Respirator | DS1 | DL1 | Class 1 (≥ 80.0%) |
| DS2 | DL2 | Class 2 (≥ 95.0%) | ||
| DS3 | DL3 | Class 3 (≥ 99.9%) | ||
High Efficiency Filter + Face-Friendly Surface
2. Surface Engineering for a Better Facial Fit
Even if a dust mask has a high collection efficiency filter, it is useless if dust leaks in through the facepiece seal. The primary cause of leakage is the “gap at the contact area when wearing the mask.” We consider the fit of the mask to be as important as the filter performance. Therefore, our company has developed technology to enhance the airtightness of the facial contact area.
Silicone Facepiece
Silicone is a hypoallergenic material that is gentle on the skin. Its surface is flexible and easily adapts to body movements, ensuring wearing comfort and stability during use.
HAWC Harness
The harness design ensures high tension and maximizes the “suction” effect when wearing the mask, guaranteeing an airtight seal on the face.
Freeposition Under-Chin
The special shape of the facial contact area prevents dust entry. The nose section is adjustable for different sizes, ensuring a perfect fit for a wide range of facial dimensions (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 Safety | 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. | ![]() | Built-in fit checker allows for seal checks at any time (for models 1005, 1010A, 1015, 1180 series). |
Headband Types
Please replace headbands on a regular basis.

KOKEN LTD. Model 1111-03
A protective mask with a double-layered structure for exhaust valve protection.
Test Certification: Model Standard TM208
Protection Factor: 10
Key Features: Lightweight design weighing only 88g, providing efficient protection for the facial area.
Replacement Filter: LAS-11

- Facepiece gasket
- Silicone material
- Low inhalation resistance
Options:
- Fit Tester Type G
- Moisture Sponge Type A
| Particle Collection Efficiency | 95.0% or higher (Average 98.5%) |
|---|---|
| Inhalation Resistance | 80Pa or less (Average 63Pa) |
| Exhalation Resistance | 55Pa or less (Average 32Pa) |
| Inhalation Resistance Increase | ― (Average 131Pa) |
| Weight | 104g or less (Average 88g) |
| Harness | RB Type |
Replacement Accessories:
- Inhalation Valve: Type 36
- Exhalation Valve: Type T-6K
▲ Shared Replacement Parts for 6 Models (1181R-03, 1121R-08, 1191SD-03, etc.)
- Inhalation valve: circular type
- Moisture sponge: oval type
- Replacement filters · Accessories (optional)
| LAS-52 (for Model 1181R) | LAS-52C (for Model 1181RC) | LAS-1 (for Models 1121R, 1121RX, 1191SD, 1191D) | LAS-51 (for Model 1180) | LAS-51C (for Model 1180C) | KBC Filter for 1121 / 1191 (Ozone and organic odor removal – pack of 5) For models: 1121R / 1121RX / 1191SD / 1191D / 1122R (Optional) | Fit Checker – Type F For models: 1181R, 1181RC, 1121R, 1121RX, 1191SD, 1191D (Optional) |
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| Screw-on – pack of 2 | Screw-on – pack of 2 | Pack of 2 | Screw-on – pack of 2 | Screw-on – pack of 2 |
- Under-Chin design: Special curved shape improves seal at the facial contact area.
- Silicone: Soft, skin-friendly material for a comfortable fit. The mask uses a silicone seal.
- Size S Available: Size S is available for users with smaller faces.
- Low Inhalation Resistance: Uses Alpha Ring filters with low breathing resistance, suitable for long work hours.
- Speaking Diaphragm: Allows communication and commands without removing the mask.
- Activated Carbon: Simultaneously removes low-concentration ozone with activated carbon filters.
- Micron: High-efficiency electrostatic filter material, compatible with RL ratings.
- Fit Checker: Perform a fit test easily using the manual lever.
Double-Layer Bonnet Structure The exhalation valve is positioned inside the bonnet, shielding it from external factors like wind. | ![]() |
| Note on Replacement Always replace consumable parts like filters early as recommended. |




























