3M 4251+ Half Respirator Mask

  • RS Stock No. 189-3493
  • Mfr. Part No. 4251+
  • Brand 3M
Technical Reference
Legislation and Compliance
RoHS Status: Not Applicable
COO (Country of Origin): US
Product Details

3M™ 4251+ Half Mask Reuseable Respirator

Introducing the 3M™ 4251+ series respirator. This is a reusable half-mask respirator that provides lightweight, comfortable and effective protection against particles and vapours. Suitable for a broad range of industrial applications, the innovative comfort features help to ensure that the respirator is worn consistently over long periods.


The 3M™ 4251+ respirator features integrated filters, which then enables the field of view to be undisturbed when being used. An adjustable head cradle helps fit a large variety of head sizes, with additional neck-straps for a more secure fitting. An exhalation valve that helps to direct exhaled breath and moisture downward to avoid fogging up glasses or face shields.

Designed to work well with 3M Eyewear and Hearing Protection products.


• Effective and comfortable protection against organic vapour and hazardous particulates
• A newly enhanced valve assembly helps to reduce exhalation breathing resistance for improved breathing comfort
• Lightweight, well-balanced, low profile design
• Integrated cartridge and filters mean it’s ready to use and maintenance free
• Soft, close-fitting face seal made with textured, non-allergenic material
• Adjustable head cradle and easy to fasten neck straps
• Centrally-positioned exhalation valve helps reduce heat and moisture build-up in hot and humid conditions
• FFA1P2 R D protects against organic vapours, with a boiling point greater than 65 °C, up to 10 x Workplace Exposure Limit (WEL) or 1000 ppm (whichever is lower), and 10 x WEL for particulates
• Includes a resealable bag for hygienic storage and transportation

Maintenance-free and ready to use with two large inhalation valves with permanently attached particulate filters. Delivering protection against organic particles and vapours. Vapours up to 10 x Threshold Limit Value (TLV) or 1000 ppm, whichever is lower and 12 x TLV for particulates.

Features and Benefits

• A ready-to-use half-mask respirator is designed for effective and comfortable protection against organic vapour and particulate hazards
• Respirators can be used until damaged, particulate filters clog, gas filters become saturated or after one month
• Exhalation valve centrally positioned for effective removal of heat and moisture
• Twin inhalation valves with large carbon filters
• Low profile design for better peripheral vision
• Adjustable head cradle and easy to fasten neck straps
• Lightweight, well-balanced design


Filtered respirator facemasks are essential PPE for environments where particle ingress can be potentially hazardous to your health, such as gas, vapours or dust. They are often more suitable for heavy-duty tasks than disposable facemasks. Replaceable respirator particulate filters are graded in different ways to indicate their suitability for different applications, such as;

• A- Organic vapours with a boiling point more than 65°C
• B- Inorganic vapours
• E- Acid gases
• K- Ammonia and ammonia derivatives
• AX- Organic vapours with a boiling point less than 65°C


How long do the filters last?

As particle filters load up with the contaminant they actually become a better filter. However, they become a harder filter to breathe through. The user will notice breathing becoming too hard and will then need to change the filter if able, or replace the mask.

Half-mask or full-mask respirators?

Depending on the health and safety requirements of your workplace or the demands of your application, you may need to choose between a half mask or full mask respiratory. Half mask respirators cover only the nose and mouth, while full masks cover the entire face. While both masks may have the same grade of filter, a full face mask has the benefit of sealing around the whole face, creating a more secure seal. Full face masks also have the advantage of protecting the eyes from vapours or splashing. As such, the full face mask option is often a better choice for potentially more hazardous conditions.

However, a half-mask might be a more cost-effective option if extra protection isn't needed, or might be more suitable for use in combination with specialized headgear.

Correct use of respirators

When it comes to respiratory protection, the correct fitting and testing of your respirator is just as important as selecting the correct respiratory protective equipment for your working conditions. Be sure to follow all pertinent instructions and that health and safety best practice is adhered to at all times. Always be sure to use the correct filters for your environment, and make sure the replacement filters are changed as regularly as is recommended if applicable.

Attribute Value
Type Half Mask
Size One Size
Hypoallergenic No
Includes Replacement Filters No
Series 4000
Colour Blue
700 In stock - FREE next working day delivery available
Price Each
£ 21.97
(exc. VAT)
Per unit
1 +
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