Delivering Fluid Sealing Solutions Since 1972

Mixers and Vessels Seals

Mixer and Vessels Seals: Encapsulated Seals, Lip Seals, Mechanical Seals, and Packing Seals

M Barnwell Services is one of the UK’s leading stockists and distributors of Pharmaceutical seals and can provide specialist Mixers and Vessels Seals to meet all internal applications. With over £5.1 million in stock, we serve over 5000 global customers with swift and dependable deliveries.

Our proficient team manages the entire production process, from prototyping and testing to final part manufacturing. Additionally, we offer specialised certification upon request.

If you would like more information about our range visit the Pharmaceutical Overview Products page or contact a team member.

Mixers and Vessels Seals

The significance of environmental and process factors in mixer design is significant, paralleling the importance of mechanical aspects. Our solutions approach surpasses mere mixer applications, encompassing process, environment, and pressure specifications for optimal configuration.


  • Mechanical
  • Packing
  • Double Lip Seal
  • Cost / Performance

Seal challenges include reducing operating heat, minimising seal and shaft wear, lowering power consumption, and mitigating parasitic friction. Brief descriptions of each seal type are provided below. Our agitator design choices include Encapsulated Seals, Lip Seals, Mechanical Seals, and Packing Seals.

Encapsulated Seals in Mixers and Vessels

When searching for top-tier Encapsulated O Rings, it’s crucial to understand key considerations. Amid numerous choices, the allure of lower prices or captivating marketing can be tempting. Yet, for vital applications like Nuclear or Medical sectors, the seal’s selection significantly impacts reliability and cost efficiency.

The specialist NCAP™ Encapsulated Seal is a premier product with a track record of lasting thrice as long as lower-quality Encapsulated Seals. NCAPs™ offer cost-effective advantages to makers of sizable mixers and vessels by eliminating the need for tooling during production for lid seals. Their FDA compliance also positions them as a perfect choice for the burgeoning Pharmaceutical sector.

Recognising the uniqueness of each project, we provide a diverse range of customised Encapsulated O Rings. For more details, contact us.

Industrial Agitators and Lip Seals

Lip seals are designed to maintain fluids or manage lower pressures, ensuring the mixer functions optimally. Additionally, they serve as a cost-effective barrier against contaminants entering the mixing vessel. Effective lip seals must consistently engage the rotating element, such as the mixer shaft.

Successful lip seal performance relies on appropriate material choice, installation, and upkeep. Proper initial installation is vital to prevent leakage while adhering to a maintenance regimen enhances its durability.

In sectors such as Chemical Processing, Pharmaceutical, Pulp and Paper, and Food and Beverage, maintaining adherence to industry standards, preventing contamination, and optimising efficiency in mixers and vessels are perpetual focal points.

Pressure becomes a factor of consideration when mixing in enclosed tanks, which makes selecting the appropriate seal to manage this pressure crucial, as pressure naturally moves from high to low.

For scenarios with high pressure, lip seals are less suitable, performing better in low-pressure mixing conditions. A favorable alternative includes packing seals, which are adept at handling high vessel pressure while remaining cost-effective.

Visit our Agitators and Mixer Seals Page for more information.

Mixers and Vessels Seals 2

Mechanical Seals in Mixers and Vessels

Mechanical seals are a necessity when there’s zero tolerance for seal pressure and vapor leakage. Though they involve a higher initial cost, their long-term benefits are unmatched.

  • Surpass packing seals and stuffing box seals in efficiency.
  • Mechanically sealed mixers and vessels consume less power than those using packing seals.
  • Minimise maintenance needs by substantially reducing leaks and contamination risks.
  • Alleviate wear on the connecting shaft or sleeve.
  • Explosion-proof applications.

When dealing with toxic or volatile mixing environments, where fluid lubrication poses a risk, mechanical seals emerge as the optimal choice. This is especially true when volatile dust or vapors are present.

Considering your specific application, certain configuration choices might be necessary for mechanical seals, which can be set up in various ways: Single vs. Double Mechanical Seals and Solid vs. Split Mechanical Seals.

Single Mechanical Seals are common in most mixer setups, while Double Mechanical Seals find utility in the Pump Industry where fluid contacts the motor. Double seals enhance security against contamination.

Choosing between Solid and Split Mechanical Seals often hinges on factors like maintenance, accessibility, and cost. Split seals are notably pricier than Solid ones but offer easy maintenance without motor removal. Despite the higher upfront cost, they save production downtime and maintenance expenses.

In summary, while mechanical seals entail an initial investment, we recommend them for explosion-proof, high-risk contamination, and convenient maintenance scenarios, much like Split mechanical seals.

Industrial Agitators and Packing Seals

Packing seals are a historic technology, tracing back to miners using socks for leakage control. Today, safer and more modern materials are used.

They find extensive application and consist of rope-like material surrounding mixer shafts to reduce fluid loss. Economically compared to mechanical seals, they inherently have a continuous lubricant leak between the shaft and packing.

Like lip seals, the choice of proper packing material hinges on application factors like temperature, pressure, and components. Industries vary in their preference for packing seals; Heavy Industries, for instance, often opt for them due to their forgiving nature.

For more information about our Approved Materials, click here.

You Are In Safe Hands

As a trusted supplier to leading global OEM manufacturing companies, M Barnwell Services is committed to providing superior products and an exceptional level of service that rivals, if not surpasses, all others.

With a sealing inventory exceeding £5.1 million and supported by five strategically located branches throughout the UK, we are perfectly positioned to meet your requirements and strive to exceed your expectations.

For further details about our offerings, access our catalogue or contact a member of the team.



No limitation to dimensions with customisation available.


Fluoropolymers that meet FDA, USP, 3A, EU1335, FEP/PFA/Tefzel standards.

Nitrile (NBR), Viton® (FKM/FPM), Ethylene propylene (EPDM), EnDura™ (Steam Resistant), Silicone (VMQ), Fluorosilicone (FVMQ), ), Viton® A, Viton® B, Viton® GF, Viton® GLT, Viton® GFLT, Viton® ETP.


British Imperial (BS1806) and Metric (BS4518). European Metric (ISO 3601), including German (DIN 3771), Swedish (SMS 1586/1588) and French (NFT 47 501). American (SAE, AMS, AS568) and Japanese Metric (JISB 2401), SAE J515 and ISO8434-3 (SAE O ring boss hydraulic adaptors).


WRC, WRAS, FDA, DVGW, KTW, BGVV, KIWA, USP Class VI, NSF, ACS, EU2002/72, EN681-1, EN549, 3A Sanitary, NORSOK and EN682 and many more

Associated Products

Encapsulated O-Rings (FEP/PFA), Lube, Gauge / O Ring Material Tester, Quad Rings® (X-Rings) / Nu-Lip Rings, Mechanical Seals, O-Ring Cord, Tube, Anti-Extrusion Rings, Splicing Kits, Back-Up Rings, Anti-Extrusion Rings, Lubricants and Adhesives.