We supply double-acting mechanical seals for homogenisers from Vakumix and NETZSCH Vakumix – in all standard sizes from 20 to 45 mm shaft diameter, the special size of 25 mm and for laboratory plants. The seals also fit circulation agitators in pre-phase vessels and are available from us from EUR 2,001.72 net. On request, we fit them for you together with a new shaft.
Compatible – not an original part: Our mechanical seals are bought-in parts from specialised seal manufacturers and fit homogenisers from NETZSCH Vakumix and Vakumix. They are not original parts and this is not an offer from NETZSCH or Vakumix.
Double-acting mechanical seals for Vakumix and NETZSCH Vakumix by homogeniser size
The homogenisers of homogenising mixers are sealed with double-acting mechanical seals. The seal you need depends on the diameter of the homogeniser shaft:
| Homogeniser size | Shaft Ø | Batch size of the plant | Net price |
|---|---|---|---|
| Size 0 | on request | laboratory plants with 2, 5 and 10 litres | on request |
| Size 1 | 20 mm | approx. 15 to 100 litres | EUR 2,001.72 EUR 2,382.05 incl. VAT |
| Size 2 | 24 mm | approx. 125 to 500 litres | EUR 2,574.10 EUR 3,063.18 incl. VAT |
| Size 3 | 30 mm | approx. 600 to 1,500 litres | EUR 3,039.70 EUR 3,617.24 incl. VAT |
| Size 3 with reinforced drive | 35 mm | approx. 600 to 1,500 litres | EUR 3,322.10 EUR 3,953.30 incl. VAT |
| Size 4 | 45 mm | approx. 2,000 to 7,000 litres | EUR 4,079.93 EUR 4,855.12 incl. VAT |
| Special size | 25 mm | on request | on request |
All prices per mechanical seal are net, plus VAT (gross price incl. 19% German VAT below) and shipping of EUR 49.95 per seal (insured express, Germany). The decisive factor is always the shaft diameter of the homogeniser or circulation agitator. Batch sizes are for guidance.
Delivery time approx. 1 week (dispatch after 3–7 working days). Sales exclusively to business customers.
All sizes, prices and materials as PDF (key facts, 1 page)
Product pages by size
Materials and versions
Each mechanical seal consists of a V4A stainless steel housing with four seal rings and built-in O-rings. In the standard version, the seal rings are made of silicon carbide (SiC). SiC is particularly wear-resistant, even with abrasive raw materials. The O-rings are made of FKM as standard; other elastomers such as EPDM are available on request. Depending on the product and application, other material pairings are possible, for example carbon against chrome cast iron. Contact us and we will agree the right version with you.
| Component | Standard | Alternatives |
|---|---|---|
| Housing | V4A stainless steel | – |
| Seal rings (4 pcs.) | Silicon carbide (SiC) | e.g. carbon against chrome cast iron |
| O-rings | FKM | on request, e.g. EPDM |
Also for circulation agitators in pre-phase vessels
The mechanical seals are not only suitable for homogenisers: they can also be used in circulation agitators. These circulation agitators are installed in pre-phase vessels. Here, too, the shaft diameter is decisive – just tell us the size.
Why we also replace the shaft when changing the seal
If the mechanical seal leaks, the homogeniser has to be dismantled and a new seal fitted. The shaft should be replaced at the same time:
- With age, the shaft can become unbalanced.
- The shaft wears in the area of the mechanical seal.
In both cases, a new seal on the old shaft would have a much shorter service life. With a new shaft and a new seal, your homogeniser runs reliably again.
After a crash: replacing rotor, stator and shaft
If a foreign body gets between the teeth of rotor and stator, a crash can occur and the teeth are damaged. In this case rotor, stator and shaft have to be replaced. We supply matching rotor-stator sets and shafts and fit them on request.
What you get from us
Mechanical seals
- Double-acting, compatible with Vakumix and NETZSCH Vakumix
- Shaft Ø 20, 24, 30, 35 and 45 mm, special size 25 mm
- Size 0 for laboratory plants with 2, 5 and 10 litres
- Also for circulation agitators in pre-phase vessels
- Standard: V4A stainless steel housing, SiC seal rings, FKM O-rings
- Other materials on request, e.g. carbon against chrome cast iron or EPDM O-rings
Shafts & rotor-stator sets
- Homogeniser shafts as spare parts
- Rotor-stator sets after a crash
- Matched to the homogeniser size
Barrier fluid & accessories
- Barrier fluid for the seal system
- O-rings and small parts
- Matched to your seal
Seal replacement service
- Dismantling and reassembly of the homogeniser
- Fitting of seal and shaft
- In our workshop or on site
Our service around your mechanical seal
Damage analysis with report
We examine every removed seal. You receive a short report on the damage pattern and the likely cause.
Testing with test report
After repair or fitting, we test the mechanical seal – on request with a test report for your documentation.
Collection & return
We collect your seal by courier and return it to you after repair.
Exchange seal against downtime
With an exchange seal your plant keeps running while we work on the removed seal.
How to order the right mechanical seal
- Determine the size: tell us the shaft Ø, homogeniser size or batch size of your plant.
- Define the scope: seal only, seal with shaft or complete replacement by us.
- Receive a quotation: we get back to you with price and delivery date.
Frequently asked questions about mechanical seals
Which mechanical seal fits my Vakumix homogeniser?
The decisive factor is the diameter of the homogeniser shaft: 20, 24, 30, 35 or 45 mm, or the special size of 25 mm. Laboratory plants with 2, 5 and 10 litres use a separate size 0 seal. Tell us the shaft Ø, homogeniser size or batch size of your plant and we will tell you which seal fits.
Do the seals also fit NETZSCH Vakumix homogenisers?
Yes. Our mechanical seals are compatible with homogenisers from Vakumix and NETZSCH Vakumix in sizes 0 to 4.
Do the seals also fit circulation agitators?
Yes. The mechanical seals can also be used in circulation agitators installed in pre-phase vessels. Here, too, the shaft diameter is decisive.
How much does a mechanical seal cost?
Depending on the shaft Ø, between EUR 2,001.72 (20 mm) and EUR 4,079.93 (45 mm), each net plus VAT and shipping of EUR 49.95 per seal (insured express, Germany). Size 0 and the special size of 25 mm on request.
What materials are the mechanical seals made of?
In the standard version: a V4A stainless steel housing, four silicon carbide (SiC) seal rings and FKM O-rings. SiC is particularly wear-resistant, even with abrasive raw materials. Other seal ring pairings such as carbon against chrome cast iron and O-rings made of EPDM, for example, are available on request.
Are there seals for LambdaVita, KappaVita and GammaVita?
NETZSCH Vakumix names its machines, among others, LambdaVita homogeniser, KappaVita homogenising mixer and GammaVita phase/suspension mixer. The decisive factor for the right mechanical seal is the shaft diameter of the homogeniser. Tell us the machine type, year of manufacture and shaft Ø and we will check the fit.
Do you offer an exchange seal and collection?
Yes. An exchange seal helps you avoid downtime. We collect removed seals by courier, examine them with a short damage report and return them; after repair or fitting we test the seal, on request with a test report.
Are these original parts?
No. They are compatible spare parts that fit these homogenisers. SEEFRIED is not affiliated with the machine manufacturers.
Should the shaft also be replaced when changing the seal?
We recommend it. With age, the shaft can become unbalanced, and it wears in the area of the mechanical seal. In both cases, a new seal on the old shaft would have a much shorter service life.
What happens after a crash in the homogeniser?
If, for example, a foreign body gets between the teeth, rotor and stator can be damaged. Rotor, stator and shaft then have to be replaced. We supply the parts and fit them on request.
Do you also fit the mechanical seal?
Yes. We dismantle the homogeniser, fit the seal and shaft and reassemble it – in our workshop in Weyhe, Germany, or on site at your plant. In our workshop the usual lead time is 2–3 weeks, from 5 working days with advance planning and no major damage.
More about our service: Maintenance & servicing · Repair & troubleshooting · all services
Last updated: October 2026
All trademarks and product names mentioned, in particular Vakumix, NETZSCH, LambdaVita, KappaVita and GammaVita, are the property of their respective owners and are used solely to identify the products offered. This is not an offer from the manufacturer. SEEFRIED Verfahrenstechnik is an independent supplier and is not affiliated with these manufacturers; the mechanical seals offered are compatible spare parts, not original parts.