A perfect O-ring for perfect coffee

The customers of Angst+Pfister are superbly equipped for the international market with PERTEC® UP VMQ – the compound unites outstanding product performance with all the major approval requirements for the drinking water and food sector on all continents. For Digmesa, manufacturer of precision flow sensors, use of micro-talced PERTEC® O-rings along with custom packing has resulted in significantly lower rejection rates during production.

May I take your order? A coffee, espresso, ristretto, an Americano or perhaps the latte after all? Taste may vary from person to person – but quantity is never a matter for discussion! The precision flow sensors made by the Swiss company Digmesa control the right quantity in the coffee machines of the top coffee outlets. They channel an exact amount of liquid into your favourite caffeine drink. And Angst+Pfister supplies the perfect O-ring to keep the flow sensors tightly sealed. Ten million components annually – this is the figure covering a range of sectors and customers – demonstrate on a daily basis that the innovative, high performance elastomer compounds made by Angst+Pfister handle extremes and keep on going and going and going... 


A unification of numerous properties  

Angst+Pfister developed the PERTEC® product portfolio specifically for such applications: O-rings, mould parts, membranes, currently available in 5 different high performance elastomer compounds for a range of industries and applications. The PERTEC® UP VMQ O-rings for Digmesa not only provide a tight seal for longer, they also uniquely combine the properties of durability and maximum purity, for applications in the food and drink sector, with production and mechanical improvements: “Circularity and evenness are critical for these rings,” explains Reto Müller, sealing technology product leader at Angst+Pfister. In other words, the products have to be perfectly round and lie absolutely flat on a surface. “That’s a real challenge for O-rings with a small cross section diameter and relatively large internal diameter.”

To the customer on air cushions

The rings are built into the flow sensors at Digmesa (see illustration). During the automated assembly process, they must not fall into the multi-part housing – which is why absolute circularity is required along with prevention of distortion. And when the housing is being connected, the rings have not to stick, even under the minimal force applied – hence the importance of the friction value of the seal. Packed and stacked in boxes in their thousands – the weight of the rings alone make maintaining circularity, smoothness and the surface characteristics difficult after delivery to the customer. “We consequently designed a special bag with air cushions for transportation,” remarks Yves Riedo, sealing technology senior engineer at Angst+Pfister. In this way deformations are avoided, the rings stay round and their surface is kept smooth.

One by one

Once at Digmesa, the O-rings are taken from their bag and enter the fully automated assembly via a chute. “The chute gives the rings a thorough shake to move them on,” says Yves Riedo. But this carries the risk of the rings sticking to one another rather than advancing to their intended destination in the flow sensors. “We solved this problem with a special surface treatment,” relates the product manager Enrico Donati. The micro-talcing treatment functions like baby powder and keeps the PERTEC® O-rings separated by reducing the adhesion typical for silicones. “As a result, Angst+Pfister has significantly reduced our rejection rate,” Michael Perret, production leader at Digmesa, is pleased to report. “We used to treat the surfaces ourselves, now we can rely on the competence of Angst+Pfister.” When the rings are not perfectly circular and smooth, or they clump together during assembly, then the machines stop – and have to be restarted manually. That costs time and money.

Many markets – one product

Angst+Pfister’s PERTEC® O-rings have one more advantage: They comply with all the industry-specific approval requirements of the major markets, whether it is approval for the European, Chinese, South American or US markets. “This is an emerging trend,” Reto Müller acknowledges. In the past compliance with the requirements of the US markets was generally sufficient for the international companies. Nowadays, more businesses than ever before are attempting to comply with the specific health requirements of all the markets. Angst+Pfister’s PERTEC® products meet those requirements. So now, how about a perfect cappuccino? 

Flow meter with PERTEC® O-ring

The PERTEC® Angst+Pfister O-rings meet all
industry-specific approvals for the major markets.

Digmesa Yves_Riedo_APCH (2).jpg

«We consequently designed a special bag with air cushions for transportation.»

Yves Riedo, Senior Engineer Sealing Technology, Angst+Pfister Group

More information about performance compound approvals


PERTEC® UP VMQ complies with almost all food contact,
pharma and medical regulations worldwide.

3-A Sanitary Standard Number 18-03 Class I
ADI free
BfR XV (Silicone)
D.M. 21/03/1973
DPR 777/82
DVGW EN 549 D2/H3
DVGW W 270
EC 1935/2004 article 3
FDA - CFR 21 - 177.2600 food a) - f)
French Arrete 17.12.92 No. 293 (migration test)
GB 4806.1-2016
GB 9685-2016
GB 4806.11-2016
GMC/RES. N° 28/99
KIWA NSF/ANSI 51 formulation
KTW Guideline cold water (23 °C) and hot water (85 °C)
LFGB § 30/31
PAH Category 1 (AfPS GS 2014:01)
PAHs requirements according Regulation (EU) No 1272/2013
Phthalate free
SR 817.023.21
USP Class VI Chapter 87 and Chapter 88, 121°C

Moreover due to the high purity of the material also many other regulations can be fulfilled like for example NSF 61 for drinking water or WRAS (BS 6920).

More information about Angst+Pfister in the Process Industry