Butterfly valve seats--Silicone vs EPDM

[TGTimm]

I started numbering our BVs a year ago so I could keep track of valve seat performance.

Today, I got the first two numbered valves back for seat replacements since I started (out of 29 valves so far numbered). Both had EPDM seats installed Nov. 3, 2015. The seats are now very hard, almost inflexible, and do not seal. The silicone valve seats in the first valves I started tracking are still going strong.

We clean with caustic, ~180F, occasional acid wash (nitro/phos). Apparently EPDM does not thrive in this environment.

Our brewers also prefer the Silicone as it's easier to see any damage to the seats.

YMMV

[gasketman]

Silicone vs EPDM

I'm sure you are looking for feedback from other brewers but let me just add this little information to the discussion. The environment you describe is exactly what EPDM is designed for. However, not all rubber materials are created equal. Let's use an industry analogy and say in the same way that not all Lagers are the same. Some are really good and robust, they use quality ingredients and care in the process. Some use lots of fillers and cheap ways of mass producing it and the quality suffers. Rubber is no different, materials are made from a recipe and the recipe includes not only the ingredients but time, temperature, etc... A good quality EPDM is not an easy material to make. Silicone on the other hand while it still can be made poorly is a much easier material to make and process. A well made silicone material can stand the environment you mentioned too, the biggest drawback is its tendency to tear, and once there is a nick or tear anywhere on the gasket it will soon shred.

Dwight
Brewery Gaskets

[TGTimm]

Thanks, Dwight.

My intention was to present these findings for the enlightenment of others in the choice of valve seat material.

As I wrote, Your Mileage May Vary--these results are from our brewery under our brewing and cleaning regimes.

Most of the silicone and both of the EPDM seats were purchased from Brewery Gaskets, many (including the two failed EPDM seats) within the last year. All of the seats are Tassalini branded.

[Fondeezy]

I just want to echo what gasketman said regarding EPDM versus Silicone.

Silicone has a very low resistance to abrasion and cutting with poor resistance to acids and alkalis. EPDM has a temperature rating of 280F if FDA approved and is very resistant to steam. While EPDM has good resistances to mild acids, alkalis and alcohols, it shines with basic solutions as it can take upwards 5 to 10% caustic.

I would definitely recommend using EPDM over Silicone.

[TGTimm]

I started numbering and keeping track of our BVs in November 2015, so it hasn't been a year yet.

So far, none of the Tassalini branded silicone seats has returned for service. We had some off-brand seats that failed very quickly, leading me to start tracking the valves to determine what lasted the longest.

It is very possible that the two EPDM seats were from the same batch (purchased at the same time) and that batch may have been faulty.

The silicone seats do tend to fail through tearing in the area where the butterfly seats--but it takes over a year for them to do so. The EPDM seats that failed showed no signs of wear--the rubber just hardened and was no longer sealing--leaking from the joint of the valve body.

We inspect every valve every time it goes through the wash, and the brewers prefer the red of the silicone as it's easier to see any damage than with the black EPDM.

Maybe I need to order some more EPDM and keep testing....

[mikeyrb1]

I replaced many of our silicone gaskets with EPDM after a shredded silicone valve in the kettle caused sanitizer to leak into a batch ruining it. I believe the gasket was shredded when a acid clean (using Acid #5 and PBW)was performed on the kettle(I suspected my assistant might have used too much acid #5). Since then, we keep a better eye on the gaskets before and after cleaning. The EPDM has shown much less wear and tear and is generally better, but they do cause the valves to be much stiffer. During breakdown, we disassemble the valves and soak them in caustic. This allows us to get a good look at the gasket whether it is black or red. We don't remove the gasket from the valve though to prevent ruining a perfectly good gasket.

I need that gasket insertion tool on the gasket website, anyone used one yet?

[BrewinLou]

Interesting,
I have had the opposite experience. My EPDMs last much longer. But our CIP is different, I use Birko BruREZ (none caustic) for tank CIP in the 140-150 range. Could be cheap Silicone replacements. The gaskets I replace most often are all on the Kettle valves, the heat is brutal on all types. Always good to hear your thoughts Dwight.

[dick murton]

We've used Viton seals because PAA in particular, even though it is not meant to, chews its way though EPDM faster than Viton

[TGTimm]

All interesting points. I will give the EPDM another try. Possibly I'll try Viton also, as we sanitize with PAA (forgot that part), but it's very dilute.

At every tear-down, we clean the BVs (and all other small parts) in an ultrasonic cleaner, using caustic (don't recall the dilution, something like 1/4 cup powdered NaOH/12 gallons). All valves are visually inspected before as they come out of the ultrasonic and on their way to the sanitizer grant.

[gitchegumee]

Any color you like...

Dwight could confirm this, but I'm quite sure you can get other EPDM colors as well. I'm sure I've seen red ones....

[dick murton]

I've certainly used red and blue seals as well as black, but am not sure of the material. But if suitable, this would be a good way of monitoring a progressive replacement programme. From memory, the different colours varied according to supplier, so it might not be that simple / useful unfortunately.

[gasketman]

Colors

It is possible to make EPDM in just about any color, but it is not generally done. White, black, and shades of grey are most common. Silicone on the other hand is very easy to make in different colors and it has almost no effect on the physical properties of the rubber.

Dwight could confirm this, but I'm quite sure you can get other EPDM colors as well. I'm sure I've seen red ones....

[TGTimm]

While multiple colors might be nice for keeping track of the age of seats, I've started stamping numbers in the outer flange of the valve bodies. This allows me to easily track every single valve in an Excel file. Number stamp sets run around $20. Mine are 10mm tall, which just fits the flange, but a little smaller would take less force to get a good impression.

We don't replace seats on a schedule--for one thing, we haven't enough data to determine when it would be optimal--but when the valve seats shows excess wear or starts leaking. In a few years, I should have enough data to start a reasonable replacement schedule. As it is, after 7 months of tracking, I still haven't seen every valve--I figure at 25 valves numbered, I've replaced <1/5 of our valve seats since I started tracking.

[Ted Briggs]

According to: http://www.hitechseals.com/chemical-...emical_id=1542

Peracetic acid: EDPM, Teflon, satisfactory, Silicone- NOT
Same with phosphoric acid.
Sodium hydroxide: EPDM Satisfactory, Silicone- fair.

Combined with silicone being physically weak, I go with EPDM. For tank manways and tc gaskets too. Teflon occasionally if next to a very hot area or for racking arms where I want it to rotate easier.

[gasketman]

Diluted Chemicals

The thing to know about standard industry literature is that it doesn't take into account diluted chemicals. And going back to my original point, all materials are not created equal. A well made peroxide cured silicone will actually perform quite well under typical circumstances in the brewery. In fact I have customers who swear by my red silicone and use it everywhere even though I recommend EPDM. Teflon would be great for butterfly valve seats, but I have yet to figure out how to make that work...

According to: http://www.hitechseals.com/chemical-...emical_id=1542

Peracetic acid: EDPM, Teflon, satisfactory, Silicone- NOT
Same with phosphoric acid.
Sodium hydroxide: EPDM Satisfactory, Silicone- fair.

Combined with silicone being physically weak, I go with EPDM. For tank manways and tc gaskets too. Teflon occasionally if next to a very hot area or for racking arms where I want it to rotate easier.