Peppersass wrote:I don't know if it's really 20 BAR, but I do know that there's no bypass valve in the gear pump. If there's no expansion or OPV valve between the gear pump and the needle valve the pressure will soar. However, Slayer uses the FG model of the gear pump, the motor of which has a current-limiting circuit that maxes out at about 85W. I'm believe this means the pump can't exceed its design limit, which is 20 BAR. The fittings downstream, OTOH, are another story.

Dick - we did the analysis for your GS/3. I have to be careful of over pressure - you and Slayer don't. Unlikely they are getting anywhere over 12-14bar. And you measured it maxing out.

Edit: To correct my post the following is probably wrong. It seems the pressure is not from the pump but from the expanding water in the brew boiler. The setting on the expansion valve was 15bar and therefore the pressure was higher than possibly designed for (albeit 20-30% over 12 bar is a rather thin margin).

The following is probably wrong but kept for thread integrity:
To me it looks like:
1. The Viton seals are of really poor quality; they look baked, and Viton should never look baked. Both seals come from the same batch - both are bad. They may even be some "Fake Viton" elevated temp NBR painted green in China... (with Slayers reputation I hope they were duped rather than complicit)
3. You run the pressure a tad high and long PI - or do more shots. So your "Fake Viton" seals break before other peoples' do....

http://www.youtube.com/watch?v=2qGwMb2c6y0
Of course, I also thought about the reason why the new seal was leaking at the next use.
I have to go further.
I came home in the afternoon and wanted to test the new red speed SSP burrs from Frank.
So I started the Slayer first. After 20 min it was at temperature. After grinding the first shot, I screwed in, paddle laid, it made clack but there was no water. I could not explain. What I did not know at the time; my wife shut off the water line at the corner valve in the morning.
After several attempts, I turned off the water at the corner valve, but without knowing it, I open it. I removed the upper front plate of the Slayer and removed the magnetic switch from the valve. Then I saw that the green gasket had been swollen from the missing screw to the bore of the flange. I then unscrewed the flange, then the water exited, which can be seen on the video - the seal is probably broken at this time.
During the first leakage of this valve, the opposite side was affected, and the flange had lifted there. The flange is made of stainless steel. It was probably a bit bent.
After I have put a new hole with a screw there, the opposite side probably lifted a bit and therefore it was so quickly leaking there.
Nevertheless, it can be said that the Parker solenoid valves do not withstand a line pressure of 50 psi with two screws. The factory indication of Slayer that the machines work up to 70 psi is inaccurate.
The mounting of the parker ventile with only 2 screws is grossly negligent and not to apologize.
The partly loose screw connections of the pressure switches and copper lines also not.
The processing of my Slayer is simply absolutely inferior.
The processing is in no way comparable with a La Marzocco Strada EP, in Germany by the same prize.
greetings
Jürgen

Why are you saying 50PSI? That valve is after the pump and should be seeing almost 200PSI (at least as far as I understand it......).

If I understood your last post, the PSI push the seals outward and that slowly pries and lifts and (eventually) causes the flange to bend? If you are right the seal would in fact, work as a lever and the force applied may be pretty high. That would be a very unfortunate.... Definitely recall territory (or sending a replacement valve assembly and spare screws).

How old are those torn Orings?

Frank,

I would definitely be checking the Expansion Valve Setting. I agree with you that 2 screws is not at all best practice, but there must be hundreds, if not thousands of v3 Solenoid Valves running in commercial environments all over the world.

The expansion valves are not great. The perish all the time. We have our own replacement Viton seals for the Expansion valves and they hold up way longer.

Cheers,

Sean

Why are you saying 50PSI? That valve is after the pump and should be seeing almost 200PSI (at least as far as I understand it......).

You're right, the valves are after the pump, up to 200 PSI water pressure is possible.
The slayer is from 04/2017, about 100 hours of operation. Das last gesket was only one hour old.
Greetings
Juergen

Jurgen,

You are correct - that valve will see far more that 50psi, but NO MORE THAN 175psi

There is an expansion valve to prevent more than 175psi

For 2 valves to fail like this in quick succession - the expansion valve simply must be faulty or incorrectly set.

Whilst I may not agree with Slayer using only 2 Screws (I wouldn't do it that way), they have hundreds, if not thousands of valves operating fine in the field. I have dozens of clients with v3 Slayers operating in huge volume accounts and none have experienced this issue. For you to have 2 in the one machine - something else is awry.

Fake Viton from China or painted green NBR is total rubbish. Slayer DO NOT source those o-rings. They are supplied on the valve brand new from Parker.

They have NOT broken "on the screw"!!! -in BOTH cases, they have 'burst out' of the weakest point - the closest point to the edge of the plate. One side is still secured. Viton is not overly elastic. It is simply going to snap at some point and that is exactly what has happened.

I would love to know the number of v3 Commercial Slayers out there, the total number of group heads X 2 (2 per Head) + all the Single group machines and this is the first time that we are hearing this?

No. Sorry, but I call bollocks. Check your expansion valve. The tank should not exceed 12 bar (174psi)

Cheers,

Sean

If there's 20 BAR in the system I agree that the expansion valve isn't set right. But it's not necessarily that it's cranked down too tight. If it's too loose, you have to set the motor speed a lot higher to get a 9 BAR shot. Then when you run the pump against the needle valve you might be generating enough pressure to break the seal.

I have a friend with a Slayer who has the expansion valve set according to factory instructions. His motor speed is typically about 26% to produce an 8-9 BAR shot. That speed is safe with the needle valve set to produce typical Slayer preinfusion times and also provides a free flow rate of about 600ml/min.

I've never seen someone mention the gear pump speed/pressure interaction, so forgive me Dick for asking a follow up.

I've seen a few Slayers that prebrew with a slow brew pressure rise; per the pressure gauge, they rise until about ~3 bar until slow drips. Engaging to full brew jumps the pressure up, and the basket seems to coalesce quickly
Into a central stream.

On my machine, the pressure builds and builds through prebrew, that even in prebrew phase, the pressure gauge reads up to 9 bar. It's almost as if it takes until that point for the basket to saturate. Engaging to full brew barely changes the stream/basket saturation.

Running 19% pump pressure, SHURflo demand pump water supply. Any thoughts?

Zanderfly wrote:Any thoughts?

Yeah, I think your machine is behaving exactly as I would expect a Slayer to act.

The needle valve simply slows the rate at which the basket fills. Once the basket is full, pressure builds until max pressure is reached. Since the pump is running throughout the sequence, max pressure is nominally 9 BAR. Once max pressure is reached, the pressure is 9 BAR throughout the system, regardless of the size of the needle valve opening (i.e., pressure is equalized.)

Well, it's not exactly 9 BAR-- there's a small pressure drop across the needle valve due to the fact that there's some flow through the puck, but you can't see that pressure drop because the pressure gauge is on the output side of the needle valve. However, as the shot progresses and the puck becomes more permeable, you can see the pressure decrease.

When full brew is engaged, the pressure is already very close to the max, so you only see a small jump in pressure that's due to the aforementioned pressure drop (likely 1 BAR or less.)

Note that the rate at which pressure builds depends on the pump speed and the size of the needle valve opening. Max pressure is determined by pump speed and puck permeability.

I don't know what's going on with the few Slayers you've seen that have a large jump. Are these the same model as your Slayer? I'm not familiar with all their models, but what you describe sounds more like what happens with line-pressure preinfusion -- as opposed to using a needle valve. In that case, the pump is turned off during pre-infusion. Line pressure controls the preinfusion rate. When the basket fills, the max pressure is only 3 BAR because that's the line pressure. When the pump is activated, pressure quickly ramps to 9 BAR -- much faster than a normal shot because the basket is already full and partly pressurized. Perhaps these Slayers are older models that don't have a needle valve?