Barksdale 0.05bar pressurestat 1st look - Page 5

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Java Man

#41: Post by Java Man »



Here it is.

Rick
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JonR10

#42: Post by JonR10 »

Java Man wrote:Here it is.
Yipes! That's a crispy critter indeed!

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another_jim
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#43: Post by another_jim »

Java Man wrote:
I took the failed MATER apart, and it's obvious that in my machine, it's the electrical contacts that cause the short lifespan. I leave my machine on 7/24. I'm sure others may have scaling problems, too, and possibly diaphragm failures, but in ~ 18 months of use, the contacts in mine are burnt to a crisp.
The Mater and Ceme are 10 amp, submarginal for US 110V use. Chris Nachtrieb got so sick of SSR heat death when they are installed inside machines without good heatsinking, that he's gone to the Yaeger Pstat and direct heater switching for the Quickmills. The Yaeger does 15 amps and may prove reliable. I don't think its deadband is any better than the other standard pstats, but it has the small form factor of the Mater and Ceme.
Jim Schulman

Java Man

#44: Post by Java Man »

Here's a potential reason why converting the WEGA pressurestat to a PID replacement may be unnecessary overkill. I would appreciate any thoughts anyone cares to offer.

There are no unused boiler plugs/ports on the Wega, and the port used by the pressurestat has a potential problem as a thermocouple port. It doesn't go straight into the boiler -- it shares a boiler port with the steam valve line, and screws into a "T" off the steam valve line. This suggests it may not have the temperature stability of a thermocouple going straight into the boiler, so the superior temperature stability and low deadband properties of a PID control may be wasted. (It's possible these properties would be wasted on an E61 machine anyway, since fairly good brew temperature control can be achieved by a variable flush using Eric S's brew water temperature monitoring kit.)

Any thoughts on whether a compromise location for the thermocouple makes pressurestat replacement with a PID a less desirable conversion -- reaping improved reliability, but potentially not helping at all with boiler temperature stability?

If so, it may be worthwhile to simply install a more robust pressurestat like the Sirai, and make a habit of replacing the diaphragm at regular intervals. In my case, the MATER that failed after 18 months did so because of its undersized contacts. The diaphragm, on the other hand, moves freely and the pressurestat body shows only a very light scale deposit. Fitting a Sirai and replacing the diaphragm every year or two would probably keep the Sirai operating very reliably.

Thoughts?

Cheers,

Rick
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another_jim
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#45: Post by another_jim »

I don't think it would present a great problem to seal a bare TC against 1.5 bar -- the one I tried with simple silicone glue held till 5 bar (alas on a 9 bar line). Get a cap that fits the size of the port, drill a hole in it and snake the TC through. Then seal it with a real sealant, as opposed to silicone glue, like viton glue sealant (e.g. McMaster 77495A15).
Jim Schulman

Ken Fox

#46: Post by Ken Fox »

Java Man wrote:Here's a potential reason why converting the WEGA pressurestat to a PID replacement may be unnecessary overkill. I would appreciate any thoughts anyone cares to offer.

There are no unused boiler plugs/ports on the Wega, and the port used by the pressurestat has a potential problem as a thermocouple port. It doesn't go straight into the boiler -- it shares a boiler port with the steam valve line, and screws into a "T" off the steam valve line. This suggests it may not have the temperature stability of a thermocouple going straight into the boiler, so the superior temperature stability and low deadband properties of a PID control may be wasted. (It's possible these properties would be wasted on an E61 machine anyway, since fairly good brew temperature control can be achieved by a variable flush using Eric S's brew water temperature monitoring kit.)

Any thoughts on whether a compromise location for the thermocouple makes pressurestat replacement with a PID a less desirable conversion -- reaping improved reliability, but potentially not helping at all with boiler temperature stability?

If so, it may be worthwhile to simply install a more robust pressurestat like the Sirai, and make a habit of replacing the diaphragm at regular intervals. In my case, the MATER that failed after 18 months did so because of its undersized contacts. The diaphragm, on the other hand, moves freely and the pressurestat body shows only a very light scale deposit. Fitting a Sirai and replacing the diaphragm every year or two would probably keep the Sirai operating very reliably.

Thoughts?

Cheers,

Rick
I'm not familiar with the design of the Wega boiler; are you sure there are no other potential ports?

From the standpoint of the probe, you might be able to get a flexible encapsulated one, or one that has a bend in it that could be snaked through the T, but I'm not sure how practical that is. If you do use a bare TC as Jim suggests, you'd want to be sure not to use one that might rust, e.g. a type "J."

Although I think that Jim's solution is workable, all things considered I'd probably go the pstat route unless there is some way to find a port where an encapsulated probe can be put in and where you can get a standard fitting to close it.

ken
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cannonfodder
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#47: Post by cannonfodder »

I drilled and tapped the boiler plate on my lever machine. Mounted a 1/8 inch compression fitting and used a type K probe. In the final mount, I put a brass washer with a rubber washer between it and the boiler plate for an extra measure of seal.


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Java Man

#48: Post by Java Man »

Ken Fox wrote:I'm not familiar with the design of the Wega boiler; are you sure there are no other potential ports?
Yes, unfortunately.
Ken Fox wrote:From the standpoint of the probe, you might be able to get a flexible encapsulated one, or one that has a bend in it that could be snaked through the T, but I'm not sure how practical that is. If you do use a bare TC as Jim suggests, you'd want to be sure not to use one that might rust, e.g. a type "J."

Although I think that Jim's solution is workable, all things considered I'd probably go the pstat route unless there is some way to find a port where an encapsulated probe can be put in and where you can get a standard fitting to close it.

ken
Unfortunately, it seems there is no problem-free solution to boiler pressure control. As I see it, boiler pressure control devices have three requirements -- 1) form factor/size; 2) the consistency of boiler pressure (i.e. low deadband and repeatable high/low pressure); and 3) durability.

The MA-TER and CEME are both very compact, and operate with good consistency when new. I don't know about the durability of the MA-TER diaphragm, but it's unlikely many have had the diaphragm fail because the switch is ridiculously undersized for full-current switching in a 110V machine and fails or scales up long before the diaphragm fails. The CEME reportedly has a durable metal diaphragm but also suffers from undersized electrical contacts.

The Barksdale has comparable form factor to the CEME and MA-TER, and a very low deadband, but durability is not established. It was not designed for espresso machine service -- its temperature range tops out at less than 170F according to its specs.

The Jaeger Chris Coffee is selling has similar form factor to the CEME and MA-TER. I haven't seen the electrical specs, but it is a relatively compact unit, and I wouldn't expect its electrical contacts to be as robust or durable for full-current switching as those in the Sirai.

The durability of any of the pressurestats that typically fail due to burnt contacts would likely be improved by insulating the boiler to decrease heater cycling frequency.

The Sirai installed in many commercial machines has 3 large sets of electrical contacts, undoubtedly a factor in its reputation for robust electrical durability. It has a perishable diaphragm, which may be its Achilles heel in hard water environments. The diaphragm is replaceable, but the Sirai is large and difficult to fit into some semi-commercial machines.

A PID replacement for a pressurestat offers a longer expected life and near-zero deadband, but has form factor problems since it requires an external project box. It is more expensive than the others and requires some machine modifications. It's possible that its deadband advantages over conventional pressurestats are irrelevant in an E61.

All of this leads me to conclude that for operating my WEGA in my very soft water environment, fitting a Sirai to my machine is the best compromise.

Thanks to all for your suggestions and comments.

Cheers,

Rick
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JonR10

#49: Post by JonR10 »

I'm resurrecting this thread because the Barksdale p-stat failed on Wednesday night.
Luckily I just got a Gaggia Espresso to play with so I pulled shots using it for a few days while I fitted the Sirai into the WEGA.

I'll come back and post some pics showing the devices side-by-side for reference later.

Right now I'm starting to wonder if my machine's pressure gauge is messed up.....
Remember when I observed that the factory setting on the Barksdale was 0.5 bar and I had to crank it all the way down to get over 1 bar?

Well the factory setting on the Sirai also seems to make my boiler pressure read 0.5 bar and I have to crank it as far as it goes to get over 1 bar on the high side. Now it seems to be running 0.85-1.05 bar. I'm not very pleased to say the least. The Sirai is supposed to be rated up to 1.4 bar.

Anyway, I suppose it's possible that my WEGA's pressure gauge is off (although this seems unlikely). I have emailed TerryZ and Brian and Devon and EPNW so we'll see what they say. In the meantime, there's nothing wrong with the shots I'm pulling (on the Gaggia as well as on the WEGA).

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JonR10

#50: Post by JonR10 »

JonR10 wrote:Right now I'm starting to wonder if my machine's pressure gauge is messed up.....
Remember when I observed that the factory setting on the Barksdale was 0.5 bar and I had to crank it all the way down to get over 1 bar?

Well the factory setting on the Sirai also seems to make my boiler pressure read 0.5 bar and I have to crank it as far as it goes to get over 1 bar on the high side. Now it seems to be running 0.85-1.05 bar. I'm not very pleased to say the least. The Sirai is supposed to be rated up to 1.4 bar.
OK, tonight I have confirmed that the WEGA pressure gauge has been off by quite a bit. And so I now apologize for my comments about the Barksdale p-stat. Apparently I was pushing that device to its limit and beyond without even knowing.

Also, the Sirai is indeed rock-solid as advertised. It took a couple of days of abuse and didn't let me adjust it beyond its capacity. It's now happily clicking away running at proper boiler pressures (I'm at roughly 1.0 bar - 1.3 bar). No wonder I pull such long cooling flushes, eh?




Well, enough of that. Here are the pics I promised.




Here is the Rube Goldberg setup to attach the Barksdale to the WEGA. Notice the hi-tech insulation job?
Image









And for comparison, here is the side-by-side of Barksdale with Sirai. A slight difference in scale :wink:
Image






And here is a good shot of the Sirai Contacts, all three sets.
Image





And here is the install job in progress.
I had to do some creative p-stat tube bending and I had to make a couple of jumpers and a grounding wire, but it came out pretty nice.
Actually, it kinda looks like it belongs there.....
Image