Diaphragm fabric

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jcfx
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Re: Diaphragm fabric

Post by jcfx » Sat Nov 09, 2019 6:58 pm

Harold, have you looked at McMasters offerings for fabric reinforced rubber materials ?
I took a brief glance thru their Buna-N and Viton rubber sheets and some of them come close to
your .036 thickness ( 9402K22 ) most of what McMaster offers is 1/16" thick.
I'm not sure where this cutoff valve is situated in relation to water temps, but if the valve encounters
hot water, temperature resistance would have to be a factor in your material choice.

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Rich_Carlstedt
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Re: Diaphragm fabric

Post by Rich_Carlstedt » Sat Nov 09, 2019 8:20 pm

Harold, I know you want to keep the sensor cherry, but
you could substitute a air compressor cut off switch or other none water pressure sensor
by adding an air leg ("T") and putting the sensor at the top in the air space where it never contacts water .

Rich

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Bill Shields
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Re: Diaphragm fabric

Post by Bill Shields » Sat Nov 09, 2019 9:11 pm

consider using a water pressure on / off switch as is used for a water well pump.

suggestion for something (or similar)

https://www.mcmaster.com/pump-pressure-switches
Too many things going on to bother listing them.

curtis cutter
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Re: Diaphragm fabric

Post by curtis cutter » Sat Nov 09, 2019 10:21 pm

I have used these Murphy switches gauges on irrigation secondary pumps to shut down motors. If the supply from the river quits, the model 20P-150 shorts a power lead to ground killing the booster motor and saving the booster pump from running dry. The specific part number is 05-70-3121.

I have a functional one that was removed if you want to check it Harold. Is has a 1/8" MPT inlet.

http://shopping.murcal.com/Catalog/20P- ... -Swichgage
Gregg
Just let go of it, it will eventually unplug itself.

Harold_V
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Re: Diaphragm fabric

Post by Harold_V » Sun Nov 10, 2019 3:01 am

jcfx wrote:
Sat Nov 09, 2019 6:58 pm
Harold, have you looked at McMasters offerings for fabric reinforced rubber materials ?
Yeah, that's one of the many sources I've investigated. While they offer multiple thickness materials in a myriad of rubber types, the reinforced material begins @ 1/16" thickness. I've not found anything thinner thus far.
I took a brief glance thru their Buna-N and Viton rubber sheets and some of them come close to
your .036 thickness ( 9402K22 ) most of what McMaster offers is 1/16" thick.
Unfortunately, none of those are nylon reinforced. I would hesitate to gamble on a substance that may rupture. Losing cooling when the furnace is hot isn't an acceptable option.
I'm not sure where this cutoff valve is situated in relation to water temps, but if the valve encounters
hot water, temperature resistance would have to be a factor in your material choice.
The design is quite good. The motor/generator set is built of three units, each of which is mounted side by side. The end that contains all of the controls houses the pressure gauge, and it is fed by the cooling water at the inlet, so it shouldn't see temps beyond ambient, or perhaps slightly higher, depending on how efficient the cooling system operates. I am using a huge radiator to cool the heated water, so it should operate near ambient temperature. Flows only about ten gallons/minute. The unit can be fed water @ 110°F and operate properly, so temp isn't much of a concern. That would be especially true if I can get a piece of proper fabric. These pressure switches have been used by Ajax for a very long time (they were in use in the mid 20' and were still being used in the 60's, when my power supply was built). The only real problem with them is that they have some steel in their construction, which, over time, rusts. I have already made a new stainless cover, which eliminates corrosion 100%. No big deal. After all, I am a machinist. The diaphragm is simple--just a circle with six holes around the perimeter. Using the original switch, altered as I have done, is, by far, the easiest solution, and I strongly suspect that the available diaphragm material will be more than adequate.

I have intentionally chosen to avoid any switches that are not corrosion proof. While that isn't likely to be a serious issue, I don't want to have to back track on any of these things. It is for that reason I have eliminated from consideration any type of replacement. Even switches intended for water application have steel in their makeup, and it is exposed to water. If you guys had any idea of the amount of work I've gone to to clean up the cooling system of this device (a lot of rust was removed), I think you'd better understand my posture in this matter. I simply don't want a repeat of what I know would happen.

Thanks to all for you thoughts and suggestions.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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tornitore45
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Re: Diaphragm fabric

Post by tornitore45 » Sun Nov 10, 2019 11:10 am

Basically you want a piece of a mackintosh raincoat.
If all else fails you can sandwich a Teflon layer between two silicon reinforced fabric layers.

Look at McMaster under "Fabric" AND under "Gasket" is not known if some fabrics are water proof or porous but some may be impermeable.
Mauro Gaetano
in Austin TX

Harold_V
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Re: Diaphragm fabric

Post by Harold_V » Sun Nov 10, 2019 5:20 pm

Yeah, it's the impermeable quality that makes me hesitate to make a choice on materials I have uncovered. McMaster is where I've looked, but the vast majority are NOT reinforced. In my mind, it must be made clear that the material can function as a diaphragm.

I can obtain diaphragm material---it's available on the market, although not easy to find. What I can't find is the same thickness, leading me to think that it has improved over the years, so thinner material serves the purpose adequately.

In this case, it's obvious that the thicker material was used to help seal, but I can overcome that issue by taking a shallow cut on the sealing surface, which is made of stamped steel, 1/16" thick.

I am gifted with two qualities. One is persistence. The other is that I'm unwavering. I will win this war! :-)

H
Wise people talk because they have something to say. Fools talk because they have to say something.

jcfx
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Re: Diaphragm fabric

Post by jcfx » Sun Nov 10, 2019 11:43 pm

McMaster does have sample packs of rubber sheeting, 8450K2, quite spendy for 15 assorted 4x4 or 6x6 sized sheets.
The 9402K22 I mentioned I'll guess is reinforced, since the product description says it's a aramid ( kevlar ) /buna-n blend
it's probably worth it to ask McMaster for a sample of that particular rubber sheeting.

I'll also assume that you tried to look up the manufacturer of that pressure switch ?
if they were swallowed up in acquisitions over the years that particular pressure switch might still be made
but under a different name. I Googled "Ajax pressure switch" and got a link ( in the UK ) for a supplier, not sure if
the switches are even close to what you have.
http://flocare.net/ajax/

Harold_V
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Re: Diaphragm fabric

Post by Harold_V » Mon Nov 11, 2019 2:20 am

jcfx wrote:
Sun Nov 10, 2019 11:43 pm
McMaster does have sample packs of rubber sheeting, 8450K2, quite spendy for 15 assorted 4x4 or 6x6 sized sheets.
Agreed. I'd be far better served to simply use the material that's available, as it is, at least, intended to be used as a diaphragm.
The 9402K22 I mentioned I'll guess is reinforced, since the product description says it's a aramid ( kevlar ) /buna-n blend
it's probably worth it to ask McMaster for a sample of that particular rubber sheeting.
Thanks for that bit of information. I am aware of Kevlar, but was not familiar with the word aramid. Unfortunately, that's likely not a good choice, as the diaphragm must be capable of stretching, and I strongly suspect Kevlar doesn't permit that quality. Sort of the same reason they don't use nylon rope when stretch isn't acceptable. I think they use polypropylene, which resists stretching. They make mention that the 9402K22 material is intended to be used for making gaskets, so that sends up a red flag for me. Gaskets made from that particular product most likely resist blow-out, in part because they don't readily stretch.
I'll also assume that you tried to look up the manufacturer of that pressure switch ?
Indeed I did! And, in fact, I've heard from them, but only via a message that they have forwarded my request to the local rep. That was Friday, so I have yet to hear from them, but I'm not hopeful. I had inquired about a rebuild kit, or, at the least, diaphragm material. The company who made these switches is Penn, and they're readily found online. Unfortunately, their web site shows absolutely nothing similar to these pressure switches, which comes as no surprise to me, considering how long ago they were originally built, and how modern technology has likely replaced them with totally different items. Bear in mind, I am not even remotely interested in trying to adapt something modern, as I strongly suspect that the price alone will make it less attractive to me. The problem I'm facing can be solved very easily without re-designing the wheel, and there's not really any benefit in doing so beyond the simple change I made (eliminating corrosion).
I Googled "Ajax pressure switch" and got a link ( in the UK ) for a supplier, not sure if
the switches are even close to what you have.
http://flocare.net/ajax/
I strongly suspect that the link provided is not even remotely related to the switch makers. Ajax purchased (and slightly modified) the switches they used. I regret not having made mention of that fact, so readers would have a better understanding. Anyway, thanks so much for your dedication to this issue. I'm really impressed with the efforts folks go to to try to help.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

Harold_V
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Re: Diaphragm fabric

Post by Harold_V » Mon Nov 11, 2019 2:44 am

Rich_Carlstedt wrote:
Sat Nov 09, 2019 8:20 pm
Harold, I know you want to keep the sensor cherry, but
you could substitute a air compressor cut off switch or other none water pressure sensor
by adding an air leg ("T") and putting the sensor at the top in the air space where it never contacts water .

Rich
Hey, Rich! It's been a long time since we chatted.

In this case, I'm not really concerned about altering the machine, just want it to be functional, and reliable. Fact is, I have already done some intense changing, due to the failure of several relays that had been subjected to outdoor storage. They were no longer reliable, and were built such that I couldn't access the contacts to clean them without damaging the relays. As a result, I installed new relays, using just the base from the originals so wiring would be simplified. Don't know if you'd be interested, but I posted on that in the old thread, which you can access here: viewtopic.php?f=24&t=105394 There's a picture or two of the installation, along with a description.

As for the idea of using a T, while that has the potential to limit how much water might enter the switch, it wouldn't solve the problem. The original cover was badly rusted, and vapors, if not water, would still be able to reach the diaphragm. I figured it was easily solved by making a new cover from stainless, which I have already done. Now water contact doesn't matter.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

rrnut-2
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Re: Diaphragm fabric

Post by rrnut-2 » Mon Nov 11, 2019 5:57 am

Hi Harold, I know where your coming from on the cooling system. The Inductotherms used Barksdale pressure switches made with all SS, so no rusting. Also, on the temperture switches coming from the furnace or furnaces, they used manual reset Klixon switches. As a mater of fact, they used those everywhere. The manual reset was so you could locate the offending circuit quickly. Just a little information in case you need it.

Jim B

curtis cutter
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Re: Diaphragm fabric

Post by curtis cutter » Mon Nov 11, 2019 10:38 am

I got to wondering about the materials used on fire engine motor governors that use a diaphragm to control engine throttle. I did a search thinking that perhaps there might be material available for them and found this site:

https://www.harkesh.com/rubber-diaphrag ... gI9u_D_BwE
Gregg
Just let go of it, it will eventually unplug itself.

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