Cobbs Relief Valve.

T

The Magician

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Any one using Cobbs 2" brass relief valve. How does it work and compare to other vac. relief sys?
 

FastEddie

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It works OK but the rubber O-ring was problematic on mine. I took it apart and I'm yet to find a bearing though. It's featured as bearing shaft supported. I don't think so. I used it as a temp replacement while my Kunkle was apart for a cleaning.
 

FastEddie

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That Bayco is one smooth beast Greenie! It seldom opens but when it does its just below 16"
 

Larry Cobb

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Eddie;

The shaft on our 2" brass valve is centered and supported by a Delrin (r) bearing.

We also sell Kunkle valves, which have sliding metal-to-metal contact.

The O'Ring on our valve is there to ensure a complete air seal.

If it is not performing to spec, then give me a call.

Larry Cobb
Mikey Board Supporting Member
 

FastEddie

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Larry;

No dis-respect, but I just can't imagine this white nylon sleeve being called a (Delrin) bearing.

Perhaps you guys sent me the wrong model? I called and explained the problem and they told me there definitely is a bearing inside and I could not return it because I used it. The main reason I ordered it was because I had my Kunkle apart and I wanted to try your bearing shaft supported valve to see it's performance.

CIMG2263.jpg
 

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tman7

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How well does it work? Does it begin leaking well before the set point like other spring reliefs? Can it be mounted on the waste tank?
 
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Shawn Forsythe
Larry can vehemently disagree with me, if he wants, but the truth should be known. Here goes.

Be it known that Larry has long been an ardent detractor of Kunkles, but now he sells them.

That brass valve of his is just an ordinary re-worked check valve with a delrin bushing. Nothing new at all. TM manufacturers from the early 70's were doing that before they got around to making their own more specialized valves, albiet not many of them were any better, and some were even worse than the re-worked brass foot/check valves.

Now, the plastic bushing does permit the valve to work more smoothly, which is good in a small way, but then for how long too. Delrin is inexpensive, but is mediocre too. But it does NOTHING to stem the fundemental flaw of a traditional spring loaded vac relief valve. That is the valve begins to open long before the full relief setting. This is due to the fact that coil springs deflect a a little under small loads, and deflect more under additional loading. Now, maybe that o-ring on "larry's" valve may just serve a "hillbilly purpose", inasmuch as it may cause the valve to stick closed a bit longer, but it is a monumentally "hokey" way to serve that purpose. In fact, it is a general operating principal that you should NOT have a soft seat on any safety relief valve. That is because soft seats can stick and cause unpredictable and unrepeatable cracking tensions.

A air-vacuum relief valve should have a precision metal/metal seat so that the opening tension stays stable.

Precison vacuum relief valves, like the Kunkle and the Bayco are nothing new either. They have been used for many years on ultra similar applications such as own. Oil & sewage reclamation pump trucks have been using them for years to protect the blower and vacuum systems from vacuum overload. They are seeing more prominent application in our industry because of real competition and desire of end users to maximize potential CFM from existing systems. TM manufacturers are also waking up to this demand. Masterblend's units are equipped standard, and a few others are ready for introduction this year.

Ordinary precision spring valves are nothing new either. Oilite bronze sintered bushings with oil impregnation for friction have been implemented, as well as precision stainless steel sealing surfaces for near "bubbletight"(air leak proof) design have been used by a couple of Manufacturers. However, ALL of them still used an ordinary coil spring that creeped open, and thus lose CFM almost at the slightest load.

You want a true test of a relief valve? Blow some smoke into the relief valve inlet at 2" hg below the advertised setpoint. If that smoke is drawn in with any but the slightest velocity, you have a very significant loss. But of equal importance is that the very same valve relieve the entire flow capability of that same unit,at the set point, not to exceed the redline vac level of the blower. In a properly designed system, that valve is NOt there to regulate vac levels, but to offer a safety mechanism for excess vac levels.

If you find that with your hose/wand setup that the valve is oscillating, then it simply means that the Carpet/Wand interface is permitting less flow than the vacuum blower is generating. Adjusting the system entails introducing a puposeful flow leak at, or near the wand to permit just enough volume to keep the valve from cycling. This will also benefit extraction, as the velocity in the vacuum hoses will increase, thus adding motive force to the extracted media. (this is NOT the principle described in an earlier thread discussing "free-flow", which IMHO is bunk). Another, but less effective alternative to this is to cap the relief valve with a flow retardation mechanism(drilled holes) that matches the flow of the wand plus the relief opening so that upon restriction opening, the overall flow is such that an equalibrium is established that creates a lift setting just below that of popoff (13-14" hg).
 

Larry Cobb

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Shawn;

We installed our first Kunkle valve on a TM over 5 years ago.

Simply put, the Kunkle IS a spring-loaded relief valve.

It is not a valve I would suggest as an option on our TM.

It cycles to lower vac levels when it opens, unless you modify it with a silly cap with X holes in it.

I am always looking for TM vac improvements, but the Kunkle valve @ 4.5 times the cost of our current vac relief is not a good value for our customer.

Larry Cobb
Mikey Board Supporting Member
 
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Larry Cobb said:
Shawn;

Simply put, the Kunkle IS a spring-loaded relief valve.

It cycles to lower vac levels when it opens, unless you modify it with a silly cap with X holes in it.

Larry,
I wish you would not cloud issues just to focus sales on your preferential product offerings.

First, the Kunkle/Bayco differ monumentally from what I term a "traditional spring vac relief valve" in that the valves do not permit the slightest of significant flow until the valve mechanism has moved to the point where it is calculated/set to relieve. This is very different from all the other valves which use a flat poppet, where their exists relieving flow at lift figures far below the full relief point. Just as in a "traditional spring vac relief valve", the kunkle spring does move, but the cylindrical/long piston type of valve does not reveal any opening flow until the set point is reached.

Second, your "silly cap" reference is the "less effective" alternative I describe for reducing cycling. The primary method I point out leaves you will little ammunition, so I guess that's why you don't mention it. However, and a big "however", is that even the "silly cap" means greater working vacuum than ANY, yes I said ANY, traditional spring valve set at a safe level for the blower. (setting a spring valve at 17-19" hg is an insane way to eek out more performance in that it completely obviates the concept of the principle purpose of a safety relief valve to act as a mechanism to keep load on the system from reaching undesired levels.


BTW, the Kunkle/Bayco is a tad bit more expensive. However the difference is minor, and more importantly the return on investment for the end user is by far a much greater margin. And I've been saying this for years before I was ever in a position with a company that sold them.


p.s., you would be much better off just marketing your valve as an inexpensive alternative to a stock valve, especially when the stock valve is rather mediocre and more expensive. Leave it at that. Sorry, I have a pet peeve when the ordinary is hyped or oversold. Especially when it conflicts with a well researched superior alternative. I've spent way too much time in this to see flippant sales discussions accepted as some sort of revelation. Foe 20+ years I built one of the best spring "traditional spring-loaded valves, with a stainless steel precision poppet, and a far superior bronze oilite bushing, but I still see the kunkle as fundemetally superior after arduous comparison.
 
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Let me state that my posts on this thread are politically incorrect to a rather extreme. Some might feel that people that could be categorized as competitors should try to retain a friendly composure to avoid what is commonly referred to as "flaming". Such can lead to petty sniping on future threads in an effort for the lesser secure of the two "combatants" to further engage simply for reasons of retaliation, outside the original thread.

I hope that in this one instance, at least, my effort is recognized as nothing more than passion for what I truly believe.

Years ago, when encasulation technology was new, the purveyors of the encap products would tout their products as fully and completely competative with all other methods, even residential HWE. I would fight tooth and and nail on these boards, the overhypeing for market penetration, of the new science. Nothing personal was ever involved. I hope that always remains the case, but others may not see it.

I hope that extreme disagreement can remain civil.

Respectfully,
 

Larry Cobb

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Shawn;

I just guess we'll have to disagree on the performance of the "revered Kunkle" valve.

While the factory-set Kunkle did not allow airflow leaks up to the 15" vac it was speced at, once it cycled, it only operated @ 13" of vac lift.

This level is less than our "inexpensive" valve also set @ 15" would maintain.

And, why is it that the $230 Kunkle requires an:

"alternative I describe for reducing cycling"

A very expensive relief valve should NOT require remedies to correct poor performance !!

Larry Cobb
Mikey Board Supporting Member
 
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It's not a remedy, Larry, any more than a delrin bushing is a remedy, or a vac relief valve is and of itself, a "remedy". It's called a system of implementation for maximum performance.

You want to bring up expensive? LOL

Was it not you who said that Crispin valves were a "better design"? LOL
~$1300.00


What a Kunkle/Bayco gives is the absolute maximum "bang for the buck", and if you want to factor labor and dry times, is the least expensive vac relief valve system available. Payback(ROI) is measured in hours, not even days on this one.
 
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Nick,

What? A little too "newfangled" for you? (pronounced with an acute southern drawl) :)

I am worried about you. Your "Cooters Garage" archetype model for system design theory, is getting a tad too serious. But hey, if that's your niche.....LOL
 
G

Guest

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Shawn, Cooters Garage. Hey I like that. You know shawn it is just so amazing how a HACK like myself comes up with something that just out performs kunkle or bayco. With this new system we use I like to think of it in how should one say. The Kunkle being a BB gun and the free flow a tank. using a kunkle is like tanking a BB gun to a tank battle. I have been around a long time not as much as you or larry but more than some self proclaimed gurus who steel ideas from people. Shawn my market love our machine they get a suped up hemi type machine for less than a ford escort with dealer prices.

Next time you are in TEXAS come by COOTERS , home of the


FREE FLOW FREE FLOW FREE FLOW FREE FLOW FREE FLOW
 

truckmount girl

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The first Kunkle valves used in our industry (to my knowledge) was 25 years ago...On Steamway's unit. You can still occasionally find these old workhorses. Currently Masterblend is using them on their hot little El Diablo unit.

The only problem we've ever encountered with these valves had to do with these two issues:

1. These valves (over 100 years old) were not designed for our industry. They were installed for dry material handling. Specifically loading and unloading grain and other dry products from trucks and trains. There is little need for extreme attention to lift tolerances with this application.
The Kunkle Company has an "acceptable tolerance" of plus or minus 4" of mercury. Totally unacceptable in our industry. We found that a new valve often had to be adjusted on the machine to the correct settings for open and closing. The adjustment is simple, but does require breaking the factory seal, and knowing what you are doing. A properly adjusted Kunkle will then perform flawlessly.

2. Because these valves were designed for dry environments, the moisture in our application can cause rust to build up on the cast iron parts, eventually causing the valve to stick. If you use a Kunkle it is important to lubricate it often to avoid this stickiness. Kunkle company recommends NOT lubing the valve, but again, they are basing this on a dry environment.

Frustrated by the wide tolerance in lift setting, we sought out alternative valves and found Bayco valves. They are an aluminum and Stainless version of the Kunkle (which is cast iron and brass), and are slightly less expensive than Kunkles, are set to tighter specifications from the factory and avoid the rust issues. They are also lighter. Unfortunately they do not come in the 2.5" size which is good for fast spinning 47's and 56's. They are only available in 2" and 3" sizes. Requiring many owners of these fast 47's and 56's to do some cutting and arranging to make the 3" installation work.

On our site, 2" Baycos's run $219, 2" Kunkles run $229, 2.5" Kunkles are $399 and 3" Baycos are $499. So the price goes up a lot as you go bigger. We have also found that they make the most difference on smaller machines and/or long hose runs.

We have searched all alternatives and have never found anything to rival a well adjusted Kunkle/Bayco for performance increase.

If someone would like to do a little testing at Mikefest, Summerfest or Connections...we can have someone bring in a properly operationg 33 or 36 blowered unit, with stock spring relief installed, then install alternately, free flow, Cobb, and Bayco valves on the units and test CFM and lift at 50', 100', 200' and 400' of hose out. Wand on and off the carpet. We just need a nearby willing subject truckmount and a high quality cfm gauge.

My guess is that even if we all assembled together and conducted the tests, later there would be accusations of rigging or falsifying results. Why? Because men are involved and something about having a penis makes it very difficult for any of them to admit they were wrong...men and their egos can be very fragile.

:cry:

You all sound like a bunch of 13 year olds on the playground postulating and chest pounding about how your big brother will beat up the other guy's big brother.

Let's all get together and really learn something valuable, and based in fact, not theory or subjective testimonials.

Take care,
Lisa
 
G

Guest

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Lisa , I am currently building a couple of EZ 1636. Why don't you and jeff see about flying into dallas . I bet we could get larry to help us test bayco,kunkle,free flow,and other Items. We could use a the Dyna chem TMS and EZ tms. I also have a powermatic and a 4.0 spitfire I could bring.

I am down with it if you guys are.
 

floorguy

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Doug
shoot to bad we didnt have this discussion a few mths ago...i woulda drove my stuff up there and done a little testing...

as you know lisa in all my talkings with greenie, i think i have "tricked/peaked" my performance out well, and have it running "properly" i think...

shoot foot the gas bill and ill drive anywhere hahahah
 

truckmount girl

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Duane, more than just what works...I've no doubt they all work, but what works best in various applications, most likely what we'd find is that one may work better than another on longer or shorter runs or on certain types of carpets (there is a big difference between CGD, apartment grade, wool rugs, sculptured berber, etc.).

Nick, I'd love to head to Dallas for a few days to do something like this, but right now our finishing and packaging girl is on vacation (In TX!) visiting the grandkids until June, so we are kind of slammed and it's hard to get away for something that's not one of those events. BUT we might be able to swing a 3-day weekend or something.

While playing with this stuff we should also play with air vs water-cooled engines and CDS/PTO's. My guess is there would be a lot of variance there as well. Anyone in the Dallas are with a healthy running Butler?

I'm sure between Nick's shop and Cobb's we could find a shop with the tools required. The hardest part is finding a CFM gauge that works for our application. We would want to be able to test CFM at the wand, ideally placing the meter between the hose and wand. So far I have not found a proper CFM gauge to get an accurate read for this application. Any of you know of one?

....and if we did this, could you all leave your penis' at home? Or maybe send the wives instead? Damn competitive men.

Take care,
Lisa
 

truckmount girl

1800greenglides
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Also, we can't do all of this CFM testing without lift testing as well.

I'm no engineer, but I maintain that lift is dynamic throughout the system and should not be measured at only the blower. In fact, it seems to me that lift and CFM readings are moot EXCEPT at the wand/carpet interface, because that is the only place it matters. The problem being there seems to be no accurate way to measure those figures at that crucial point. If we could find a way to test these forces just inside the lips of the wand, it would be ideal. Even at the wand handle would be better than at the machine.

There are a lot of people here more educated than I....and this industry has a lot of people who came from other industries....so I ask, what is the ideal instrument to get these figures at the crucial points? Also can lift and cfm be dynamic at different areas of the system?

One more question, is the ratio of lift and cfm constant or can it be changed with restrictions? In other words if CFM is raised or dropped by 100, how much will that change the lift reading? If I then raise or lower the CFM by 200 or 500, will that lift ratio stay constant or will it be dynamic?

These are the kind of discussions Greenie and I have over morning coffee...sad huh?

Take care,
Lisa
 

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