Koso Hammel vs CCI vs Copes Vulcan 3

[cian85]

Im doing some research on these particular brands regarding their stacked disk laberynth design to control excesive noise and cavitation mainly in power generation applications and oil industry.
It would be quite helpful if you guys could share experiences (good or bad) when working with these brands and if they actually solved any problems you might have had.

Thanks!

 

[JLSeagull]

I have specified many control valves and only one drag valve. This was a client driven opportunity where an existing installation was breaking pipe supports etc. Very high noise levels above 110 dB can be mechanically destructive. As far as I am aware the drag valve fixed the problem.

 

[JimCasey]

Be very careful.
Noise is one thing. (Expanding compressible gases) Cavitation prevention is something else (liquid flow).
Both use tortuous flow paths but the differences are significant and great. The parts do not interchange.

These are extremely critical applications in power plants. Not just for revenue generation, but for the potential for personal injury. Evaluate each application with a full set of service conditions, pipe specifications, water chemistry, and incidental data such as whether there are any particles in the line and of what size (Some trims are not junk-tolerant and some are)
Most every major control-valve manufacturer has 6 or more anticavitation valves and a similar number of noise attenuation products. Each have specific features to solve specific problems. You definitely want to interface with a senior application engineer at the vendor while specifying these.
Valid sources: CCI, Emerson, Masoneilan, Valtek, (In alphabetical order)

 

[cian85]

Thanks for the advice Jim,
I´m actually just building a report on those three brands and their stacked disk designs which are recomended for both noise reduction and cavitation =)(they do have many more designs but it´s tortuous flow path that I´m interested in). More like a side by side comparison rather than any actual valve selection or sizing, so I thought polling around with actual users would be useful.

 

[rmw]

I have never used Koso but have had good results with Copes and some feel that the Drag valve wrote the book on the topic.

rmw

 

[terje61]

As mentioned by Jim, noise and cavitation are two different things.
1)
Noise is controlled by breaking down the energy of the pressure drop.
2)
Cavitation is controlled by avoiding that the lowest pressure in the valve (which is lower than the outlet pressure) remains above the vapour pressure.

I also think that staggered disc with a tortuous flow path is very different than a labyrinth trim were the flow from different paths collide into each other.

For noise control I have seen four different methods:
a) Tortuous flow path, with expanding flow areas.
b) Very small holes, resulting in very small yetstreams.
c) Labyrinth trims, with colliding flows.
d) Silencer box.

My experience is that all methods will reduce noise, because of power absorbtion in different steps. However not all methods are equally effective:

a) Tortuous flow path
Based on the Pressure x Volume should be equal principle. Although this works great for cavitation, this is not as clear regarding noise.
b) Small holes
Simple solution. Will shift the noise level to higher frequencies (non-audible). May cause problems with nearby ultrasonic equipment.
c) Labyrinth
3D labyrinths have the lowest noise levels at the same valve size. 2D labyrinths are about the same as the small hole principle.
d) Silencer box
Effective, but has a limited operating range. Tends to clogg in case of dirt in the gas.

When making comparisions I would compare all four.

Good luck,
Terje

 

[JLSeagull]

BTW they all make good strainers. Consider using small ports in clean service.

 

[JimCasey]

cian85,
you are looking at cage-type valve with tortuous flow paths.

Noise reduction valves allow the compressible flow to expand radially outward while limiting the velocity in any individual flow stream.

Cavitation "control" valves usually only have a single-stage cage with radial inward flow. Cavitation occurs in small jets and the jets meet in the center of the cage where they impinge upon each other and cause the bubbles to collapse where no damage is done.

Cavitation "Prevention" valves also use tortuous path to control velocity. High velocity means low dynamic pressure (per Mr. Bernoulli). The liquid flow is NOT compressible, so the flow is radial inward and the cross-section of individual flow paths does not expand progressively but it may cyclically change as part of the labyrinthine strategy. Any cavitation that occurs will be in the last stages(closest to vapor pressure) so the flows impinge and kill each other.

Regarding the most eminent JLSeagull's remark that they make good strainers: He's right, but valves are a lot harder to clean than strainers and if you scratch up the plug you get to write a check for many thousands of dollars. If there is possibility of particles in the liquid flow there are tortuous axial-flow valves that have much larger flow paths. Generically these are called "Lincoln Log" valves because of the way the plug is machined. Those valves can pass chunks larger than 3mm. Tricks with lincoln log-type valves and with other anticavitation valves are to take as much pressure drop in the initial stages as possible because those stages are less likely to cavitate. THe final stages then take gentle presure drops, thus avoiding cavitation.

Most of the difference between styles involves packing as many stages of pressure reduction as possible into a given volume.

Back to my original advice: Don't lump together anticaviation valves and noise attenuation valves. They may look a lot alike but they work very differently. Also seek experienced professional guidance in selecting valves for critical applications.

 

[JimCasey]

A nice article about cavitation prevention in this month's Valve magazine:

http://www.valvemagazine-digital.com/valvemagazine/2009summer/?folio=30

 

[fwcatr]

Depending on the size of the valve, and what your research is intended for, you might want to think about verifying, by testing, the aero and/or hydro noise performance of the control valves along with veryifying the capacity characteristics. Each valve company may use the IEC method for predicting noise or use their own proprietary method. Some proprietary noise prediction methods are based on years of experiemental data and some are not. If a control valve will be applied in a high risk, high dollar application, noise testing and capcity characteristic costs are negligible. Just make sure if you go the noise testing route you find a reputable organization that has experience in control valve noise testing.

 

[UHoustonMSME]

IEC has solid method for noise prediction. In valves with multi-stage trim, IEC says to calculate jet noise generated at last stage. The more stages, the less noise. The CCI DRAG disk design uses this principle and can have 10, 20, or even 40 stages to control noise.

Small port trims can clog. Ask your supplier about options for known dirty service applications. They may be able to include some features that keep contaminants out of the flow path and prevent clogging problem.

 

[fwcatr]

The blanket statement that more stages produces less noise can be erroneous. If the stage actually takes a pressure drop, the statement is correct. If the stage does not take a pressure drop, the statement is erroneous.

Even though a noise attenuation trim can have many, many stages, if they don't produce pressure drops across each stage, the pressure drop will be taken across the whole cage element, which will not attenuate noise.

One must be very careful filtering through sales propaganda to decipher the real dynamic flowing phenomena going on.

Controlling the flow path of cage exit jets is important too. Exit jets that combine will produce more noise than exit jets that don't.

 

[valveguru]

Recognize that there are a number of different manufacturers that produce multiturn trim for both noise and cavitation control. The comparison of trim design has a number of different considerations:
- Number of stages and expansion between stages
- Flow passage design
- Strucural ligaments in the trim itself
- Attachment method and materials to hold the disks together
- Number of disks provided in the disk stack
- Materials used for the disk stack and heat treatment supplied.
- Flow passage size used
- Characterization between disks in the disk stack

The trim design is only one facet of the valve design. Actuator loading for shutoff and control, body configuration and design, and method of loading trim to prevent vibration and separation of the disks are all critical in the design of the equipment.

Finally, knowledge and experience in the industry and application and being able to vary design of trim and valve to meet the specific requirements is critical. Also, being able to support the product once it is in the field is critical to the end user selecting a vendor. I have seen catalogs with CAD generated pictures that claim the vendor can build multiturn valves up to 36" and 2500# rating out of exotic materials. An investigation of the vendor shows that they are a small house with 4 years of experience in general service valves with 1 engineer and 5 total employees. All suppliers need to be able to provide multiple installation references with 5 years or more of active experience.

 

[MattC1234]

It is widely though that CCI developed the first disc stack design trim, however many other companies have improved this design since the Drag trim, Valtek's tigertooth although seemingly good is often overspeced and requires larger body capacities in order to "fit in". I was not aware that Emerson had a disc stack design, and i would avoid Koso's as this is a very recent addittion to their catalogue and still i understand in the development stage. One of the best manufactures of Severe Service control valves is Severn Unival / Severn Glocon. Their Labyrinth trim design is quite impressive and have specially designed a similar trim in Tungsten Carbide for Sand/ Solid contamination service.

Cavitation is the temporary formation of bubbles followed by their collapse, caused as the pressure of the liquid drops below the vapour pressure before it recovers back above. Multiple stages of pressure letdown are required to form a stepped controlled reduction of the pressure of the fluid across the trim, to prevent it from dropping below the vapour pressure. although Caviation is not really associated with noise, it can be a factor for it.

Noise is generally associated with high trim energy levels usually occuring with high flows (high outlet velocities above 10m/s) which is usually the case at high pressure drops. Often the problem is not helped by flowing the fluid in the wrong direction, which is a problem more so on gas applications.

I would certainly contact Severn Unival for more information, they are well known in the UK as experts in severe service applications (which usually is the case when offering disc stack trim designs)

 

[JimCasey]

All the trims that have been discussed here work by keeping the velocity low. Noise is generated by having an excessive pressure ratio between any 2 stages, and that pressure ratio drives the flow sonic. Sonic flow causes shock waves, and those are noisy. Divide the pressure ratio into small steps, velocity stays low, and the noise stays low too. Compressible flows de-compress as they flow through the valve so the ports must increase to correspond with the increased volume. Usually this means radial outward flow.

Cavitation is also caused by velocity. Bernoulli pointed out that pressure drops as velocity increases. Get the velocity too high, the pressure drops to the vapor pressure of the liquid, and the liquid flashes to vapor/liquid flow. then when it slows, the pressure recovers, the bubbles collapse, and we have cavitation damage. Liquids are incompressible and do not expand (unless bubbles form). If bubbles form they are more likely to form in the final stage(s) because those stages are at lower pressure nearer to the vapor pressure of the liquid. Frquently anticaviation valves have radial flow INWARD so if the final stage cavitates, the bubbles will crash into each other and collapse instead of damaging something expencive.

I am surprised to see Copes, Hammel Dahl, and CCI compared. That's like comparing Ford, Chevy, and Ferrari, in my humble opinion. It seems to me that Copes and Hammel have not noticeably advanced technology since the 70s. Again, my opinion, that CCI's technology is in having a strong applications engineering group and their Valve Doctors do pretty well in custom designing a trim to a particular application. This is why, in my first message, I suggested consulting a factory applications engineer. By the time you have a problem big enough to spend the kind of money you'll have to spend for a CCI valve, you have a lot of productivity riding on getting the application right.

Still, CCI does not provide the answer to every situation, and there can be much less expensive answers to a given question. That is why I mentioned other manufacturers such as Leslie, Valtek, Masoneilan, and Fisher. But you're not going to be able to pull an answer up by reading their catalogues. Their local sales guys may be great, but for this kind of application you need the highest level of confidence. You'll need to talk to the factory application engineers who live this stuff every day and they either design the valves or sit 3 desks over from the designer. They have access to the trick parts and to the understanding about where to use them.

 

[valveguru]

Normally I would not do a direct vendor to vendor comparison on an open formum like this, as I believe that this forum should be a purely technical basis. However, MattC1234 has stated some points regarding vendors and equipoment history that should be cleared up.

1) CCI was the first manufacturer to supply multi-turn trim 40 years ago, and continues to make improvements on equipment today.
2) CCI was the first manufacturer to produce and supply multi-turn tungsten carbide disk stack trims. Original equipment was supplied in 1996, and hundreds of units supplied and are operational.
3) Unival, Severen, Introl, and KOSO are affiliated.
4) Catalogs describing the multi-turn technology with the option for tungsten carbide are relatively new to these afffiliated companies. I do not find any previous to 2006.

Tungsten carbide is an entirely different engineering material, and the design considerations are quite unique. Applying it to diffent applications such as wellhead chokes, separator level control, pump recycle, wellhead injection control, pipeline pressure reduction, methanol injection, etc. all have special application considerations.

Ask for references, time in service, past history, etc. when selecting severe service valve suppliers.

 

[MattC1234]

ValveGuru... in a few words you are incorrect!

"unival,severen,introl and KOSO" are NOT affiliated!

Unival is SEVERN Unival which is part of the Severn Glocon Group.

KOSO Kent Introl is a seperate company to Severn Glocon and in fact one of their major competitors!

As i said Koso's disc stack trim design is very new maybe around 2006, however Severn has had their Disc Stack design since the mid 90's.

I do agree with your other statements however, CCI was the first and i would recommend you ask for service history when looking for severe service valves!

 

[shameer786]

Hi All,good topic to discussed with.I know KOSO Hammel originally NIHON Koso,japan.They have good technology for cavitation and noise problem with challenging price too.


my question is these disk stack technologies can reduce noise level in flashing conditions?

best regards
shameer

 

[UHoustonMSME]

Shameer - thanks for the good question! Answer is: probably!

You can use multi-stage trim to control trim exit velcoity head (dynamic pressure). This approach should reduce the amount of energy which is converted into noise and vibration in flashing service.

I have heard that some plants report less noise and vibration in flashing service after installing the Drag design, particularly on primary superheater bypass (202) and feedpump recirculation.

Unfortunately there is no standard method for calculating noise in flashing service in the ISA or IEC. Some suppliers have created their own method for this. I suggest you ask your suppliers for references to keep them honest.

 

[JimCasey]

If you run flashing service through a multistep cage, at least some of the intermediate stages will cavitate. In the words of the ghostbusters, "That would be bad." Severe flashing services should flow over the seat in an angle valve, and discharge thru a venturi tailpiece. In slightly less severe applications such as heater drains, flow the water through an eccentric rotary Plug valve with the shaft upstream. Calculate the density of the downstream mixture and use that to size the downstream pipe for reasonable velocities. Or mount the valve directly on the nozzle of a flash tank or other vessel so the vapor can expand at low velocity without causing damage. Stainless or CrMo resists erosion in flashing services. If your downstream piping and valve are merely carbon steel, invest in a lot of mops, 'cause the high-velocity droplets will erode CS and eat holes in the plumbing. Chromium content helps reduce damage from flashing.