Ductile iron disk butterfly valves Vs stainless disk

[hyari]

Hi ,

what is the main difference in DI disk and stainless steel disk of butterfly valves ? in case the applications are TSE OR SEWAGE
and what is the advantage / disadvantage of both

Thx
Ahmad

 

[mk3223]

Either DI or SS disc used in the butterfly valve construction may be compatible to the process fluid of the sewage system for the corrosion protection.
In case of the TSE, the use of the bronze or monel disc may be considered for the valves.

 

[bimr]

A butterfly valve should not be used in sewage applications. Suggest you consider a full port plug type. Materials of construction of valves will depend on the characteristics of the water.

 

[ashtree]

Butterfly valves should not be used in sewage because of the presence of solids, rags , hair , plastics etc in the flow. When the butterfly valve is in the open position it is sitting edge on in the middle of the flow and these solid materials can become caught on the disk. This causes a reduction in flow resulting in a blockage and will prevent the sealing of the valve when trying to close it.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[gerhardl]

Hi all,

I agree with all posts above.

Preferable for sewage is in my opinion gatevalves or knifegate valves of good quality.

For us no-native English-speaking people I found, among 68 meanings of TSE, 'Treated Sewage Water'.

You might use BF-valves for filtered sewage water, but with all weaknesses mentioned in other posts. Use only top quality constructions with coated discs and top quality stem sealing constructions. To be preferred in addition is double or triple eccentric types. SS discs may be used, but quality coated discs are cheaper and at least equal in corrosion resistance to SS.

For butterfly valves for TSE there is no practical difference other than price for materials for house or disc regarding strength, if correctly dimensioned and constructed / protected.

ANYWAY : Best and cheapest construction for TSE smaller valves is gatevalves from 50mm to (say about) 200-300mm). Inner of gatevalves must be high-quality epoxy coated or coated in rubber, gates rubber coated, stem SS, and no pockets where dirt can assemble. If the pipeline is constructed with spaces for wafer/short length BF valves use knifegate in stead.

Above this size 200-300 mm knife-gate valves will normally be cheapest. Pricedifference and weight between knifegate- and gatevalves will increasing exponentially (say) above 500mm. Knifegate valves must have constructions with at least gates in SS, type for flow and thightness in both directions, and no pockets.

(Advice: More details on technical questions will always give better and more precise answers. Are we talking 200 or 2000mm dimensions? Flow, pressure, and grade/size/amount of particles?)

Good luck!

 

[cvg]

TSE Treated sewage effluent, presumably should not contain solids and rags. Sewage would typically be assumed to be untreated and would contain solids. these are two different applications and the type of valves would be different for each

http://ese.dgtlpub.com/2013/2013-06...lve_for_wastewater_treatment_applications.pdf