Butterfly valve Vs Sluice valve in Fire Piping system

[rgprasannakumar]

All,
Can you please explain, how in fire piping system, butterfly valve and sluice valve differs functionally? To my knowledge, both are functionally same. But some of my colleagues are saying, sluice valve are much safer than butterfly valve. Also in sluice valve we have less friction loss. For cost reduction also, people are suggesting to go for butterfly valve. Except for cost reason, I can't stand my point in Sluice valves. Is safety the only point for going with sluice valve? Please help.

 

[stanier]

Butterfly valves are quite acceptable for such service. Downside is you cannot maintain them in situ as you can a sluice valve. you will find vistaulic do a range of such valves with their patent connections that are part of their fire system of piping.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[rgprasannakumar]

Thanks for putting some lighting on the subject. Now apart from safety part of view, maintenance is another point to be considered.
How sluice valve can be maintained in-situ and why can't butterfly valve?

 

[stanier]

It has been known for butterfly valves to jam in the open position making them impossible to remove from the pipeline unless there is a dismantling joint nearby. The valve has to be eremoved to maintain the integral seal.

A sluice valve will invariably be fully open or closed. The top works can be removed to get tot he plug and seat.

One thing that you might consider is that a butterfly valve is not considered to be a form of isolation when it comes to double isolation philosophy. Opening of a butterfly valve can be rapid as smaller vavles are quater turn and larger valves pass 80% of flow when 20% open. Hence waterhammer may be of concern.

Another matter to consider is that butterfly valves come in wafer, lugged and flanged tyoe. A wafer type cannot be used for isolation if the downstream piping is removed. this issue does not arise with sluice valves as they are fully flanged.

Suggest you start looking at some valve design drawings on the various manufacturers website and you can see the difference in the design.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[rgprasannakumar]

That really helps a lot.
Thank u!!

 

[gerhardl]

Hello both!

One additional point: by firefighting it seems that you both are talking about 'normal pressure, normal sized firefighting systems', say up to 250 mm (6 inch) size absolutely max and 10 bar max pressure? And 'sluice' as normal soft-seated gatevalves?

In this case I fully agree, assuming valves to be selected on long-term quality and references, not on price!

You could, however, for critical and isolation valves consider double flanged, double eccentric BFL valves with gears. This will be more dependable and with far longer life, but at considerably higher price. Especially for motor valves, or higher sizes and pressures, this should at least be considered.

 

[rgprasannakumar]

Hey gerhardl:
Thanks for the additional info. As you know, we are talking about the fire-fighting system with working pressure maximum of 88 Metre water of column (8.8 bar). However if at all my system undergo such high pressure, I will consider your point surely.
Thanks

 

[hsbcn]

Sluice gate valves, or parallel slide gate valves, also knife gate valves, are the the standard gate valves's older brother, used in larger pipe-diameter applications. Their shut-off is slower than butterfly valves, but their shut off is also more prone to a good seal. You would opt for a sluice gate for safety, and for a butterfly valve for price. If you do decide to go for a butterfly valve, I'd go with gerhardl's suggestion on double flanged, both for life and for safety. That will increase price, so if comparing, compare the sluice gate with a decent butterfly valve, and then decide. Factor in shut-off time in your considerations, if you're looking at a millisecond-critical application.

My focus is on valve stockists in the us and uk who supply duplex and super duplex valves, and inconel and hastelloy valves, plus titanium, alloy 20 and 904L valves.

 

[rconner]

If/when you want to run anything other than water through a pipeline (e.g. pipeline pigs for removing debris or anything left or crawling in pipeline, or any sorts of present or future instruments etc.) this will generally be easier when you have full-port opening valves.