Is PLUG VALVE better than GATE VALVE on storm drainage piping?

[sportsnut44]

I have a storm drainage system that has a flow splitter to some treatment devices. Gate valves are shown on each side of the flow splitter for either spill control or maintenance purposes, i.e. flow to treatment devices can be shut off while performing maintenance. I normally show gate valves for this purpose. I had a peer tell me to use a plug valve instead, as it is better at creating a good seal when flow streams in drainage systems have some grit and such. However, I am concerned about the reduced port area that would restrict gravity flow, and I have heard plug valves are very hard to operate and if they are not maintained can be impossible to budge later on. Comments?

 

[RWF7437]

Probably best choice for storm or waste water, is "None".
Gate valves are NOT designed to be used as throttling or flow control vales . They are intended to be shutoff valves to remain fully open or fully closed.

Other types to consider are :

Plug Valve
Slide Gates
Swing Gates
"Duck bill: Tide or backwater valves
Tainter Gates

Several valve makers offer Free Advice including
Globe
Golden
Crane
Many, many others

Several standards and professional groups such as AWWA, WPCF,
ASCE
The Ten State Standards
and your local agencies having jurisdiction will also offer advice, even if not asked.

Apologies for the acronyms.

Prepare for a long Google Session and good luck.

 

[sportsnut44]

The gate valve is used as a shut-off valve in this application, not a control valve / throttling valve. So, the question is whether a plug valve is better than a gate valve in a storm water system when shut-off valves are required by regulatory authorities upstream and downstream of water quality devices. I've always used gate valves in the past, and don't like the reduced port size of a plug valve, but like I said, peer said he prefers plug valves so I'm trying to find out the advantages and disadvantages of going with a plug valve in this situation rather thana gate valve. Thanks in advance for your help.

 

[hydrae]

Double disk gate valves will not go drip tight because the sediment in the groove will prevent the valve from fully closing. Proper operation in a pressurized system with flow can clear the debris. (close, open 5 turns, close, open 3 turns... until the valve will not close any tighter)

Resilient seat gate also know as wedge valves will have less of a problem since there is no groove but if there is debris in the gate area that cannot be crushed or flowed out, the valve will still leak.

Plug valves are better at sealing against this problem because they slide the debris away (or attempt to) but if the debris is tightly adhering to the sealing surface it make the valve very hard to operate.

 

[nackra]

what size valve are you planning to use?

I suspect that a gate or wier is better device

 

[sportsnut44]

Valve size I'm talking about is 8" and 12", but same question for sizes up to 24".

So far biggest advantage I'm hearing for plug valves is the ability to still provide a good seal in a system where solids may drop out of the flow stream, and biggest disadvantage is the potential for them to be difficult to impossible to operate if not well maintained / lubricated.