Horizontally Mounted Gate Valve - roller & scraper

[alexcmmi]

Are rollers and scrapers used in large diameter (>12")resilient seat gate valves that are mounted horizontally? I know they were used in double disc, but what about resilient seat?

What happens to sediments that might deposit on the seating surface? How is this removed?

Appreciate any tips or advice.

Thank you

 

[pennpiper]

Wow! You learn something every day. I had never heard of this in all my 45 + years of piping.

http://www.ejprescott.com/products/ValvesTap/LargeDiameterDiscValves.pdf

 

[gerhardl]

What type of gate valve and for what purpose?

Depending of service type, pressure and fluid, you would be able to select from a wide range of constructions.

The upper end being special construction knife-gate or o-port all stainless steel valves for high-pressure, high temperature liquids with a high degree of solids sticking on the blade. Built in scraper effects in sealing constructions.

The lower end all resilient normal gates against for instance epoxy covered body?

Interesting if you could expand a bit on what your real problem is.

 

[alexcmmi]

Thansk for the responses.

The application is a raw water intake from a Ranney collector well (riverbed filtered river water). Temperature is 40-60F and max pressure is ~140 psi. Pretty standard water utility application (sorry, kinda boring).

I am just worried about sand and sediment that will pass through into the collector wells and that might settle in the water main.

We are using resilient wedge gate valve. In the past, the double disc had a roller and scraper, where as the resilient wedge does not. My question is should I be worried about sediment in the seat not allowing the valve to be bubble tight. Maybe my concern is unwarrented.

Thanks again.

 

[gerhardl]

A European / Scandinavian approach would be to use resilient seated gate valves, where the gate itself is compleately covered in elastomere (normally EPDM or NBR), stem stainless, non-rising stem, stem nut in softer gun metal allaoy, stem nut 'floating' inserted in upper part of wedge, guides for wedge incorporated in housing, in best constructioned valves with elastomere (PTFE or similar) sidewise guides incorporated or mounted in housing wall.

Full bore, free bottom, vertically mounted, stem up.

This type is also used for sludge and waste water, and will normally give no problems.

For larger diameters, say 20 inches and above, (but also for smaller if automated), double eccentric, double flanged butterfly valves, epoxy lined, soft sealed, certified for drinking water, shaft mounted horizontally, will be a cheaper and lighter choice.

For both types quality in valves should weigh more than price.

Good luck!