Nibco 4853-KO Flush Closet Fla...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$21.60
Nibco 4853-KO Flush Closet Flange with Pipe Stop and Knockout - PVC DWV

Nibco 4853-KO Flush Closet Flange with Pipe Stop and Knockout - PVC DWV

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Model: K355720

In Stock (leaves warehouse same day if ordered before 3pm ET)

$21.60
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The PVC DWV flush closet flange features a pipe stop and fits inside 4-inch DWV pipe and over 3-inch DWV pipe. The flush closet flange also features a knockout to prevent debris from entering the draining system. The closet flange is secured to the floor of the dwelling so that a toilet can be affixed to it and allow for a pipe connection (under the floor) to continue the piping for evacuation of the used water. Please refer to NIBCO technical data sheets and catalogs for engineering and installation information. Polyvinyl chloride (PVC) is the most frequently specified of all thermoplastic materials because of its light weight, durability, and cost-effectiveness. PVC DWV is easy to install and is joined by solvent cementing or threading. PVC fittings exhibit high corrosion and chemical resistance and will not rust, scale, pit or corrode. NIBCO® plastic fittings are backed by a 5-year limited warranty. Because of its longstanding reputation for innovation and precision in design and manufacturing, NIBCO is the preferred brand in the industry.

  • Maximum service temperature 140-DegreeF
  • Do not test or use with compressed air or other gases
  • ASTM D2665 and D3311
  • NSF/ANSI Standard 14
  • NSF U.P. Certified

Plastic Fittings Installation Instructions

Manufacturer Resources

NIBCO Plastic Fittings Catalog

Product Specs

All Application(s):
DWV Drain / Waste / Vent
All Basic Material:
PVC - Polyvinyl Chloride
Classification:
PVC DWV Closet Flanges
End Connection:
Solvent Weld
Pipe Schedule:
40
Plastic End Connection Type:
Hub or Spg (with pipe stop)
Product Group:
Fitting
Product Type:
PVC DWV Closet Flanges
System Use:
Commercial Plumbing, Residential Plumbing
Product Subgroup:
Closet Flange
Department:
Plumbing
Product Color:
White
Product Width:
7 in
Product Weight:
0.8 lb
Product Length:
7 in
Country Of Origin:
United States
Product Height:
2.75 in

Nibco K355720 – Frequently Asked Questions

1) Does the Nibco 4853-KO closet flange fit 3 inch or 4 inch DWV pipe?
Both. The 4853-KO flush closet flange fits inside 4 inch DWV pipe and over 3 inch DWV pipe, so one part covers either rough-in. That dual fit comes from the hub/spigot design with an integral pipe stop, which sets the depth the pipe bottoms out at.
2) How does this Nibco PVC closet flange connect to the drain pipe, glue or threads?
Solvent weld. The 4853-KO is a solvent cement joint on PVC DWV pipe, so you need PVC primer and cement, not a threaded or gasketed connection. Nibco's PVC DWV fittings can be joined by solvent cementing or threading as a product family, but this flange is specified as a solvent weld end connection.
3) Can I use the Nibco 4853-KO on a commercial job, and what standards does it meet?
Yes, it's rated for both commercial and residential plumbing. The flange is manufactured to ASTM D2665 and D3311 and is listed to NSF/ANSI Standard 14, plus NSF U.P. Certified. Pipe schedule is 40. Those are the listings an institutional or MRO spec writer normally asks for on a DWV fitting.
4) What is the knockout on the 4853-KO closet flange for?
It's a temporary blank across the flange opening that keeps construction debris, mortar and trash out of the drain line during the build. Knock it out when you are ready to set the toilet. Handy on new construction and multi-family jobs where the flange goes in long before the fixture.
5) Is this a flush-mount closet flange or one that sits above the finished floor?
Flush. The 4853-KO is a flush closet flange, meant to be secured down to the floor of the dwelling with the toilet bolted to it and the drain continuing below the floor. If your rough-in leaves the pipe high and you need to raise the toilet seal, a flush flange is the wrong geometry and you would look at a spacer or an offset/raised flange instead.
6) What is the temperature limit on this PVC DWV closet flange?
140 degrees F maximum service temperature. That covers normal sanitary drainage. Do not test or use it with compressed air or other gases. If the line carries repeated high-temperature discharge above that limit, PVC DWV is not the right material.
7) What color is the Nibco 4853-KO, and will it match my existing PVC drain lines?
White PVC, which is the standard color for PVC DWV drain, waste and vent systems, so it matches typical white PVC DWV pipe and fittings. It is not ABS; black ABS systems need an ABS flange or a listed transition, not a solvent weld to PVC.
8) What is the manufacturer part number for the Nibco 4853-KO closet flange?
Nibco lists it as the 4853-KO, PVC DWV flush closet flange with pipe stop and knockout, part number K355720, sized for 3 inch or 4 inch pipe. That's the number to quote when you are matching a spec or reordering across a fleet of units.
9) Why choose PVC for a closet flange instead of metal?
PVC will not rust, scale, pit or corrode, and it carries high corrosion and chemical resistance, which matters on a part bolted to a wet bathroom floor. It is also light and quick to install with solvent cement. Cast iron or brass flanges are the alternative where you are tying into an existing metal stack rather than PVC DWV pipe.
How fast can I get the Nibco K355720 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Nibco K355720 come with a warranty?
Absolutely. The Nibco K355720 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Nibco K355720?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
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