Sub Zero Covers
Three green insulated backflow covers in a gravel bed outside an office building — a large double-check detector assembly, a mid-size assembly, and a small companion cover.
Office campus — a whole backflow fleet on one cover line

By assembly and size

10" double check backflow cover

10" double check backflow cover sizing starts with the assembly on the tag. At 10", 7 double check assemblies from the brands we pattern for are common: Watts 757, Watts 774 / 774DCDA, Febco 870V / LF870V, Zurn Wilkins 350 / 350A / 350AST, Ames 2000SS, Ames Colt C200, and Apollo / Conbraco DCLF4A large. The price list maps this pipe size to one stock cover, and the published dimensions below say which one to pull.

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What "10" double check" covers on a counter

Double check valve. At 10" the assemblies your customers bring in are Watts 757, Watts 774 / 774DCDA, Febco 870V / LF870V, Zurn Wilkins 350 / 350A / 350AST, Ames 2000SS, Ames Colt C200, and Apollo / Conbraco DCLF4A large. They are not the same size: the Febco 870V / LF870V is 42.5" end to end and the Zurn Wilkins 350 / 350A / 350AST is 63.875", so "a 10" double check" is not a single envelope.

The stock cover for 10"

The April 2026 price list maps 10" to 130 × 55 (DS13055), with the N-shape NS10 for N-pattern installs. That cover was built around this size class; the table below shows how each assembly sits inside it.

The base can close

A double check does not discharge, so the cover can close fully to the pad. That holds ground heat in and gives wind nothing to lift.

When to measure instead

Unions, strainers, OS&Y gates, and wall-tight mounts all move an assembly off its spec sheet. If the tag is gone or the install is odd, measure it or send photos for a custom cover. For the type as a whole see double check covers; for another size, start at the fitment hub.

Sub Zero Covers sells through distributors only. Distributor accounts see pricing and availability in the portal; everyone else orders through their supply house, or applies for distributor access.

Assemblies at this size

10" double check valve assemblies and the cover that fits

Dimensions in inches from each manufacturer's spec sheet with standard shutoffs. Length end to end; heights from the pipe centerline. The cover column is the closest stock fit by published length; confirm against the assembly in front of you.

AssemblyLengthAbove CLBelow CLClosest stock cover
Watts 75757.75"45.75"8.1875"130 × 55 (DS13055) · N-shape NS10
Watts 774 / 774DCDA55.5"45.75"8"130 × 55 (DS13055) · N-shape NS10
Febco 870V / LF870V · N-pattern42.5"——N-shape NS10
Zurn Wilkins 350 / 350A / 350AST63.875"24.75"8.5"130 × 55 (DS13055) · N-shape NS10
Ames 2000SS55.5"45.75"8"130 × 55 (DS13055) · N-shape NS10
Ames Colt C20057.75"45.75"8.1875"130 × 55 (DS13055) · N-shape NS10
Apollo / Conbraco DCLF4A large62.3"45.8"11.1"130 × 55 (DS13055) · N-shape NS10

Common questions

Which cover fits a 10" double check?
The 130 × 55 (DS13055) is the price-list match for 10". N-pattern installs take the N-shape NS10 instead.
Do all 10" double check assemblies take the same cover?
Not always. At this size the published lengths run from 42.5" (Febco 870V / LF870V) to 63.875" (Zurn Wilkins 350 / 350A / 350AST). Order by model.
Is this a heated enclosure?
No. Sub Zero Covers are insulated, unheated covers (R-13 standard, R-30 extreme weather). They are not ASSE 1060 listed enclosures. Where a spec calls for a Class I heated enclosure, ask sales before quoting.

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