Sub Zero Covers
Tan insulated backflow cover protecting a fire-line assembly along a commercial fire lane, with tamper switches, supervisory chain, and the FDC connection exposed above the cover.
Commercial fire lane — tamper switches stay accessible

By assembly and size

2½" DCDA backflow cover

2½" DCDA backflow cover sizing starts with the assembly on the tag. At 2½", one DCDA assembly from the brands we pattern for is common: Deringer (Ames) 30. 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 "2½" DCDA" covers on a counter

Double check detector assembly. At 2½" the assemblies your customers bring in are Deringer (Ames) 30. The Deringer (Ames) 30 publishes 18.7" end to end.

The stock cover for 2½"

The April 2026 price list maps 2½" to 70 × 40 (DS7040), with the N-shape NS3 for N-pattern installs. That cover was built around this size class; the table below shows how each assembly sits inside it.

The detector bypass

DCDA assemblies carry a metered bypass along one side of the mainline. It adds width the stock cover usually accommodates at this size, but send a photo showing the bypass side before quoting; a custom pattern ships in 3–5 business days.

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 DCDA 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

2½" double check detector assembly 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
Deringer (Ames) 3018.7"7.1"2.9"70 × 40 (DS7040) · N-shape NS3

Common questions

Which cover fits a 2½" DCDA?
The 70 × 40 (DS7040) is the price-list match for 2½". N-pattern installs take the N-shape NS3 instead.
Do all 2½" DCDA assemblies take the same cover?
At this size the assemblies we pattern for sit inside the same stock cover. Confirm shutoff type and riser height.
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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