Sub Zero Covers
Two tan insulated backflow covers on a concrete pad above a hillside neighborhood — a full-size assembly cover beside a smaller companion cover, with the red gate valves left exposed for access.
Hillside install — full assembly plus companion cover

By assembly and size

2" RPDA backflow cover

2" RPDA backflow cover sizing starts with the assembly on the tag. At 2", one RPDA assembly from the brands we pattern for is common: Deringer (Ames) 50. The price list maps this pipe size to 3 stock covers, and the published dimensions below say which one to pull.

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What "2" RPDA" covers on a counter

Reduced pressure detector assembly. At 2" the assemblies your customers bring in are Deringer (Ames) 50. The Deringer (Ames) 50 publishes 22.1" end to end.

The stock covers for 2"

The April 2026 price list maps 2" to 30 × 24 (DS3024), 36 × 24 (DS3624), and 42 × 24 (DS4224). The table below orders them closest fit first for each assembly: the cover should clear the end-to-end length across both shutoff handles with room to close at the base.

Relief valve drainage

Every assembly on this page has a relief valve that discharges downward from under the body. Leave that path open. Close the cover to the pad around the assembly, never under the relief port.## The detector bypass

RPDA 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 RPDA 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

2" reduced pressure 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) 5022.1"9.3"8.7"30 × 24 (DS3024)

Common questions

Which cover fits a 2" RPDA?
One of 30 × 24 (DS3024), 36 × 24 (DS3624), and 42 × 24 (DS4224), chosen by the assembly's end-to-end length. The table above names the closest fit for each RPDA at this size.
Do all 2" RPDA 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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