Large Aluminum RPZ Backflow Enclosure Installation

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Specifying protection for large reduced pressure zone (RPZ) valves means making decisions well before the equipment arrives on-site. Pipe diameter, number of assemblies, meter configuration, clearance requirements: each one shapes the enclosure spec. Get it wrong and you're looking at failed inspections or an installation that can't be safely tested and maintained for the life of the system.

A Pennsylvania design engineer came to Safe-T-Cover with a project that pushed the limits of standard enclosure sizing and a site condition that ruled out underground vaults entirely. The solution was a 390-square-foot large aluminum enclosure, 15 feet wide, 26 feet long and 12 feet tall, shipped as a modular kit and assembled on-site by a standard crew.

The above-ground approach eliminated confined space classification, flood risk and the long-term maintenance burden of vault access. Here's how the project came together.

About The Project

Industry:

Municipal Water / Commercial Plumbing

Project Type:

390-sq.-ft. above-ground enclosure

Equipment:

Dual 12" RPZ backflow preventers with a 12" meter and strainer

Mounting:

Outdoor, slab-mounted

Outcome:

A compliant, accessible, freeze-protected above-ground structure

The Challenge

FENDING OFF FREEZE

When the design engineer on this Pennsylvania project set out to protect a large-scale RPZ installation — dual 12" backflow preventers, a 12" meter and strainer — standard solutions fell short. The project demanded a large aluminum enclosure that could house complex equipment above grade while meeting clearance, freeze protection and code requirements.

Underground vaults were off the table. Confined space classification under OSHA creates access and liability issues, and flood risk to submerged valves introduces a direct cross-connection hazard.

The designer needed a durable, corrosion-resistant solution that could:

Offer freeze protection, drainage and structural integrity
Provide a minimum of four feet of clearance around all equipment for annual testing, maintenance and repair access
Be installed quickly by a standard contracting crew without specialized tools

Without the right enclosure manufacturer and partner, the risks were equipment failure from freeze damage, extended installation timelines and long-term liability exposure for the water system owner.

The Strategic Approach

SPECIFYING AN ABOVE-GROUND ENCLOSURE DESIGN

Safe-T-Cover's design team worked with the project engineer to identify the right configuration from the large enclosure series — a line developed specifically for growing demand for above-ground protection on large-diameter RPZ and meter installations.

Above-ground aluminum enclosures represent best practice for this class of installation, and this project reflected a broader industry trend: water jurisdictions and designers are moving away from vaults in favor of safer, more accessible above-ground structures.

The design process centered on three priorities:

Right-sizing the enclosure to meet layout and clearance requirements
Engineering thermal performance to protect against freeze
Ensuring ease of access for the testing and maintenance crews who would work with this equipment for decades

The Solution

CUSTOM ALUMINUM ENCLOSURE READY TO ASSEMBLE

A Large RPZ enclosure with multiple removable panels in Pennsylvania

Safe-T-Cover shipped Model LES 180-312-144 — a 15-foot-wide, 26-foot-long, 12-foot-tall modular aluminum enclosure — to the Pennsylvania jobsite as a ready-to-assemble kit. At 390 square feet of interior space, this large aluminum enclosure was engineered to meet the full complexity of the piping layout while remaining practical to install and maintain.

The elements chosen for this application included:

Six lockable access panels positioned for convenient entry and security around the dual-RPZ layout
Four feet of clearance on all sides of the equipment to meet annual testing and maintenance access requirements
Three fan-forced heaters maintaining a freeze-proof internal temperature of +40°F, rated for outdoor temperatures as low as -30°F
Lightweight modular panels shipped as a ready-to-assemble kit, installable by a three- or four-person crew with conventional hand tools
ASSE 1060 Class 1 certified construction — meeting industry benchmarks for freeze protection, drainage, structural integrity and secure access

The above-ground design also housed the water meter in the same enclosure — a growing trend as jurisdictions recognize the confined-space risks and long-term maintenance burdens of underground meter vaults.

The Results

The LES 180-312-144 was shipped on time and delivered a fully compliant, above-ground installation that met all project specifications for access, freeze protection and code compliance.

Size Your Large Aluminum Enclosure

Whether you're protecting an RPZ or designing a complex large-scale installation, Safe-T-Cover's engineering team can help you order the right above-ground enclosure solution. We produce enclosures in a range of sizes — small, large and custom — based on your project's needs.