In 1996, the American Society of Sanitary Engineering released a new standard - ASSE 1060 - to regulate the budding backflow enclosure industry. Enclosures built before then may have had too little or too much insulation or heaters that weren't safe. Sometimes they were simply a fiberglass box placed on top of the valves. Before the standard was released, drainage was as much a problem with enclosures as it is today for indoor RPZ backflow preventers. Back when it was newly released, this article outlined most of the problems and how the new standard would help solve them. It's especially interesting that Plumbing Standards Magazine was publishing information on RPZ discharge rates and the dangers of confined spaces in 1996, and these are the same problems we're facing today.
The standard has since been updated in 2006, adding more detail to the testing. It also clarified that equipment enclosures designed for "fluid conveying components" needed to pass this standard, not just "backflow preventer enclosures." It was updated more recently again in 2017, changing some of the requirements around heaters, and adding additional testing requirements.
The ASSE recommends that these enclosures are installed in a way consistent with local codes, most of which require the cover to be ASSE certified. Products can only be ASSE approved if the manufacturer has applied to the ASSE and had the product tested in their lab. The process can take up to 60 days and back in 1996 it could cost up to $25,000. Once the product has passed the test, like Safe-T-Cover's products have, they gain a seal of approval. Here's what that approval means.
Class I Freeze Protection Enclosures Heated
Enclosures designed and constructed to maintain a minimum internal temperature of 40°F with the external temperature of -30°F with a minimum Thermal Resistance (R) Value of eight (8.0).
Class I-V Freeze protection enclosures for pressure and atmospheric vacuum breakers.
Class II Freeze Retardent Enclosures may or may not have a Heater
Enclosures designed and constructed to maintain a minimum internal temperature of 40°F for a 24-hour period with a minimum Thermal Resistance (R) Value of eight (8.0).
Class II-V Freeze protection enclosures for pressure and atmospheric vacuum breakers.
Class III Non-Freeze Protection Enclosures No Heat
Enclosures designed and constructed with NO freeze protection and NO minimum Thermal Resistance (R) value.
Class III-V Non-Freeze enclosures for pressure and atmospheric vacuum breakers.
2.0 Structural Strength
All classification enclosures must designed to support a minimum vertical load of 100 pounds per square foot (100 psf).
3.0 Drainage Capability
All classification enclosures must be designed to discharge water from within the enclosure to prevent submerging the equipment. The depth of water rise within the enclosure shall not exceed 8 inches during full discharge of a Reduced Pressure Zone backflow preventer and according to the following diameter requirements:
|Diameter||Backflow Preventer Enclosure
Drain Capability (GPM)
|¼" to ½"||27 GPM|
|¾" to 1"||45 GPM|
|1 ¼" to 2"||155 GPM|
|2 ½" to 3"||260 GPM|
|4" and above||710 GPM|
4.0 Access for Testing and Maintenance
Equipment components such as test cocks and valve handles or hand wheels must be within 24 inches of the access opening.
Hinged access panels must be restrained in the open and closed position.
All unrestrained panels and horizontal hinged panels must weigh 70 lbs. or less.
5.0 Security and Vandalism
Access to the internal equipment shall be lockable. Access shall be by keyed devices or have the ability to affix padlocks
6.0 Materials of Construction
Exposed Exterior Wall Panel Materials