Spill-Resistant Vacuum Breaker (SVB)
The indoor-appropriate pressure vacuum breaker. Provides the same back-siphonage protection as a PVB but without the water discharge from the air inlet — suitable for laboratory faucets, indoor hose connections, and applications where spillage is unacceptable.
Technical Specification
- CSA Standard
CSA B64.1.3— Spill-Resistant Pressure Vacuum Breakers- Also listed as
- ASSE 1056 (US)
- Protection Type
- Back-siphonage only (not suitable for backpressure protection)
- Key Difference from PVB
- Air inlet designed to minimize spillage during pressure cycling; suitable for indoor use
- Hazard Classification
- Minor hazard connections
- Testing Frequency
- Annual
- Installation Requirement
- Must be installed above the highest downstream outlet; no below-grade installation
CSA B64.1.3 — Canadian Standards Association; ASSE 1056 — American Society of Sanitary Engineering
SVB vs. PVB
The standard PVB (CSA B64.1.2) discharges a small amount of water from the air inlet each time the supply pressure cycles — this is normal operation and is acceptable for outdoor applications where the water can drain to grade. In indoor environments, this spillage creates water damage, mold risk, and maintenance issues.
The SVB resolves this by incorporating a modified air inlet assembly that contains the water discharge, making it suitable for indoor laboratory faucets, indoor hose bibb connections, and utility sinks in buildings where the PVB's normal discharge is not acceptable.
Both assemblies protect against back-siphonage only. Neither can protect against backpressure conditions.
Typical Applications
- Laboratory faucets — Indoor lab water connections in research facilities, hospitals, and university campuses
- Indoor hose bibb connections — Commercial utility rooms, janitor rooms, indoor wash-down stations
- Process equipment connections — Low-hazard equipment in food service or manufacturing with indoor water supply connections
- Dental unit water lines — Some configurations (note: many water authorities require RPZ for dental; verify with your authority)
Annual Testing
Like all approved backflow prevention assemblies, SVBs require annual field testing by a certified tester. The test verifies that the check valve holds and that the air inlet valve opens at the correct vacuum threshold. Test results are submitted to the governing water authority.
Frequently Asked Questions — SVB
Can an SVB replace an RPZ in a laboratory?
No. Severe-hazard laboratory connections require an RPZ assembly. The SVB is suitable only for minor-hazard connections in indoor environments. If a laboratory connection has chemical or biological contamination potential, the water authority will require an RPZ. An SVB cannot be substituted for an RPZ regardless of the installation location.
Does an SVB need to be winterized like a PVB?
SVBs installed in heated indoor environments do not require seasonal winterization. SVBs in unheated areas or outdoor enclosures should be drained before freezing temperatures, as with all vacuum breaker assemblies.
Is annual testing required for SVB assemblies?
Yes. All approved backflow prevention assemblies — including SVBs — are subject to annual testing requirements under municipal water authority bylaws. The testing procedure for an SVB is similar to that for a PVB and requires a calibrated vacuum test gauge.
Need your backflow assemblies tested?
We test all CSA B64-listed assemblies across Canada.