3/4" Brass Threaded Swing Check Valve (1102NL)

The 1102NL is a 3/4-inch lead-free brass threaded swing check valve engineered for automatic, non-return backflow prevention on water supply, steam, and compatible fluid service piping systems where preventing reverse flow at the check valve location is a system performance, equipment protection, or safety requirement — and where lead-free (NL) brass construction meets the potable water material compliance requirements of the federal Reduction of Lead in Drinking Water Act and the state and local plumbing codes that mandate lead-free wetted surface materials across all potable water system components.

The 3/4-inch diameter positions the 1102NL at the intersection of the highest-volume residential plumbing application tier and the dominant individual equipment supply and branch connection size in light commercial systems — a size that appears with greater frequency across the combined residential, light commercial, and small equipment connection application base than any other size in the lead-free brass swing check valve series. Three-quarter inch is the dominant residential supply branch size — the size of hot and cold water branches to individual fixtures across the residential water supply system, the standard connection size for residential water heaters, boilers, water softeners, and water treatment equipment, the supply line size for residential irrigation system connections, and the dominant individual equipment supply and branch connection size in light commercial mechanical systems where 3/4-inch branches serve individual fixtures, equipment connections, and terminal supply points throughout the building.

At the same time, 3/4-inch is the highest-frequency individual non-return valve location size in residential plumbing service work — the size at which check valves fail, are replaced, and are specified on the greatest number of individual residential and light commercial service calls. Residential water heater replacements, water softener installations, boiler makeup supply connections, residential irrigation system supply connections, and residential pump system discharge connections all generate 3/4-inch check valve specifications as routine elements of the service work scope. For residential plumbing service contractors, the 1102NL is the check valve that belongs on every service van in the same way that the 3/4-inch ball valve does — the size that a service plumber reaches for most frequently across the full range of residential and light commercial non-return valve specifications.

As the 3/4-inch counterpart to the 1B125CHECK-LF (1-inch), 1104NL (1-1/4-inch), 1105NL (1-1/2-inch), and 1106NL (2-inch) in the lead-free brass swing check valve series, the 1102NL serves the residential supply branch, individual equipment connection, and light commercial distribution tier of piping systems — the check valve position that is the most numerous per service call and the most frequently specified on residential plumbing and light commercial mechanical service work across the full range of non-return applications that service plumbers and light commercial mechanical contractors encounter in daily field work.

The swing check valve design delivers the same automatic passive non-return protection at 3/4 inches that defines the swing check mechanism across the full size series — a hinged clapper disc that opens under forward flow pressure and closes under gravity and reverse flow pressure without external power, control signals, or operator intervention. At 3/4-inch, the compact swing check body format is particularly well-matched to the under-sink, mechanical closet, equipment access panel, and residential utility room installation locations where 3/4-inch check valves are most commonly installed — locations where installation space is constrained and where the compact threaded body of the 1102NL fits without the footprint concerns that larger check valve formats present in tight residential and light commercial mechanical installation spaces.

The lead-free (NL) designation confirms compliance with the federal Reduction of Lead in Drinking Water Act's weighted average 0.25% lead limit on wetted surfaces — the material compliance requirement that applies across every check valve installation in the residential and light commercial potable water supply systems the 1102NL serves. For residential plumbing contractors who work across jurisdictions and encounter diverse local plumbing inspection requirements, the NL designation provides a single, nationally applicable lead-free compliance confirmation that eliminates the material verification questions that non-compliant check valve specifications generate during residential plumbing permit inspections.

The threaded NPT end connections provide direct inline installation with standard pipe thread sealant or PTFE tape in the residential supply branch piping, equipment connection nipples, and light commercial distribution branch fittings where 3/4-inch check valves are most commonly installed — no welding, no flange hardware, and no specialized installation tooling required for the full range of residential and light commercial service call check valve installation scenarios the 1102NL addresses.

Specifications

Industries & Applications

The 1102NL is the lead-free brass swing check valve specification for 3/4-inch non-return backflow prevention across the highest-frequency individual check valve size in residential plumbing and light commercial mechanical system applications:

• Residential Water Heater Supply Connection — Cold water supply check valve on residential tank and tankless water heater installations where thermal expansion in a closed system creates reverse pressure on the cold supply connection that requires check valve isolation of the heater from the supply main; three-quarter inch is the standard supply connection size on the vast majority of residential water heaters, making the 1102NL the standard check valve specification at the residential water heater supply connection — the single most common individual check valve installation location in residential plumbing service work; lead-free NL construction meets the potable water material compliance requirements of residential plumbing permits across all U.S. jurisdictions.
• Residential Boiler Makeup Water Supply — Cold water makeup supply check valve on residential hot water boilers and hydronic heating systems where a check valve on the 3/4-inch makeup water supply connection prevents backflow from the heating system loop into the potable cold water supply; residential boiler makeup water supply connections at 3/4-inch are among the most frequent individual check valve service call and replacement locations across residential mechanical service work, where check valve failure at the makeup supply connection allows heating system fluid to migrate back into the potable supply without the backflow protection the check valve provides.
• Residential Water Softener & Treatment Equipment — Inlet and outlet check valve connections on residential water softeners, iron filters, carbon filters, and water treatment system equipment where 3/4-inch inlet and outlet connections are the standard residential treatment equipment connection size; the 1102NL provides non-return protection at individual treatment equipment connections where check valves prevent backflow through treatment media and equipment components when supply pressure fluctuations reverse flow through the treatment train.
• Residential Irrigation System Supply — Non-return protection at the 3/4-inch residential irrigation system supply connection where preventing contaminated irrigation water backflow into the potable supply main is both a code requirement and a water quality requirement; three-quarter inch is the standard residential irrigation supply connection size where check valves provide non-return protection at the supply branch takeoff from the residential cold water main; confirm whether the 1102NL's swing check design meets applicable plumbing code backflow prevention device type requirements for the specific irrigation backflow prevention application.
• Residential Pump Systems — Pressure Tank & Jet Pump — Discharge non-return protection on 3/4-inch residential well pump, jet pump, and pressure booster system discharge connections where check valves prevent water hammer and back-spinning when the pump cycles off and prevent pressure tank water from flowing backward through the pump body during normal pressure cycling; three-quarter inch pump discharge connections are the standard size on residential jet pumps and small pressure booster systems where the 1102NL provides compact, lead-free non-return protection in the pressure tank connection assembly.
• Light Commercial Domestic Water — Individual Branch Supply — Individual branch supply check valve locations on light commercial domestic water systems in small office buildings, retail facilities, and light commercial buildings where 3/4-inch supply branches from 1-inch or 1-1/2-inch distribution mains serve individual restroom fixture groups, break room supply connections, and individual equipment supply branches; lead-free NL compliance meets potable water material requirements at the individual branch check valve positions of light commercial plumbing systems.
• HVAC Residential & Light Commercial — Hydronic Supply — Non-return protection at 3/4-inch zone supply connections, individual equipment supply branches, and circulation pump discharge connections on residential and light commercial HVAC hydronic heating and cooling systems where 3/4-inch is the dominant supply connection size at individual terminal equipment and zone distribution connections; prevents reverse flow through individual zone supply branches when zone pumps cycle off in variable flow and multi-zone hydronic systems.
• Residential & Light Commercial Steam Systems — Non-return protection at 3/4-inch steam supply branch connections and condensate return line connections in residential and light commercial steam heating systems where 3/4-inch steam supply and condensate connections to individual radiators, terminal heating units, and steam-heated equipment are the most numerous individual non-return locations in a typical residential or light commercial steam heating system; confirm temperature and pressure ratings against specific steam system conditions before specifying.
• Commercial Kitchen — Individual Equipment Supply — Non-return protection at 3/4-inch individual equipment supply connections on commercial kitchen equipment — individual pre-rinse spray supply connections, dishwasher cold water supply branches, and individual appliance supply shutoffs — where 3/4-inch is the dominant individual equipment supply connection size across commercial kitchen equipment and where lead-free NL compliance meets health department and commercial kitchen plumbing permit requirements at individual food service equipment supply connections.
• Multi-Family Residential — Individual Unit Supply — Non-return protection at 3/4-inch individual apartment unit supply connections, water heater supply branches, and individual unit isolation check valve locations in multi-family residential buildings where 3/4-inch is the standard individual unit supply branch size from the building distribution main; lead-free NL compliance meets residential building plumbing permit requirements at individual unit supply check valve positions across all U.S. jurisdictions.