1/2" Brass Threaded Swing Check Valve (1101NL)

The 1101NL is a 1/2-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 1101NL completes the lead-free brass swing check valve series on Maxx-Supply — the smallest size in the line and the size that serves the terminal connection tier of every piping system where non-return protection is required at the individual fixture supply, instrument port, small equipment supply, and utility service connection level. One-half inch is the terminal pipe size across virtually every residential and commercial plumbing system — the size of the last supply connection before water reaches the fixture, appliance, or equipment it serves — and in systems where non-return protection is required at these terminal connections, the 1101NL is the correct lead-free brass swing check specification that serves that requirement.

The parallel between the 1101NL's position in the check valve series and the 982's position in the stainless threaded ball valve series is instructive. Just as the 982 at 1/2-inch completes the stainless ball valve series as the terminal connection isolation valve, the 1101NL completes the lead-free brass check valve series as the terminal connection non-return valve — the check valve that appears at the individual fixture supply, the individual equipment connection, the instrument port, and the terminal utility service outlet where piping systems of every type terminate their distribution at or near 1/2-inch nominal size. Every potable water system terminates in connections at or near 1/2-inch, and in systems where non-return protection is required at those terminal points, the 1101NL is the valve that serves every one of those locations.

Understanding where a 1/2-inch check valve appears requires understanding the specific non-return protection scenarios where check valves are specified at the terminal connection tier — scenarios where the small diameter and individual fixture scale of the 1/2-inch connection does not eliminate the need for non-return protection but rather defines the specific backflow risk that the check valve at that connection addresses. Individual fixture supply connections where cross-connection risk exists — hose bibb connections with submerged inlets, laboratory faucet connections with chemical contact risk, individual appliance supply connections where backpressure or backsiphonage could reverse flow into the potable supply — are the applications that generate 1/2-inch check valve specifications in residential and commercial potable water systems. The 1101NL serves these terminal connection non-return applications in the most compact lead-free brass swing check format in the series.

At 1/2 inches, the compact swing check body format of the 1101NL achieves the smallest physical footprint in the lead-free brass check valve series — fitting in under-sink supply connections, appliance supply line assemblies, fixture supply stub-out locations, and equipment utility access panels where the compact threaded body of a 1/2-inch check valve installs in the most confined installation spaces of any piping system application. The physical scale of the 1101NL is matched to the physical scale of the terminal connection applications it serves — a compact valve for compact connections, sized correctly for the individual fixture and equipment supply tier that 1/2-inch piping represents at the terminal point of every distribution system.

As the 1/2-inch counterpart to the 1102NL (3/4-inch), 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 1101NL completes the series from 1/2-inch through 2-inch — providing complete non-return protection coverage across the full residential and commercial check valve size range from the smallest terminal connection size to the primary supply main size, all in lead-free brass construction that meets federal potable water compliance requirements at every position in the distribution system.

The swing check valve design delivers the same automatic passive non-return protection at 1/2-inch that defines the 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 1/2 inches, the swing check mechanism is the correct non-return design for the terminal connection applications the 1101NL serves — the passive mechanical simplicity appropriate for the individual fixture supply and equipment connection non-return scenarios where the valve operates automatically and indefinitely without maintenance intervention across its full installation service life.

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 non-negotiable material compliance requirement that applies at the 1/2-inch terminal connection tier as completely and unambiguously as it does at the 2-inch primary supply main tier. Terminal connection check valves in potable water systems are wetted surface components subject to the full scope of lead-free compliance requirements regardless of their small size and individual connection scale, and the NL designation on the 1101NL confirms compliance at the terminal connection level where potable water contact is the defining service condition.

The threaded NPT end connections provide direct inline installation at the 1/2-inch fixture supply, appliance connection, and terminal service point locations where the 1101NL is most commonly specified — the most compact threaded connection format in the lead-free brass check valve series, appropriate for the confined installation spaces of under-sink supply assemblies, appliance supply connections, and individual fixture supply stub-outs.

Specifications

Industries & Applications

The 1101NL is the lead-free brass swing check valve specification for 1/2-inch non-return backflow prevention across the terminal connection, individual fixture supply, and small equipment connection applications where 1/2-inch is the working pipe size at the non-return location:

• Residential Hose Bibb & Outdoor Faucet Non-Return — Hose bibb and outdoor faucet connections are among the most common cross-connection risk points in residential plumbing — a garden hose left submerged in a bucket, pool, or chemical solution creates a backsiphonage pathway through the hose bibb connection if a supply pressure drop creates negative pressure at the fixture; a 1/2-inch check valve at the hose bibb supply connection prevents the backsiphonage backflow that this cross-connection scenario creates; the 1101NL lead-free NL construction meets the potable water material compliance requirements of residential plumbing permits at outdoor fixture supply connections where non-return protection is required by code or specified as a best practice.
• Residential Appliance & Individual Equipment Supply — Individual appliance supply connections — ice maker supply lines, dishwasher supply connections, refrigerator water supply, humidifier supply lines, and similar small appliance potable water connections — where 1/2-inch is the standard individual appliance supply line size and where non-return protection at the appliance supply connection prevents backflow from the appliance water circuit into the potable supply main under backpressure or backsiphonage conditions; the compact 1101NL format fits in the confined under-sink and behind-appliance installation spaces of residential appliance supply connections.
• Laboratory & Research Facility Faucet Connections — Individual laboratory faucet supply connections where cross-connection risk from chemical contact, specimen submersion, and laboratory procedure backpressure creates potable water contamination risk through individual fixture supply connections; 1/2-inch is the standard supply connection size for individual laboratory faucets and specialized laboratory fixture supply connections where non-return protection at the individual fixture level addresses the cross-connection risk of laboratory use conditions.
• Residential & Light Commercial Steam Radiator Connections — Individual steam radiator supply and condensate connection valves at 1/2-inch in residential and light commercial steam heating systems where the individual radiator supply connection size is 1/2-inch nominal; non-return protection at individual radiator supply connections in steam systems where condensate backflow through individual supply connections could affect system pressure balance and individual radiator performance; confirm temperature and pressure ratings against specific steam system conditions.
• Individual Fixture Non-Return — Healthcare & Institutional — Individual fixture supply non-return protection in healthcare facilities, dental offices, and institutional buildings where specific fixture types — dental unit water supply connections, medical equipment supply lines, and specialized institutional fixture supply connections — require non-return protection at the individual 1/2-inch fixture supply level to prevent backflow through individual fixture connections in healthcare and institutional plumbing systems with cross-connection risk at the fixture level.
• Light Commercial Equipment Supply — Individual Connection Non-Return — Individual small equipment supply connections in light commercial facilities where 1/2-inch is the supply connection size for specific commercial equipment — coffee machine supply lines, ice machine supply connections, individual beverage equipment supply branches, and other small commercial appliance supply connections — where non-return protection at the individual equipment supply connection prevents backflow through small equipment supply lines into the building potable water distribution system.
• Residential Irrigation — Zone Valve Supply Connections — Non-return protection at individual irrigation zone valve supply connections where 1/2-inch zone valve supply connections require check valve non-return protection at the zone valve supply inlet; the 1101NL provides compact lead-free non-return protection at individual zone valve supply locations in residential irrigation systems where zone valve manifold assembly space requires the most compact non-return valve format available.
• HVAC — Individual Instrument & Small Equipment Connections — Non-return protection at 1/2-inch individual HVAC instrument supply connections, condensate drain check applications, and small equipment supply non-return points in residential and light commercial HVAC systems where 1/2-inch is the connection size at individual instrument supply and small utility service connection points.
• Residential Well & Pump Systems — Small Capacity Applications — Non-return protection at 1/2-inch discharge connections on small capacity well pump systems, booster systems, and pressure systems where the pump discharge connection is 1/2-inch nominal; prevents back-spinning and reverse flow through small pump bodies when the pump cycles off on small residential water supply systems where the pump discharge connection size is 1/2-inch.
• Chemical Feed & Treatment — Small Injection Connections — Non-return protection at 1/2-inch chemical feed injection points, small dosing pump discharge connections, and chemical treatment system supply connections in residential and light commercial water treatment systems where the small scale of individual injection and dosing connections produces 1/2-inch check valve specifications at individual chemical feed points.