51005001NT Pressure Limiting Valve
The Legom 51005001NT Pressure Limiting Valve (PLV) is a pressure control valve designed to reduce and regulate incoming water supply pressure to a safe level for downstream pipework and terminal equipment. When mains or district water supply pressure is too high for the user-side installation, installing a pressure limiting valve on the inlet pipeline protects downstream components — including underfloor heating pipes, fan coils, radiators, and other terminal equipment — from pressure-induced failure. The 51005001NT reduces an input pressure of up to 500 kPa to a regulated output pressure of 200 kPa, with a maximum working pressure of 1.6 MPa and a flow rate of 50 L/min at 350 kPa differential pressure.
Manufactured from DZR CZ132 dezincification-resistant brass with EPDM seals, the 51005001NT complies with AS1357.1 — the Australian standard for pressure limiting valves — and is rated for cold and hot water service. Its compact form factor with G1/2 threaded connections and Ø34mm body suits inline installation in domestic and commercial HVAC pipework.
Key Benefits
- Reduces 500 kPa input to 200 kPa output – Automatically reduces high mains or district supply pressure to a regulated 200 kPa downstream, protecting user-side pipework and terminal equipment rated for lower operating pressures
- Prevents pipeline burst from overpressure – Eliminates the risk of pressure-induced pipe failure in downstream components including underfloor heating pipes, plastic pipework, and terminal equipment with limited pressure ratings
- DZR CZ132 dezincification-resistant brass – The valve body material resists dezincification corrosion in potable water applications, maintaining structural integrity and leak resistance over the product’s service life in hard water and high-chloride environments
- EPDM seal material – Provides excellent resistance to hot and cold water, UV exposure, and a wide temperature range, ensuring long-term seal integrity without degradation from water chemistry variations
- AS1357.1 compliant – Certified to the Australian standard for pressure limiting valves, confirming the valve’s performance, materials, and construction meet the regulatory requirements for pressure control in water supply systems
- High flow capacity at 50 L/min – Delivers 50 L/min at 350 kPa differential pressure, supporting the flow demands of district heating systems, air handling units, fan coils, and radiator installations
- Max working pressure of 1.6 MPa – The valve body withstands working pressures up to 1.6 MPa, providing a wide safety margin above the 500 kPa rated input pressure
- G1/2 threaded connections – Standard threaded connections for straightforward installation into existing pipework without special fittings
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | 51005001NT |
| Valve Body Material | DZR CZ132 (dezincification-resistant brass) |
| Seal Material | EPDM |
| Medium | Water |
| Input Pressure | 500 kPa |
| Output Pressure | 200 kPa |
| Max Working Pressure | 1.6 MPa |
| Flow Rate | 50 L/min (at differential pressure = 350 kPa) |
| Connection | 2-G1/2-14 threaded |
| Body Diameter | Ø34mm |
| Standard | AS1357.1 |
Application & Use Cases
- District heating system connections – Installed at the point where district heating supply enters the user-side installation, reducing district network pressure to a safe level for the building’s internal heating distribution pipework and terminal equipment
- Underfloor heating systems with plastic pipework – PE-RT, PEX, and multi-layer composite pipes used in underfloor heating systems have lower pressure ratings than copper or steel. Installing a PLV at the cold water inlet protects this pipework from mains overpressure during both normal operation and pressure surges
- Air handling units and fan coils – Protects the coils and internal pipework of AHUs and fan coil units from overpressure damage when connected to high-pressure district or mains water circuits
- Radiator systems – Reduces inlet pressure to a level appropriate for radiator valve ratings and radiator body pressure limits in residential and commercial heating installations
- Domestic water supply systems with high mains pressure – In areas where mains water pressure regularly exceeds 500 kPa, a PLV protects all downstream domestic fittings, appliances, and pipework from the long-term damaging effects of sustained overpressure
- Commercial HVAC terminal equipment – Applied at the connection point of any terminal equipment with a lower maximum working pressure than the supply network, providing a regulatory pressure boundary between the supply and the equipment
Installation Notes
- Install a check ball valve upstream of the pressure limiting valve to facilitate maintenance and isolation without draining the entire supply system
- Ensure the direction of water flow matches the arrow marked on the product surface. Reverse installation will prevent the valve from functioning correctly and may damage the internal mechanism
- Before installing, flush the pipeline by passing water through to remove impurities, grit, and debris that could contaminate or damage the valve seat and internal components
- The valve should be installed on the cold water supply inlet before the user-side heating system, as shown in the installation diagram — with the PLV positioned downstream of the non-return isolating valve on the cold water line
- Use appropriate thread sealant or PTFE tape on the G1/2 threaded connections to ensure a leak-free joint
- After installation, check all connections for leaks and verify that downstream pressure readings are within the expected 200 kPa output range before commissioning the full system
Frequently Asked Questions
What is the difference between a pressure limiting valve and a pressure reducing valve?
The terms are often used interchangeably in practice. A pressure limiting valve (PLV) is specifically designed to limit downstream pressure to a set maximum — in this case 200 kPa — regardless of fluctuations in the upstream supply pressure. A pressure reducing valve (PRV) typically refers to the same type of device. Both function by automatically throttling flow to maintain a lower, regulated downstream pressure when the upstream pressure exceeds the valve’s setpoint. The 51005001NT is rated to AS1357.1, which is the Australian standard governing pressure limiting valves for water supply applications.
Why is DZR brass specified for the valve body?
Dezincification is a form of corrosion in which zinc is selectively leached from standard brass alloys in potable water, leaving a weak, porous copper structure that can fail under pressure. DZR (dezincification-resistant) brass alloys are formulated to resist this mechanism, maintaining structural integrity and pressure-bearing capacity over the valve’s service life — particularly in soft water, hard water, or water with elevated chloride content where standard brass would be vulnerable. CZ132 is the specific DZR brass grade used in the 51005001NT body.
Why is a check ball valve recommended upstream of the PLV?
A check ball valve upstream of the PLV allows the valve to be isolated from the supply without shutting off the entire building water supply. This is essential for maintenance — if the PLV needs to be inspected, cleaned, or replaced, the upstream isolation valve allows this work to be done without interrupting supply to the rest of the building. Without upstream isolation, any PLV maintenance requires a full supply shutdown.
Is the 51005001NT suitable for hot water as well as cold water?
The 51005001NT is rated for water service with EPDM seals, which are compatible with both hot and cold water across the normal temperature range of domestic and commercial HVAC systems. For confirmation of maximum operating temperature suitability for a specific hot water application, contact the Legom team with the system parameters.
What standard does the 51005001NT comply with?
The 51005001NT complies with AS1357.1 — the Australian standard for pressure limiting valves used in water supply systems. This standard covers performance requirements, materials, dimensions, and testing for PLVs intended to protect downstream plumbing from overpressure.
OEM & ODM Customization
Legom supports OEM and ODM services for the 51005001NT Pressure Limiting Valve. Our engineering team can customize pressure settings, connection sizes, and body materials to match specific system requirements. All customization projects are handled with strict confidentiality. Contact us via WhatsApp or info@legomsmart.com.
Datasheet
Product information last reviewed by the Legom Technical Team. For the most current specifications, refer to the official datasheet or contact our sales team.
Custom OEM & ODM Solutions
Legom is a direct manufacturer offering end-to-end OEM and ODM services. With our in-house engineering and production capabilities, we work closely with distributors and system integrators to deliver fully customized solutions under strict NDA.
