SHUANGLIN VALVE | Brass Differential Pressure Control Valve, DN20–DN50

In HVAC systems with thermostatic radiator valves or modulating control valves, flow demand is constantly changing — and every time one zone closes down, the pressure available to every other zone shifts too. Left uncontrolled, this causes valve noise, uneven heating or cooling, and control valves that struggle to hold their position. SHUANGLIN VALVE's brass differential pressure control valve is designed specifically to absorb these swings, keeping the pressure across a branch circuit constant no matter how the rest of the system behaves.

How It Senses and Responds

Unlike a fixed-setting balancing valve, this valve reacts continuously. A capillary tube runs from the valve to a second point in the system — typically a partner balancing valve on the supply side, or a T-piece connection — carrying a live pressure signal back to an internal diaphragm. As system pressure rises, the diaphragm moves against a calibrated spring, gradually closing the valve to hold the differential pressure across the circuit at its set value. When pressure drops elsewhere in the system, the valve opens back up. The result is a self-correcting circuit that maintains stable conditions automatically, without any external power or control signal.

Designed to Work With Your Balancing Valve

This differential pressure control valve is commonly installed alongside a static balancing valve — the balancing valve sets the design flow rate for a circuit, while this valve holds the pressure conditions steady so that setting stays accurate even as other zones in the system open and close. If you're also sourcing SHUANGLIN VALVE's static balancing valve range, the two products are designed to complement each other in the same variable-flow system, with the capillary tube connecting directly to the partner valve's test port.

Build and Specification Highlights

The valve body is manufactured in solid brass, rated to PN16, with an EPDM diaphragm and stainless steel spring for long-term reliability under continuous cycling. It's supplied with a pre-fitted copper capillary tube for connection to the partner valve or system pipework, and is available in sizes from DN20 to DN50 with female threaded connections. The valve should be installed vertically in the return line of the controlled circuit, as marked by the flow direction arrow on the body.

Where It's Used

• Variable flow heating and chilled water systems with TRVs or modulating control valves

• Multi-zone commercial HVAC systems with fluctuating branch demand

• Retrofit projects where valve noise or hunting indicates unstable circuit pressure

• Systems using variable speed pumps, where overall system pressure changes with demand

Ordering Information

• Payment: T/T (Bank Transfer)

• Stock Items: Ships within 7 days

• Custom Orders: 30 days production time

• Logistics: Sea or air freight, with customs clearance assistance

Warranty & Customization

SHUANGLIN VALVE backs every differential pressure control valve with a 1-year warranty against manufacturing defects, including free repair or replacement where applicable. OEM/ODM services are available for custom pressure ranges, capillary tube lengths, and private-label packaging on bulk orders.

Frequently Asked Questions

Where does the capillary tube need to be connected? It connects to a second point in the system that provides the reference pressure signal — typically a partner balancing valve's test port on the supply side, or a T-piece in the pipework. The exact connection point depends on your system layout.

Does this valve need electricity or a control signal to operate? No. It operates entirely through the mechanical diaphragm-and-spring mechanism, responding directly to the pressure signal carried by the capillary tube.

Can this valve be used without a partner balancing valve? It's designed to pair with a balancing valve or a fixed reference point for best results, but the capillary tube can also be connected to a simple T-piece in some system configurations. Contact us to discuss your specific setup.

What sizes and pressure ranges are available? SHUANGLIN VALVE produces this differential pressure control valve from DN20 to DN50. Contact us with your required differential pressure range for a tailored recommendation.

Contact SHUANGLIN VALVE's sales team for a detailed quotation, technical drawings, or samples.