Brass Differential Pressure Bypass Valve (DPBV)
The Brass Differential Pressure Bypass Valve (DPBV) is a sophisticated, non-electric control valve designed to stabilize hydraulic systems, particularly in HVAC applications like chilled water and heat pump systems. By diverting flow based on pressure differential, the DPBV ensures stable operation of the main plant (e.g., heat pumps) while allowing the user-side (terminal units) to operate on variable flow.
📋 Key Product Features
| Parameter | Detail |
| Material | Brass |
| Function | Automatic Pressure Differential Stabilization and Bypass |
| Adjustable Range | 0.5 – 3Bar and 0.2 – 1Bar (Two common ranges to meet different system needs) |
| Design | Visual Adjustment Function for simple, intuitive operation. |
| Application | Broad applicability in both Residential and Commercial water systems. |
💡 Working Principle (The “Smart Valve”)
The DPBV acts as a “smart valve” by sensing the pressure difference between the supply and return lines of the main circuit:
Sensing: The valve constantly monitors the pressure differential (∆P) between the two connection points.
Modulation: When the sensed pressure differential (∆P) reaches a pre-set value, the valve opens proportionally.
Stabilization: The opening action allows a specific volume of fluid to bypass directly from the supply to the return line. This bypass flow ensures the ∆P across the valve connections is always maintained at the set system value.
Shut-off: If the pressure differential falls below the set value, the valve closes, stopping the bypass flow.
🏢 System Application: Constant vs. Variable Flow
The DPBV is a crucial component for optimizing energy efficiency and control in large water systems:
| System Side | Requirement | Function of DPBV |
| Primary (Chiller/Heat Pump) | Constant Flow (Fixed Volume System) is required to guarantee stable, efficient operation of the main unit (e.g., Air Source Heat Pump). | Maintains a constant pressure differential across the main header, which guarantees a constant flow rate through the primary equipment (the heat pump unit). |
| Secondary (Terminal Units/Coils) | Variable Flow System is desired to reduce pump energy consumption and allow energy transfer between terminal units based on load. | Absorbs the excess flow (when terminal valves close) and routes it to the return line, balancing the variable demands of the secondary side with the fixed flow needs of the primary side. |
This control method reduces running costs (lower pump energy) and system installation costs while ensuring precise temperature control at the terminals.
🔧 Key Usage and Installation Points
Installation Location:
The DPBV can be installed across the main system supply and return lines.
Alternatively, a single DPBV can be installed at the farthest terminal unit in the system, which often provides the most accurate location for pressure sensing.
Terminal Control: When using a DPBV control system, the terminal fan coil units (or similar devices) must be regulated using Electric 3-Way Valves (not 2-way valves).
System Protection: A Buffer Tank (Storage Water Tank) must be employed to prevent the main unit’s compressor from cycling frequently, which protects the unit and saves energy.
Commissioning Steps:
During system commissioning, the main circuit valve should be closed to simulate a scenario where all terminal units are closed (maximum ∆P).
The DPBV should then be adjusted to ensure the flow through the main unit (e.g., heat pump) remains stable at the required rate.
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