The Gestra BW31A is a return temperature control valve designed specifically for heating oil service. The valve features a high-quality carbon steel body, supports flanged or threaded connections, and offers pressure ratings up to PN40. Flow is controlled through the coordinated operation of the Thermovit temperature regulator and spring pressure. The valve automatically regulates the flow according to the configured closing temperature and is suitable for return temperature control and piping protection in industrial heating systems.
Gestra BW31A Return Temperature Control Valve product image
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BW31A Return Temperature Control Valve | Gestra
Return temperature control valve for heating oil, with a Thermovit regulator and spring pressure working together to control flow; flanged or threaded connections available.
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Specifications
- Media
- Heating oil
- Nominal size
- DN15, DN20, DN25, DN40
- Pressure rating
- DN15, DN20, DN25: PN40; DN40: PN25
- Maximum permissible differential pressure
- 6 bar (DN15, DN20, DN25)
- Closing temperature range
- DN15: 120–270 °C; DN20, DN25: 100–280 °C; DN40: 100–270 °C
- External adjustment closing temperature range
- DN15: 90–270 °C; DN20, DN25, DN40: 70–270 °C
- Special external adjustment closing temperature range
- DN15: 60–160 °C; DN20, DN25: 30–170 °C; DN40: 25–85 °C
- Connection type
- EN 1092-1 B1 flange, ASME B16.5 Class 150 RF flange, G-thread socket, NPT-thread socket
- Thread standard
- G thread: ISO 228-1; NPT thread: ASME B16.11
- Valve body material
- Steel, EN 1.0460 / ASTM SA 105
- Control principle
- Flow regulation by a Thermovit temperature regulator and spring pressure
- Installation position
- Installed in the return line; any orientation permitted. Horizontal piping with the bonnet facing upward or downward is recommended.
Application scenarios
Return temperature control in industrial heating systems
Installed in the return line of an industrial heating system, it controls the return temperature using a Thermovit temperature regulator.
Heating return temperature protection
As a temperature control component in the return line of a heating system, it regulates media flow according to the configured closing temperature to control the return temperature.
Installation & maintenance notes
Recommended horizontal piping and bonnet orientation
The BW31A should be installed in the return line and may be installed in any orientation. Horizontal piping is recommended, with the bonnet facing upward or downward.
Maximum permissible differential pressure of the control valve
During commissioning and operation of DN15, DN20, and DN25 models, the actual differential pressure across the valve should be kept within the maximum permissible differential pressure of 6 bar.
Verify the closing temperature range according to the model and adjustment configuration
Before commissioning, verify the closing temperature range according to the specific model and adjustment configuration to ensure that the target closing temperature is within the range specified for the applicable model and configuration.
FAQ
How does the BW31A return temperature control valve work?
The BW31A uses the Thermovit regulator to provide temperature-triggered flow control in the return circuit: when the return temperature falls, the regulator opens the flow orifice to increase the flow, and when the temperature rises, it restricts the flow. This keeps the return temperature stable relative to the set closing temperature. The closing temperature can be adjusted within the specified range after the valve leaves the factory.
What connection types are available for the BW31A?
The BW31A is available with EN/PN flanges, ASME flanges, threaded sockets, socket-weld ends and butt-weld ends, meeting on-site connection requirements to DIN, ANSI, ASME and other leading standards.
How do I select the BW31A model and size?
Model selection is based primarily on the DN size and the nominal pressure (PN). Common BW31A models include DN40 PN25, DN25 PN40, DN20 PN40 and DN15 PN40; the final choice depends on the actual pipe diameter, system pressure and medium conditions.
What are the main material specifications of the BW31A?
The valve body is steel (1.0460), the body bolts are A 193 B7, and the Thermovit regulator is stainless steel. The external adjustment device and the seals use the appropriate materials for the respective model range, and the remaining components are also selected to the corresponding EN/ASTM standards.
What should be considered when installing and maintaining the BW31A?
The valve should be installed in the return line, observing the flow direction arrow. Horizontal installation is ideal, with the bonnet facing up or down. If required, an external adjustment device can be fitted as an option, allowing the closing temperature to be adjusted during operation. For maintenance, refer to the relevant installation and operating instructions for on-site guidance.