Gestra UNA27 is a high-pressure float-and-ball steam trap with a rolling ball valve, available with Duplex dual-unit or Simplex single-unit control. The valve body is made of G20Mo5 and supports a maximum allowable working pressure of 63 bar g and a maximum temperature of 450°C. Nominal sizes range from DN25 to DN50, with flange, butt-weld, and socket-weld connection standards available. It is equipped with a check valve and drain plug, and is designed for high-volume condensate discharge in high-pressure steam systems and continuous drainage of high-temperature superheated steam lines.
Product photo of the Gestra UNA27 high-pressure steam trap, three-quarter view
1 / 1
UNA27 Ball Float Steam Trap | Gestra
Ball float steam trap with rolling ball valve, DN25 to DN50, rated up to 63 bar g and 450°C.
Genuine product assurance
We can help verify product data and purchasing details.
Model confirmation
Confirm model, connection and key options before ordering.
After-sales support
After-sales communication support is provided according to the order agreement.
Specifications
- Steam trap type
- Float-and-ball steam trap with rolling ball valve
- Control configuration
- Duplex dual control unit with a thermostatic bellows for automatic air venting, or Simplex single control unit without bellows
- Maximum allowable pressure/temperature
- 63 bar g at 250°C; 56 bar g at 300°C; 47 bar g at 400°C; 45 bar g at 450°C
- Maximum allowable temperature
- 450°C
- Maximum differential pressure
- 45 bar with the standard orifice; optional special orifices for 28 bar or 16 bar
- Nominal size
- DN 25, DN 40, DN 50
- Connection type
- DIN 2546 Type E PN 63 flanges; ASME B16.5 Class 300, Class 400/600 flanges; DIN 3239 Class 3000 socket-weld ends; DIN 3239 butt-weld ends
- Butt-weld end standard
- DIN 3239-2-R3, DIN 2559 Type 22 bevel
- Socket-weld end standard
- DIN 3239-R5 / ASME B16.11 Class 3000
- Valve body material
- G20Mo5 (1.5419), ASTM equivalent A217 WC1
- Valve seat material
- X8CrNiS18-9 (1.4305) / X80CrSiMoW15-2 (1.4732), ASTM equivalents AISI 303 / Stellite
- Float material
- X6CrNiMoTi17-12-2 (1.4571), ASTM equivalent A182 F316
- Bellows material
- X6CrNiTi18-10 (1.4541), ASTM equivalent A182 F321
- Flow coefficient KvS
- DN 25: 0.31 m3/h (0 45), 0.38 m3/h (0 28), 0.44 m3/h (0 16); DN 40/50: 1.1 m3/h (0 45), 1.5 m3/h (0 28), 2.1 m3/h (0 16)
- Orifice diameter
- DN 25: 3 mm (0 45), 3.5 mm (0 28), 4.1 mm (0 16); DN 40/50: 6.5 mm (0 45), 7 mm (0 28), 8.5 mm (0 16)
- Integrated features
- Equipped with a check valve and drain plug
- Optional configurations
- Float lifting lever; Duplex version available with a manual air vent valve
Application scenarios
Condensate discharge in high-pressure steam systems
For high-volume condensate discharge in steam systems and continuous drainage in high-temperature, high-pressure steam circuits.
Condensate discharge from superheated steam lines
For condensate discharge from high-temperature superheated steam lines.
Installation & maintenance notes
High-temperature and high-pressure operating condition checks
Before commissioning, verify that the operating pressure and temperature at the installation site do not exceed the allowable range specified for UNA27, preventing equipment damage or steam leakage caused by operation beyond the design conditions.
FAQ
Which steam system operating conditions is the Gestra UNA27 float-type steam trap suitable for?
The UNA27 is suitable for high-capacity condensate drainage in high-pressure steam systems and for continuous drainage of high-temperature superheated steam lines. When equipped with the Simplex single-control unit, it can discharge condensate or distillate, as well as condensate from superheated steam, gas, or compressed-air lines. Its maximum allowable temperature is 450°C. The maximum allowable pressure varies with temperature: 63 bar g at 250°C and 45 bar g at 450°C.
What is the difference between the Duplex dual-control unit and the Simplex single-control unit of the UNA27?
The Duplex dual-control unit is equipped with a thermostatic bellows for automatic air venting and is suitable for condensate drainage applications requiring automatic air removal. The Simplex single-control unit does not have a bellows and can be used to discharge condensate, distillate, and condensate from superheated steam, gas, or compressed-air lines. The Duplex version can also be optionally equipped with a manual air vent valve.
How should the nominal size and orifice differential-pressure rating be selected for the Gestra UNA27?
Selection should be based on the inlet pressure, outlet pressure, condensate flow rate, installation position, and operating conditions. The UNA27 is available in DN25, DN40, and DN50 sizes. The standard orifice has a maximum differential pressure of 45 bar; special orifices with maximum differential pressures of 28 bar or 16 bar are also available to provide higher flow capacity. For DN25, the KvS values with 45 bar, 28 bar, and 16 bar orifices are 0.31, 0.38, and 0.44 m³/h, respectively. For DN40 and DN50, the corresponding values are 1.1, 1.5, and 2.1 m³/h.
How does condensate lift downstream of the UNA27 affect the available differential pressure?
When condensate must be lifted downstream of the steam trap, the lifting height consumes available differential pressure. The available differential pressure decreases by approximately 1 bar for every 7 m of condensate lift. Therefore, the downstream lifting height and the pressure difference between the inlet and outlet should both be included in the calculation when selecting the orifice, valve size, and discharge capacity.
What connection options are available for the Gestra UNA27, and must the pipeline be removed for maintenance?
The UNA27 is available with DIN 2546 E-type PN63 flanges, ASME B16.5 Class 300 and Class 400/600 flanges, DIN 3239 Class 3000 socket-weld ends, and DIN 3239 butt-weld ends. Nominal sizes are DN25, DN40, and DN50. The valve body has a bolted bonnet, and the control unit can be replaced without removing the steam trap from the pipeline. The valve is also equipped with a check valve and a drain plug.