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Brand: GESTRA
GESTRA UNA 38 High-Pressure Ball Float Steam Trap PN 100
Description
A high-pressure ball float trap for superheated and saturated steam
The GESTRA UNA 38 is a ball float steam trap with a needle-valve control unit, built for high-pressure condensate duty in DN 15 to DN 50 (1/2 to 2 inch). The manufacturer states that it can be used under all operating conditions because it is unaffected by backpressure. Its 1.5415 (A182-F1) body and 1.7357 (A217-WC6) cover carry a PN 100 or Class 600 rating, and the data sheet also covers the UNA 39 for PN 160, Class 900 and Class 1500. That makes the UNA 38 a typical choice for power plant drains, high-pressure steam headers and process units where a small, light trap is not enough.
Technical specifications
| Parameter | Specification |
|---|---|
| Model | UNA 38, PN 100 / Class 600 (UNA 39 is the PN 160 / Class 900 / Class 1500 sibling) |
| Nominal size | DN 15, 20, 25, 40, 50 (NPS 1/2, 3/4, 1, 1 1/2, 2) |
| Body material | 1.5415 (A182-F1); optional 1.7335 (A182-F12) high-temperature version |
| Cover material | 1.7357 (A217-WC6); body gasket graphite/CrNi; internals stainless steel |
| End connections | Flange EN 1092-1 B2 PN 100; flange ASME B16.5 Class 600 RF; socket-weld DIN EN 12760 or ASME B16.11 Class 3000; butt-weld via transition pieces EN 12627 or ASME B16.25 |
| Pressure rating, PN 100 flange | 100 bar g at -10 to 20 °C; 85.7 bar g at 300 °C; 22.3 bar g at 530 °C |
| Orifices and max. differential pressure | Orifice 50 = 50 bar; orifice 64 = 64 bar; orifice 80 = 80 bar; orifice 80 MAX = 80 bar (large flow) |
| Hole diameter | 2.8 mm (O 50), 2.3 mm (O 64), 2.0 mm (O 80), 6.5 mm (O 80 MAX) |
| Control units | SIMPLEX (level-dependent float control, incl. hand vent valve) or DUPLEX (adds bimetallic air vent for saturated and superheated steam) |
| Overall length L | 300 mm (DN 15 to 25); 416 to 421 mm flanged DN 40 and 50 |
| Weight | 38 kg (DN 15 to 25 flanged) to 42 kg (DN 50 flanged); 35 kg weld ends |
| Optional extras | Manual float lifting lever; hand vent valve with DUPLEX control; 1.7335 material for higher temperature |
How the control unit works
As condensate enters the trap, the float lifts and moves a pilot valve. When more condensate leaves through the pilot valve than the balance opening admits, pressure in the control chamber drops, the bellows compresses and the main valve opens. A vent hole equalizes pressure between the control chamber and the trap so that the main valve closes again when the float falls. Because of this pilot principle, a single orifice size covers the full differential pressure range up to 80 bar. The DUPLEX version adds a thermostatic capsule that gives extra cold-water start-up capacity, listed from about 180 kg/h at 1 bar to about 2100 kg/h at 80 bar.
Selection and installation notes
Select the orifice from the real differential pressure and the hot-condensate capacity chart, and remember that the differential falls by 1 bar for every 7 m of lift downstream. The body can be repositioned to convert between horizontal (h) and vertical (v) flow to suit the pipework, and the flow direction is shown on the body as seen from the cover end. SIMPLEX suits cold condensate and superheated steam, while DUPLEX suits saturated steam where air must be vented. For lower pressures see the
, or browse steam trap products.Documents and quotation
The attached six-page GESTRA data sheet 818620 contains all rating curves, orifice data, dimensions and capacity charts. Send the steam pressure and temperature, back pressure, condensate rate, end connection standard and material requirements with your enquiry, and confirm the selected configuration against the current manufacturer documents before ordering.
Datasheets & Documents
- Datasheet GESTRA UNA 38, UNA 39 ball float steam trap data sheet 818620 Download
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About brand
Steam and condensate equipment has been GESTRA's field since 1902, when the company started in Bremen, Germany. Its steam traps, non-return valves and boiler control electronics are found in boiler houses worldwide. Seven Star LLC lists the GESTRA LRGT 16-1 conductivity transmitter, the NRGT 26-2 level transmitter and UNA series ball float steam traps, and supplies GESTRA boiler control parts, valves and steam trap spares to plants in Oman as an independent supplier.
GESTRA LRGT 16-1 and GESTRA boiler control
The LRGT 16-1 is a conductivity transmitter screwed into the boiler shell or blowdown line. It measures the electrical conductivity of the boiler water, which indicates the dissolved solids content, and sends a 4-20 mA signal to a conductivity controller that operates a continuous blowdown valve. The manufacturer also names condensate and feedwater monitoring as uses. The transmitter belongs with the GESTRA level electrodes, limiters and controllers fitted to steam boilers in the GCC, which is why searches for GESTRA boiler control and GESTRA boiler spare parts often end at this type of component.
Ordering GESTRA parts: what we need
Send the type designation and the data from the name plate: pressure rating, connection thread, measuring length, supply voltage and serial number. Tell us which controller and blowdown valve the transmitter works with, and the boiler pressure.
Browse GESTRA products by category: Liquid Analysis Sensors.
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Frequently Asked Questions
What pressure classes does the UNA 38 cover?
PN 100 and ASME Class 600 according to the data sheet; the sibling UNA 39 covers PN 160, Class 900 and Class 1500.
What is the maximum differential pressure of the UNA 38?
Up to 80 bar, depending on the orifice: 50, 64 or 80 bar (orifice 80 MAX also 80 bar).
Can the UNA 38 handle superheated steam?
The SIMPLEX control unit is described as suited to superheated steam, and the DUPLEX unit as suitable for saturated and superheated steam.
Which sizes are available?
DN 15, 20, 25, 40 and 50 (NPS 1/2 to 2).
Can the flow direction be changed?
Yes. The body and control unit can be repositioned to convert between horizontal and vertical versions.
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