The Spirax Sarco S and SF series are cast iron inverted bucket steam traps with integral strainers, available with BSP threaded or PN16 flanged connections. The body is manufactured from GG25 cast iron, with a maximum operating pressure of 13 barg and a maximum operating temperature of 300°C. Versions are available with maximum differential pressures of 4, 8, and 12 bar. Suitable for condensate drainage from low points in steam mains, pipeline ends, and steam-heated equipment.
Spirax Sarco cast iron inverted bucket steam trap SA8 product front view
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S/SF Cast Iron Inverted Bucket Steam Traps | Spirax Sarco
Cast iron inverted bucket steam traps with integral strainers, available with threaded or flanged connections.
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Specifications
- Operating principle
- Inverted bucket steam trap
- Body material
- Cast iron, DIN 1691 GG25
- Key internal component materials
- Stainless steel. Main component materials include X30 Cr 13, BS 1449 304, and ASTM A240 316L
- Connection type
- Threaded or flanged connections, both with integral strainers
- Thread standard
- BSP, BS EN10226
- Flange standard
- EN 1092 PN16, compatible with UNI 2237 / 2229
- Connection sizes
- Threaded: 1/2, 3/4, 1, 1 1/2; flanged: DN15, DN20, DN25, DN40
- Body design pressure
- PN16
- Maximum allowable pressure
- 16 barg @ 120°C
- Maximum allowable temperature
- 300°C @ 9.6 barg
- Minimum allowable temperature
- -10°C
- Maximum operating pressure
- 13 barg @ 195°C, for saturated steam
- Maximum operating temperature
- 300°C @ 9.6 barg
- Minimum operating temperature
- 0°C
- Maximum differential pressure ratings
- 4 bar, 8 bar, 12 bar, configured by specification
- Cold hydraulic test pressure
- 24 barg
- Installation orientation
- Install the trap body vertically with the strainer cap at the bottom
- Applicable Pressure Equipment Directive
- European Pressure Equipment Directive 97/23/EC
- Available certification
- EN10204 3.1.B
Application scenarios
Steam main drainage at low points and line ends
Installed at collection points or line ends on steam mains to discharge condensate formed during steam distribution. This series uses inverted bucket steam traps for saturated steam service and is available with integral strainers and threaded or flanged connections.
Condensate discharge from steam-heated process equipment
Installed at condensate outlets of steam-heated equipment to discharge condensate generated during operation. This series uses inverted bucket steam traps, is available with threaded or flanged connections, and features a maintainable design.
Selection points
Built-in filter for both threaded and flanged connections
The product is available with threaded or flanged connections, and both connection types include a built-in filter.
Select the 4 bar, 8 bar or 12 bar rating according to the actual differential pressure
The product can be configured with maximum differential pressure ratings of 4 bar, 8 bar or 12 bar. Select the appropriate rating based on the actual differential pressure.
Stainless steel critical internal components
Critical internal components are made of stainless steel. The primary materials include X30 Cr 13, BS 1449 304 and ASTM A240 316L.
Install the valve body vertically with the filter cover at the bottom
The valve body must be installed vertically, with the filter cover positioned at the bottom.
Cast iron valve body and pressure-temperature limits
The valve body is made of DIN 1691 GG25 cast iron. The maximum allowable pressure is 16 barg at 120°C, the maximum operating pressure for saturated steam is 13 barg at 195°C, and the corresponding pressure at 300°C is 9.6 barg.
Installation & maintenance notes
Install the body vertically with the strainer cap facing downward
Install the body vertically with the strainer cap at the bottom to ensure vertical movement of the bucket.
Verify operating conditions and differential pressure rating
Before installation, verify that the actual pressure, temperature, and differential pressure match the selected specification. Do not exceed the permitted operating limits or the applicable maximum differential pressure rating, 4 / 8 / 12 bar.
Refer to the installation and maintenance guide
For safety information and installation and maintenance details, refer to installation and maintenance guide IM-P077-02 supplied with the product. Capacity chart TI-P077-03 is also provided on the product page for selection reference.
FAQ
What is the operating principle of S and SF Series inverted bucket steam traps?
The S and SF Series feature cast iron bodies and integral strainers. Steam trapping and discharge are achieved through the vertical movement of the bucket. The mechanism is that water droplets entering the strainer are retained, while the valve remains open when steam passes through and moisture is discharged.
What is the main difference between the S and SF Series connection types?
The S Series has threaded connections with integral strainers, and models such as SB and SA are suitable for threaded connections. The SF Series has flanged connections with integral strainers, with DN sizes corresponding to flanged connection specifications. Refer to the product page table for specific model comparisons.
What pressure and temperature limits should be considered for this product?
The body design rating is PN16. Maximum allowable pressure is 16 barg at 120°C, and maximum operating pressure is 13 barg at 195°C for saturated steam, or under saturated steam conditions at the corresponding temperature. The minimum operating temperature is 0°C and the minimum allowable temperature is -10°C.
What certifications and certificates are available for this series?
The product complies with European Pressure Equipment Directive 97/23/EC, and an EN10204 3.1.B certificate is available upon request at the time of order.
How do I determine the appropriate size and flange standard model?
Sizes and connection types are distributed by model: SA, SB, SC, and SD use threaded connections, while SFA, SFB, SFC, and SFD use flanged connections. Available sizes include DN15, DN20, DN25, and DN40. Specific selection should consider actual operating conditions and piping connection standards.