Spirax Sarco USM21 is a sealed bimetallic thermostatic steam trap designed for installation with a pipe connector and compatible with various PC and IPC series connectors. It features a stainless steel body, a maximum operating pressure of 21 barg, and optional subcooling temperature settings of 10°C, 30°C, 50°C, or 70°C. It is suitable for condensate discharge from steam mains and steam tracing circuits on process lines.
USM21 sealed bimetallic steam trap real-life photo 2
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Spirax Sarco USM21 Sealed Bimetallic Steam Trap (Pipe Connector Mounted)
Stainless steel sealed bimetallic steam trap for steam mains and trace heating drainage, with selectable subcooling temperature.
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Specifications
- Steam Trap Type
- Sealed bimetallic thermostatic steam trap
- Maximum Allowable Pressure
- 50 barg at 40°C
- Maximum Allowable Temperature
- 450°C at 29 barg
- Minimum Allowable Temperature
- -29°C
- Maximum Operating Pressure
- 21 barg, for saturated steam
- Maximum Operating Temperature
- 400°C at 21 barg
- Minimum Operating Temperature
- 0°C
- Maximum Differential Pressure
- 21 barg
- Nominal Subcooling Temperature
- 10°C, 30°C, 50°C or 70°C below saturation temperature
- Corresponding Minimum Operating Differential Pressure
- 10°C subcooling: 5 bar g; 30°C subcooling: 2 bar g; 50°C subcooling: 0.5 bar g; 70°C subcooling: 0.1 bar g
- Body Material
- Stainless steel, ASTM A351 CF8
- Cover and Seat Material
- Stainless steel, AISI 316L
- Bimetallic Element Material
- Nickel alloy, G. Rau H46
- Connector Compatibility
- Can be installed on PC10, PC10HP, PC20, IPC20, IPC21, PC3 and PC4 pipe connectors
- Available Connection Types
- Threaded, socket weld, flanged
- Installation Orientation
- Can be installed in any orientation
- Available Certificate
- EN 10204 3.1.B
Application scenarios
Steam main drainage
Used for condensate drainage from steam mains. Product documentation explicitly states that this model can be used for main drainage, with a maximum operating pressure of 21 barg; it can be installed via a pipe connector and removed or replaced without disturbing the pipe connection.
Process line steam tracing drainage
Used for condensate drainage from process line steam tracing circuits. Product documentation explicitly states that this model can be used for steam tracing and offers rated subcooling temperature configurations of 10°C, 30°C, 50°C, or 70°C below saturation temperature; it can be installed in any orientation.
Selection points
Sealed Bimetallic Design
This product is a sealed bimetallic thermostatic steam trap, suitable for applications requiring a sealed steam trap.
Compatible with Pipe Connectors
Can be installed on PC10, PC10HP, PC20, IPC20, IPC21, PC3, and PC4 pipe connectors, allowing selection to match existing or specified compatible connector configurations.
Any Orientation Installation
The product can be installed in any orientation and is suitable for piping layouts with installation direction constraints.
Multiple Rated Subcooling Temperature Options
Rated subcooling temperature options of 10°C, 30°C, 50°C, or 70°C below saturation temperature are available. Different subcooling temperatures correspond to different minimum operating differential pressure requirements.
Stainless Steel Body and Cap Materials
The body is made of ASTM A351 CF8 stainless steel, and the cap is made of AISI 316L stainless steel, which can be used as selection criteria for body and cap material requirements.
Installation & maintenance notes
Use a Matching Pipe Connector
USM21 should be installed on compatible Spirax Sarco pipe connectors, including PC10, PC10HP, PC20, IPC20, IPC21, PC3, and PC4.
Verify Pressure and Temperature Operating Limits
Before commissioning, verify that the actual system pressure and temperature do not exceed the applicable range of USM21. The maximum operating pressure is 21 barg, and the maximum operating temperature is 400°C.
FAQ
What steam trapping applications is the USM21 suitable for?
The USM21 is suitable for steam tracing and steam main drainage. It is a sealed bimetallic thermostatic steam trap and can be installed in any orientation.
What are the maximum operating pressure and operating temperature of the USM21?
For saturated steam, the USM21 has a maximum operating pressure of 21 barg, a maximum operating temperature of 400°C at 21 barg, and a maximum differential pressure of 21 barg. The pressure and temperature limits of the complete assembly are also subject to the selected pipe connector and connection type.
Which pipe connectors can be used with the USM21?
The USM21 can be installed with PC10, PC10HP, PC20, IPC20, IPC21, PC3 and PC4 pipe connectors. Connectors are available in configurations including straight pattern, with Y-type strainer, with Spiratec sensor, or with piston valve. The specific configuration must be confirmed according to the actual model and application conditions.
What condensate subcooling options are available for the USM21?
The USM21 is available with nominal subcooling temperatures of 10°C, 30°C, 50°C or 70°C, discharging condensate at 10°C, 30°C, 50°C or 70°C below saturation temperature, respectively. Except during start-up and shutdown, the corresponding minimum operating differential pressures are 5 barg, 2 barg, 0.5 barg and 0.1 barg, respectively.
Does the USM21 require maintenance, and how is it replaced?
The USM21 is a sealed steam trap that requires no maintenance and has no internal spare parts. It is mounted to the pipe connector by two connector bolts. In the event of a fault, it can be removed and replaced from the connector without breaking the pipe connection.