PN16
Product Overview
Spirax Sarco MST21/MST21H is a repairable pressure balanced thermostatic steam trap made entirely of stainless steel, providing excellent corrosion resistance. This product is designed specifically for relatively small condensate discharge applications, especially suitable for trace heating line applications. Different discharge temperature bellows can be selected according to actual requirements to meet diverse operating condition needs. The product fully complies with the European Pressure Equipment Directive 97/23/EC, with reliable quality and test reports available (must be specified when ordering).
Core Parameters and Models
Model Classification
The product includes two core models, designed for different capacity requirements, with specific specifications as follows:
- MST21: Standard capacity model, suitable for conventional trace heating line scenarios, supporting ¼", 3/8", ½" size options
- MST21H: High capacity model, designed for special application scenarios, supporting ½", ¾", 1" size options
Bellows Specifications
The bellows determine the condensate discharge temperature and must be clearly specified when ordering:
- STD type: Discharges condensate approximately 10℃ below saturated steam temperature
- SUB type: Discharges condensate approximately 22℃ below saturated steam temperature
- NTS type: Discharges condensate approximately 4℃ below saturated steam temperature
Dimensions and Weight
| Size | A(mm) | B(mm) | C(mm) | D(mm) | Weight(kg) |
|---|---|---|---|---|---|
| ¼" | 50.5 | 8.5 | 10 | 45 | 0.34 |
| ½" | 61.0 | 12.5 | 14 | 45 | 0.48 |
| 3/8" | 68.0 | 14.0 | 14 | 45 | 0.48 |
| ¾" | 68.0 | 14.0 | 14 | 45 | 0.48 |
| 1" | 75.0 | 14.0 | 14 | 45 | 0.48 |
Component Material Details
| No. | Component | Material Standard |
|---|---|---|
| 1 | Body | ASTM A743 CF16Fa |
| 2 | Cover | 420A UGIMA AISI 420 |
| 3 | Bellows | Stainless steel (no specific standard number) |
| 4 | Spring | BS 2056 302 S26 |
| 5 | Partition plate | BS 1449 304 S15 |
| 6 | Strainer (0.8mm aperture) | ASTM A240 316L |
| 7 | Gasket | BS 1449 304S15 |
Installation and Maintenance
Installation Requirements
- Install vertically, ensuring the bellows is horizontal with the inlet at the top; if horizontal installation is required, it is recommended to install a drop leg in advance
- Suitable isolation valves should be installed before and after the steam trap to ensure safety during maintenance or replacement
- Remove packaging before installation, slowly open the isolation valve until the system operates stably, and check for any leaks
- The body/cover gasket includes a stainless steel support ring, handle with care when removing or installing
Recommended Tightening Torque
| Component Assembly | Size | Specification | Tightening Torque(N·m) |
|---|---|---|---|
| Body and Cover | ¼" | 22A/F | 100-110 |
| Body and Cover | ½" | 32A/F | 100-110 |
| Body and Cover | 3/8" | 32A/F | 100-110 |
| Body and Cover | ¾" | 36A/F | 100-110 |
| Body and Cover | 1" | 41A/F | 100-110 |
Safety and Maintenance
For detailed installation and maintenance guidelines, please refer to the IM-P125-07 document provided with the product. The product can be recycled and will not cause ecological problems.
Spare Parts Information
Available Spare Parts List
| Applicable Product | Available Spare Part No. |
|---|---|
| MST21 | 3 (Bellows), 4 (Spring), 5 (Partition plate), 6 (Strainer), 7 (Gasket) |
Spare Parts Ordering Instructions
When ordering spare parts, the following information must be clearly specified: steam trap size, product model, bellows type. Example: 1-internal parts, for ¼" MST21 steam trap, 'STD' type bellows, discharges condensate approximately 10℃ below saturated steam temperature.
Ordering Instructions
When ordering, product specifications must be detailed. Example: 1-Spirax Sarco ½" MST21 pressure balanced steam trap, NPT threaded connection, 'STD' type bellows (discharges condensate approximately 10℃ below saturated steam temperature). If a product test certificate is required, it must be specifically noted when ordering.
