Three Models Available (General/Steam/Liquid-Filled)
Product Overview
Spirax Sarco SG253 Sight Glass is a ductile iron double window sight glass with flanged connection, compliant with European Pressure Equipment Directive 97/23/EC, stamping available upon request. Test reports can be provided, if EN 10204 3.1 certificate is required, it must be clearly specified when ordering. This product is suitable for steam systems and other applications, the double window design allows easy observation of internal media conditions, the body is made of high-strength ductile iron material, ensuring structural stability and service life in high temperature and pressure environments.
Technical Specifications
Pressure/Temperature Limits
PN25 Flange Standard
| Parameter | Value |
|---|---|
| Max. Allowable Pressure (PMA) | 25 bar g @ 100°C |
| Max. Allowable Temperature (TMA) | 280°C @ 18 bar g |
| Max. Working Pressure on Saturated Steam (PMO) | 21 bar g |
| Max. Working Temperature (TMO) | 280°C |
| Design Max. Cold Hydraulic Test Pressure | 38 bar g |
| Max. Test Pressure (Steam, PTMX) | 21 bar g |
ANSI 150 Flange Standard
| Parameter | Value |
|---|---|
| Max. Allowable Pressure (PMA) | 17.2 bar g @ 35°C |
| Max. Allowable Temperature (TMA) | 280°C @ 10 bar g |
| Max. Working Pressure on Saturated Steam (PMO) | 13.8 bar g |
| Max. Working Temperature (TMO) | 280°C |
| Design Max. Cold Hydraulic Test Pressure | 30 bar g |
| Max. Test Pressure (Steam, PTMX) | 13.8 bar g |
General Parameters
| Parameter | Value | Notes |
|---|---|---|
| Min. Allowable Temperature | -10°C | - |
| Min. Working Temperature | 0°C | Consult Spirax Sarco below this temperature |
Sizes and Pipe Connections
- Available Sizes: DN15, DN20, DN25, DN32, DN40, DN50
- Flange Standards: EN 1092 PN25, BS 1560 (ANSI) Class 150
Product Structure
Materials of Construction
| No. | Part Name | Material Specification |
|---|---|---|
| 1 | Body | Ductile Iron DIN 1693 GGG 40.3 |
| 2 | Cover | Ductile Iron DIN 1693 GGG 40.3 |
| 3 | Window | Borosilicate Glass DIN 7080 |
| 4 | Gasket | Reinforced Graphite Sheet |
| 5 | Cover Bolts | Steel BS 3692 Gr. 8.8 |
Dimensions and Weights
Dimensions/Weights (Approximate)
| Size | A-PN25 | A-ANSI150 | B | E | F | Weight |
|---|---|---|---|---|---|---|
| DN15 | 130 | 126 | 55 | 45 | 10 | 3.2 kg |
| DN20 | 150 | 142 | 55 | 45 | 10 | 4.1 kg |
| DN25 | 160 | 152 | 70 | 63 | 15 | 5.0 kg |
| DN32 | 180 | 175 | 70 | 63 | 15 | 5.9 kg |
| DN40 | 200 | 199 | 90 | 80 | 20 | 9.1 kg |
| DN50 | 230 | 228 | 90 | 80 | 20 | 10.9 kg |
Note
Dimensions in mm, weights are approximate values.
Safety Information
Warning
- Condensate in certain applications (especially containing corrosive alkaline or acidic substances) can dissolve the window glass, regular inspection of window glass is recommended, replace immediately if thinning is observed
- Safety glasses must be worn to protect eyes when observing through the window
- Protective measures should be taken to prevent injury to personnel and equipment from broken glass in case of sight glass failure
Installation and Maintenance
Installation Requirements
- Isolation valves must be installed before and after the sight glass, upstream isolation valve should be closed first to prevent pressure overload
- Can be installed horizontally or vertically downstream of steam traps; if installed after blast discharge traps (such as thermodynamic traps), maintain at least 1 meter distance to avoid thermal and pressure shock to window glass
- Adequate maintenance space must be provided during installation
Recommended Tightening Torques
| Part | Size Range | Quantity | Specification | Tightening Torque (Nm) |
|---|---|---|---|---|
| Cover Bolts (No. 5) | DN15 - DN20 | 8 | 17 A/F, M10 × 30 | 12 |
| Cover Bolts (No. 5) | DN25 - DN32 | 8 | 17 A/F, M10 × 40 | 28 |
| Cover Bolts (No. 5) | DN40 - DN50 | 8 | 19 A/F, M12 × 40 | 38 |
Maintenance Instructions
For detailed maintenance procedures, refer to the Installation and Maintenance Instructions (IM-S32-04) provided with the product.
Spare Parts
Available Spare Parts
| Spare Part Name | Part No. |
|---|---|
| Window and Gasket Set | 3, 4 |
| Gasket Set | 4 |
Note
Cover bolts (Part 5) are not available as spare parts.
Ordering Information
Ordering Example
1-Spirax Sarco DN20 SG253 Sight Glass, Ductile Iron Body, EN1092 PN25 Flanged Connection
Spare Parts Ordering Instructions
- When ordering spare parts, specify the sight glass model and size, and order using the spare part names listed above
- Spare parts ordering example: 1-Window and Gasket Set for SG253 Sight Glass
Disposal and Environment
This product can be recycled. Disposal according to standard procedures will not cause environmental problems.
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