LESER Type 811/821 Safety Relief Valve
Product Overview
The LESER Type 811/821 Pilot-Operated Safety Relief Valves are designed for precision pressure relief and environmental safety in high-pressure industrial systems. The Type 811 features pop action for rapid gas relief, while the Type 821’s modulate action ensures proportional opening, reducing emissions and noise for vapor, gas, and liquid applications. Fully compliant with API 526, these valves offer exceptional tightness up to 97% of set pressure and operate reliably up to 426 bar. Their robust design and integrated backflow preventer make them ideal for critical applications in petrochemicals, energy, and LNG/LPG industries, prioritizing both safety and environmental responsibility.
Key Features
- Precision Control: Type 811 (Pop Action) for rapid gas relief, Type 821 (Modulate Action) for proportional opening with reduced emissions.
- Environmental Safety: Non-flowing pilot design minimizes media loss and emissions.
- API 526 Compliance: Ensures seamless integration with industry-standard systems.
- High Tightness: Maintains tightness up to 97% of set pressure for enhanced safety.
- Robust Back Pressure Capability: Handles back pressures up to 70% of set pressure.
- Durable Materials: Constructed with SA 216 WCB, SA 351 CF8M, and optional Monel or Hastelloy.
- Integrated Safety Features: Backflow preventer and supplementary loading system for operational reliability.
- Low Maintenance: Designed for extended valve life with minimal media flow through the pilot.
Technical Specifications
| Parameter |
Type 811 (Pop Action) |
Type 821 (Modulate Action) |
| Set Pressure (CE) |
2.5–256 bar (36–3705 psig) |
1–426 bar (15–6179 psig) |
| Set Pressure (ASME) |
2.5–256 bar (36–3705 psig) |
1–689 bar (15–10000 psig) |
| Temperature Range (CE) |
-45°C to 200°C (-49°F to 392°F), Special: -162°C to 300°C |
-45°C to 200°C (-49°F to 392°F), Special: -162°C to 300°C |
| Temperature Range (ASME) |
-49°F to 392°F, Special: -259.6°F to 572°F |
-49°F to 392°F, Special: -259.6°F to 572°F |
| Nominal Diameter at Inlet |
DN 25–DN 200 (NPS 1–NPS 8) |
DN 25–DN 200 (NPS 1–NPS 8) |
| Actual Orifice Diameter (d₀) |
11–180 mm (0.433–7.087 in) |
11–180 mm (0.433–7.087 in) |
| Actual Orifice Area (A₀) |
95–25446.9 mm² (0.147–39.443 in²) |
95–25446.9 mm² (0.147–39.443 in²) |
| Flange Rating Inlet |
PN 10–PN 250, ASME Class 150–1500 |
PN 10–PN 400, ASME Class 150–2500 |
| Body Material |
1.0619, 1.4408, SA 216 WCB, SA 351 CF8M, SA 352 LCB, SA 494 M35-1 (Monel), SA 494 CX2MW (Hastelloy) |
1.0619, 1.4408, SA 216 WCB, SA 351 CF8M, SA 352 LCB, SA 494 M35-1 (Monel), SA 494 CX2MW (Hastelloy) |
| Seat Gasket |
Soft sealing, metallic, sealing plate |
Soft sealing, metallic, sealing plate |
| Load Type |
Medium-controlled |
Medium-controlled |
Applications
The LESER Type 811/821 valves excel in precision pressure relief for critical industries:
- Petrochemicals: Ensures safe pressure control in refining and chemical processing.
- Energy Sector: Protects steam and gas systems in power generation.
- LNG and LPG: Manages high-pressure relief in liquefied gas systems.
- Technical Gases: Provides reliable relief for compressed gas applications.
- Oil and Gas: Safeguards pipelines and production facilities.
Frequently Asked Questions
How does the Type 821 reduce emissions?
Its modulate action opens proportionally to overpressure, minimizing product loss and emissions.
Are these valves suitable for high-pressure systems?
Yes, they handle pressures up to 426 bar (6179 psig) for Type 821 and 256 bar (3705 psig) for Type 811.
What is the benefit of the backflow preventer?
It enhances safety by preventing reverse flow, integrated as a standard component.
Can these valves be tested during operation?
Yes, the supplementary loading system allows function testing and adjustment without downtime.
What materials are available for harsh environments?
Options include Monel and Hastelloy for corrosion-resistant applications.
Contact Us
For more information about the LESER Type 811/821 Safety Relief Valves, pricing, or to request a demo, contact our team:
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