API 520 Bellow Balanced Safety Valve Manufacturer: API 520 Balanced Bellows Safety Valve with Flange, Inlet Class 900, Outlet Class 300 LB, 3 X 4 Inch. Specifications / Features The allowable tolerance of the seat pressure: ≤±3% of the set pressure Overpressure: ≤10% of the set pressure (gas) or ≤20% of the set pressure (liquid) Blowdown: ≤10% of the set pressure (gas) or ≤20% of the set pressure (liquid) Leakage: The valve seat has good tightness and the leakage rate conforms to API527. Bonnet: The bonnet of the safety valve is open, allowing the spring chamber to communicate with the atmosphere, which is beneficial to reduce the temperature of the spring, and is mainly suitable for containers of high temperature gas in which the medium is steam and does not pollute the atmosphere. Lever: The safety valve can be opened manually by the lever when the media pressure over 75% of the setting pressure (under the premise of ensuring safety). Design: ASME, API 526, API 520, ASME B 16.5 Material: ASTM A216 WCB Flange Pressure Grade: Inlet Class 900 LB & Outlet Class 300 LB Sizes range: Inlet 3 inches & Outlet 4 inches Inlet temperature range:  -29 ℃ ~ + 427 ℃ Test and Inspection: API 527