RegO 3129G is one of the External Hydrostatic Relief Valves.
External Hydrostatic Relief Valves are designed especially for the protection of piping and shut-off valves where there is a possibility of trapping liquid LP-Gas or anhydrous ammonia. They may be installed in pipelines and hoses located between shut-off valves or in the side boss of RegO shut-off valves.
 
Specification:

• Part Number: RegO 3129G
• Start to discharge setting PSIG: 250
• Valve body material: Brass
• Spring: Stainless Steel
• Container connection M. NPT: 1/2”
• Height (Approx.): 2 19/32”
• Wrench Hex Section: 1 1/8”
• Protective Cap: 3129-40P
• Pipe-away/Adapter of Threads: 3129-10*
• Application: Commercial, Industrial
• Gases: LPG, Anhydrous Ammonia

Features:
- Relief valve designed to automatically reseat firmly after discharge.
- Resilient seat disc provides a “bubble-tight” seal.
- Available in both brass and stainless steel.
- Available in configurations that permit direct attachment of vent piping when required.