Kunkle 6254 Safety Valve — 4″ 250# Flange x 6″ 125# Flange, N Orifice (Steam ASME Section IV, Metal Seat)
SKU: KUN-6254-NM-G-FLG-4X6
The Kunkle 6254 is the ASME Section IV version of the 6252, certified for low pressure steam heating boilers. It is the same heavy-duty cast iron valve with a stainless steel semi-nozzle, trim and disc, dual control rings and a bolted bonnet — but it is built and stamped for a single set pressure of 15 PSI, which is not field adjustable. This 4″ 250# Flange x 6″ 125# Flange variant — N orifice, 4.774 in² — relieves 7486 lb/h of steam at that setting, carrying the ASME Section IV and XIII ‘HV’ stamp and National Board certification. Temperature range -20°F to 406°F. Per ASME, code valves with a cast iron A126 body may not be used in lethal or flammable service. If you need an adjustable set pressure, specify the 6252 instead.
Specifications
| Body Material | Cast Iron (A126 Cl. A or B) |
| Trim Material | Stainless Steel (SA351 CF8M semi-nozzle, 316 SS disc) |
| Inlet Size | 4" 250# Flange |
| Outlet Size | 6" 125# Flange |
| Outlet Configuration | Side outlet |
| Orifice Designation | N |
| Orifice Area | 4.774 in² |
| Set Pressure | 15 PSI (fixed) |
| Temperature Range | -20°F to 406°F |
| Capacity — Steam IV | 7486 lb/h |
| Service Media | Steam |
| ASME Certification | ASME Sections IV and XIII (HV stamp), National Board Certified |
| National Board Certified | Yes |
| Seat Type | Metal |
| Weight | 197 lb |
| Overall Height | 22-1/2 in |
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