Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number NI 13.1-1.50 DN40STRAIGHT 50PSI found under Valve Safety Relief by Monarch Supply Company Inc. The National Stock Number assigned to this part is 4820016544055, and the Federal Supply Class is 4820 Valves Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like NI 13.1-1.50 DN40STRAIGHT 50PSI.