The Kunkle Figure 20 relief valve is an all bronze angle pattern liquid pressure relief valve with a pressure tight cap. The cap is removed to expose a drive screw and lock nut which is used to adjust the valve to the desired pressure setting.
(The Kunkle Figure 20 is neither UL Listed or FM approved and it is recommended that a Cla-Val 55L-60 be used for fire pump applications.)
3/4" MNPT x 3/4" FNPT