That’s a *SS Model S10 safety relief valve, 3/4" size*.
On the red label you can see *S.P. 10 kg/cm2* — that’s the set pressure.
*Conversion:*
10 kg/cm2 ≈ *142 PSI*
1 kg/cm2 = 14.22 PSI, so 10 × 14.22 = *∼142 PSI*
That’s the pressure it’s designed to pop open at to relieve excess pressure.
Don’t exceed it — safety valves are set at the factory and shouldn’t be adjusted without testing.